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The Impact of Electronic Gaming Machine Jackpots
on Gambling Behaviour
Commissioned by
Gambling Research Australia
Prepared by:
Assoc. Prof. Matthew J. Rockloff
Prof. Nerilee Hing
Dr. Phillip Donaldson
Dr. En Li
Dr. Matthew Browne
Ms. Erika Langham
Funded by the State and Territory Governments and the Australian
Government
Published on behalf of Gambling Research Australia
by the Office of Liquor, Gaming and Racing
Department of Justice, Melbourne, Victoria, Australia
JANUARY 2014
We gratefully acknowledge the advice from Sarah Hare of Schottler Consulting
concerning the conduct of the Shadowing Study described in Chapter 7
ACRONYMS
ABS Australian Bureau of Statistics
CPGI Canadian problem gambling index
EGM Electronic gaming Machine
GRA gambling research Australia
NLES Negative Life events Scale
PGSI Problem gambling Severity Index
SA South Australia
2
Contents
Chapter 1: Executive Summary.........................................................................................................15
1.1 Literature Review......................................................................................................................16
1.2 Experiments on Structural Features of EGM Jackpots.........................................................16
1.3 Progressive and Deterministic Jackpots ...............................................................................17
1.4 Veiled Jackpots.........................................................................................................................18
1.5 Socially Networked Jackpots ..................................................................................................19
1.6 Jackpot Expiry...........................................................................................................................19
1.7 Shadowing Jackpots ................................................................................................................20
1.8 Final Remarks............................................................................................................................22
Chapter 2: Literature Review.............................................................................................................23
2.1 Introduction...............................................................................................................................23
2.2 Definition and Structural Features of EGM Jackpots............................................................24
2.3 Types of EGM jackpots ............................................................................................................24
2.4 Lotteries and EGM Jackpots: Similarities and Differences..................................................26
2.5 Potential EGM Jackpot Wins ...................................................................................................28
2.6 Theories Applied to Jackpots..................................................................................................28
3
2.7 Rational, Biased and Irrational Views of EGM Jackpots.......................................................29
2.8 Rationality: Utility Theory and Expected Utility Theory........................................................30
2.9 Bias: Alternatives to Expected Utility Theory........................................................................31
2.10 Representativeness Heuristic.................................................................................................32
2.11 Availability Heuristic................................................................................................................33
2.12 Anchoring and Adjustment Heuristics ..................................................................................33
2.13 The S-Shaped Value Function................................................................................................34
2.14 Irrationality: Faulty Cognitions about EGM Jackpots..........................................................35
2.15 Gambler’s Fallacy ....................................................................................................................36
2.16 Entrapment...............................................................................................................................36
2.17 Optimism...................................................................................................................................37
2.18 Superstitious Beliefs ...............................................................................................................38
2.19 Illusion of Control ....................................................................................................................38
2.20 Near Miss..................................................................................................................................39
2.21 Roll Over Effects......................................................................................................................40
2.22 Theory of Demand for Gambles .............................................................................................40
2.23 Advertising ...............................................................................................................................41
2.24 Ignorance of probability..........................................................................................................42
4
2.25 Evidence on Wins Affecting Behaviour.................................................................................42
2.26 Anecdotal and Self-Report Evidence for Gambling Motivation from Jackpot Wins.........43
2.27 Counter Evidence for Gambling Motivation from Jackpot Wins ........................................44
2.28 Some Evidence for Gambling Motivation from Jackpot Wins ............................................45
2.29 Connection between Risky Behaviour and Harm.................................................................46
2.30 Gambling Intensity as a Measure of Harm ............................................................................47
2.31 Consumption as an Indicator of Harm...................................................................................47
2.32 Harm Associated with Rational, Biased and Irrational Views of EGM Jackpots...............48
2.33 Literature Summary.................................................................................................................49
2.34 References................................................................................................................................52
Chapter 3: Experiment 1 Progressive and Deterministic Jackpots...............................................57
3.1 Progressive versus Non-progressive Jackpots ....................................................................57
3.2 Deterministic versus Non-deterministic Jackpots................................................................58
3.3 Jackpot Size ..............................................................................................................................58
3.4 Purpose of the Experiment ......................................................................................................59
3.5 Methods .....................................................................................................................................59
3.5.1 Participants ................................................................................................................59
3.5.2 The Simulated EGM....................................................................................................60
5
3.6 Procedures ................................................................................................................................61
3.7 Design ........................................................................................................................................62
3.8 Results .......................................................................................................................................63
3.8.1 Data Analysis..............................................................................................................63
3.8.2 Average Bet Size........................................................................................................63
3.8.3 Speed of betting (Bets per Minute) ..........................................................................64
3.8.4 Persistence (Total Trials Played)..............................................................................65
3.8.5 Subjective Enjoyment................................................................................................65
3.8.6 Physiological Arousal (GSR/Skin Conductance)....................................................65
3.8.7 No-jackpot Condition.................................................................................................65
3.9 Discussion..................................................................................................................................66
3.10 Limitations................................................................................................................................67
3.11 Summary...................................................................................................................................68
3.12 References................................................................................................................................69
Chapter 4: Experiment 2 Veiled Jackpots ........................................................................................70
4.1 Hidden Jackpots .......................................................................................................................70
4.2 Mystery Jackpots......................................................................................................................71
4.3 Veiled Jackpots Experiment....................................................................................................71
6
4.4 Method .......................................................................................................................................72
4.4.1 Participants................................................................................................................72
4.5 Procedure ..................................................................................................................................72
4.5.1 The Simulated EGM ..................................................................................................72
4.6 Conditions .................................................................................................................................74
4.7 Results .......................................................................................................................................76
4.7.1 Data Analysis..............................................................................................................76
4.7.2 The Full Factorial Model............................................................................................76
4.7.3 The Control ANCOVA Model.....................................................................................77
4.7.4 Average Bet Size........................................................................................................77
4.7.5 Speed of Betting (Bets per Minute)..........................................................................79
4.7.6 Persistence (Total Trials Played)..............................................................................81
4.7.7 Self-rated Enjoyment.................................................................................................83
4.7.8 Physiological Arousal (GSR/Skin Conductance)....................................................84
4.8 Discussion..................................................................................................................................86
4.9 Limitations..................................................................................................................................87
4.10 Conclusion................................................................................................................................88
4.11 References...............................................................................................................................89
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Chapter 5: Experiment 3 Socially Networked Jackpots..................................................................90
5.1 Impact of Socially Networked Jackpots on Gambling Intensity and Player Enjoyment ..90
5.2 Socially Networked Jackpot Experiment................................................................................91
5.3 Method .......................................................................................................................................91
5.3.1 Participants...................................................................................................................91
5.4 Procedure ..................................................................................................................................92
5.4.1 The Simulated EGM ..................................................................................................92
5.5 Conditions .................................................................................................................................93
5.6 Results .......................................................................................................................................95
5.6.1 Data Analyses.............................................................................................................95
5.6.2 Average Bet Size........................................................................................................95
5.6.3 Speed of Betting.........................................................................................................97
5.6.4 Persistence (Total Trials Played)..............................................................................98
5.6.5 Last Bank....................................................................................................................99
5.6.6 Enjoyment.................................................................................................................101
5.6.7 Physiological Arousal (GSR)..................................................................................102
5.7 Discussion..............................................................................................................................103
5.8 Limitations..............................................................................................................................103
8
5.9 References................................................................................................................................105
Chapter 6: Experiment 4 Jackpot Expiry........................................................................................106
6.1 Jackpot Expiry Feature............................................................................................................106
6.2 Validation of Jackpot Expiry...................................................................................................107
6.3 Jackpot Expiry Experiment.....................................................................................................107
6.4 Methods ....................................................................................................................................107
6.4.1 Participants.................................................................................................................107
6.5 Procedure .................................................................................................................................108
6.5.1 The Simulated EGM ...................................................................................................108
6.6 Conditions ................................................................................................................................109
6.7 Results ......................................................................................................................................110
6.7.1 Data Analysis.............................................................................................................110
6.7.2 Average Bet Size.......................................................................................................111
6.7.3 Speed of Betting (Bets per Minute).........................................................................112
6.7.4 Total Trials Played ....................................................................................................114
6.7.5 Losses past 20th Trial ...............................................................................................115
6.7.6 Enjoyment..................................................................................................................117
6.7.7 Physiological Arousal (Skin Conductance) ..........................................................118
9
6.8 Discussion..............................................................................................................................120
6.9 Limitations..............................................................................................................................120
6.10 Conclusion..............................................................................................................................121
6.11 References..............................................................................................................................122
Chapter 7: Shadowing Jackpots .....................................................................................................123
7.1 Method .....................................................................................................................................123
7.1.1 Participants...............................................................................................................123
7.2 Procedure ................................................................................................................................124
7.3 Player-characteristics: pre-play survey and priming manipulation ..................................125
7.4 Shadowing: Live observation of play ...................................................................................125
7.5 Machine characteristics .........................................................................................................126
7.6 Play characteristics ................................................................................................................126
7.7 Results .....................................................................................................................................127
7.8 Total gambling time and EGM switching rate......................................................................128
7.9 Bivariate relationships between player and session characteristics................................130
7.10 The effect of PGSI score and priming on EGM selection ..................................................131
7.11 Effects of PGSI and Jackpots on Money Invested and Number of Rounds Played........134
7.12 Structural modelling of EGM session dynamics................................................................136
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7.13 Clustered observations over participant and EGM model.................................................139
7.14 Effects on money withdrawn at end of session..................................................................140
7.15 Discussion..............................................................................................................................142
7.16 References..............................................................................................................................146
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Contents - Tables
Table 2.1 The Fourfold Pattern of Risk in Prospect Theory .....................................................34
Table 4.1 Assignment of Subjects to Conditions .....................................................................75
Table 4.2 ANCOVA predicting Average Bet Size..................................................................... 78
Table 4.3 ANCOVA predicting Speed of Betting (Bets per Minute) .........................................80
Table 4.4 ANCOVA predicting Persistence (Trials Played) .....................................................82
Table 4.5 ANCOVA predicting Enjoyment (6 point Likert item) ...............................................84
Table 4.6 ANCOVA predicting Physiological Arousal (GSR/Skin Conductance) ....................85
Table 5.1 Assignment of Subjects to Conditions .....................................................................94
Table 5.2 ANCOVA predicting Average Bet Size..................................................................... 96
Table 5.3 ANCOVA predicting Speed of Betting ......................................................................98
Table 5.4 ANCOVA predicting Total Trials Played................................................................... 99
Table 5.5 ANCOVA predicting Last Bank...............................................................................100
Table 5.6 ANCOVA predicting Enjoyment..............................................................................101
Table 5.7 ANCOVA predicting Skin Conductance/GSR .......................................................102
Table 6.1 Assignment of Subjects to Conditions.................................................................... 110
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Table 6.2 ANCOVA predicting Average Bet Size................................................................... 112
Table 6.3 ANCOVA predicting Speed of Betting ....................................................................113
Table 6.4 ANCOVA predicting Total Trials Played.................................................................115
Table 6.5 ANCOVA predicting Total Trials Played.................................................................116
Table 6.6 ANCOVA predicting Skin Conductance Change....................................................118
Table 6.7 ANCOVA predicting Skin Conductance Change....................................................119
Table 7.1 Summary statistics of numeric player and session variables.................................128
Table 7.2 Regression of player characteristics on rate of play............................................... 129
Table 7.3 Bivariate correlations between EGM session play characteristics, age and
participant PGSI score............................................................................................131
Table 7.4 Relationship between participant characteristics and EGM selection....................133
Table 7.5 Average maximum jackpot of EGM selected by participants by PGSI status and
priming manipulation...............................................................................................134
Table 7.6 Regressions of gambler and machine characteristics on funds invested...............135
Table 7.7 Logistic (1) and Tweedie Models predicting Money Out from Session Variables
and Demographics................................................................................................141
13
Contents - Figures
Figure 3.1 Illustration of Simulated EGM..................................................................................60
Figure 3.2 Average Bet Size by (non-)progressive characteristic, (non-)deterministic
characteristic, andjackpot size ................................................................................64
Figure 4.1 Simulated EGM depicting the jackpot amount and winning symbol combination....74
Figure 4.2 Betting Speed by Condition ....................................................................................81
Figure 4.3 Persistence (Total Trials Played) by Condition .......................................................83
Figure 4.4 Physiological Arousal (GSR).....................................................................................86
Figure 5.1 Simulated EGM depicting the jackpot amount .........................................................93
Figure 5.2 Average Bet Size by Jackpot Type ..........................................................................97
Figure 6.1 The Simulated EGM ...............................................................................................109
Figure 6.2 Speed of Betting by Message-Condition ................................................................114
Figure 6.3 Losses Past Trial 20 by Incentive and Message Type ...........................................117
Figure 7.1 Path model of game session variables ..................................................................138
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Chapter 1: Executive Summary
This report was commissioned by Gambling Research Australia (GRA) to examine the
impact of EGM jackpots on player behaviour. Specifically, the research was devised to
answer the question: “Do jackpots and linked jackpots increase the likelihood of risky
gambling behaviour and gambling related harm, and to what extent do jackpots enhance the
player experience?” A $250,000 project budget funded research activities from November
2011 to December 2013. This report documents those activities, including summaries of:
• Past literature related to the behavioural influences of EGM Jackpots
• 3 experiments examining the motivating influence of common structural features of
jackpots, including accumulation methods and payout mechanics
• 1 experiment examining ‘jackpot expiry’, which is a new proposed player protection
feature
• An observational study that explores the influence of Jackpots on EGM gambling in
real pubs and clubs in both Queensland and New South Wales
This research question was approached using two methodologies: 1) lab-based experiments
that simulated structural features of common types of jackpots, and 2) an in-venue
‘shadowing’ study whereby the researchers followed and recorded the play of volunteer
EGM gamblers. The experimental studies maintained a high degree of control and internal
validity in assessing the behavioural effects from various structural features of jackpots. The
‘shadowing study’ assessed the influence of jackpots in a natural setting (i.e., pubs and
clubs) where the influence of structural features was less tractable, but nevertheless allowed
for some important insights into the influence of jackpots on play. The strength of this dual
approach; experiment and in-venue observation; was found in the convergence of evidence
that indicates EGM jackpot have a demonstrable influence on intensification of player
behaviour.
15
1.1 Literature Review
This report includes a literature review on the behavioural impacts of EGM jackpots. Some of
the information in the review was first published in the Journal of Gambling Studies as a
strategy for early dissemination of results from the larger project.
As outlined in the review, prior to this report there has been little direct evidence on the
influence of EGM jackpots on behaviour, which suggests that the original data reported here
is timely. Nevertheless, there is a host of more general evidence on lotteries and other prize
draws (e.g., so-called “big wins”) that indicates that EGM jackpots should have an influence
on player behaviour.
First, the review recognises that jackpots have a primary effect through the promise of an
outsized win, instead of the actuality of winning. For non-regular gamblers, jackpot prizes are
exceedingly rare. Therefore, at least for most players, jackpots are likely to exert a
behavioural influence mainly through the mere possibility of winning rather than modifying
play after receiving a rare jackpot prize.
The review identifies a distinction between rational, biased and irrational motivations that
attract people to EGM jackpots. The evidence cited in the review suggests that EGM
jackpots should generate additional consumption on EGMs above machines that do not
have such lottery-like features. Rational motivations are likely to lead to consumer surplus
(i.e., a gain by paying less for a product than what consumers are willing to pay), whereas
biased and irrational motivations are likely to contribute to excessive and harmful
consumption. Moreover, there is evidence that excessive gambling consumption is strongly
associated with gambling-related harm.
1.2 Experiments on Structural Features of EGM Jackpots
There are structural characteristics of EGM jackpots that potentially impact on how players
perceive the value, excitement or enjoyment derived from a jackpot prize. Three experiments
16
were devised to investigate these common features of jackpots, and determine if the nature
of the presentation of jackpots affects play behaviour and enjoyment. A fourth experiment
investigated on original idea on Jackpot Expiry, which is a player-protection feature of a pre-
commitment system whereby jackpots would expire after a fixed amount of play.
1.3 Progressive and Deterministic Jackpots
Jackpots are financed from an accumulation of funds (losses) from regular play. In a
Progressive Jackpot, the prize amount grows incrementally with every new bet placed. In
contrast, a non-progressive jackpot has a fixed dollar prize. Deterministic Jackpots have a
payoff mechanism whereby the EGM will payoff at some fixed interval (# of bets) that is
determined in advance, but hidden from the player. These jackpots are guaranteed to payoff
at sometime within a fixed interval of play. In contrast, non-deterministic jackpots may payoff
at any time, as calculated at random with each bet.
Experiment 1 investigated the joint influence of Progressive and Deterministic jackpot
feature sets on player behaviour in a crossed-design. Using real money, players gambled on
a laptop-simulated EGM with real jackpot prizes of either $500 cash or 500 Instant Scratch
tickets for a $25,000 top prize. The results revealed that players placed the largest bets on
high jackpots EGMs ($25,000 ticket prize) that were represented to be deterministic and
non-progressive. These results were supportive of a hypothesized ‘goal distance effect’,
whereby players may have felt subjectively close to an inevitable payoff for a high-value
prize. Thus, this experiment shows that high-value deterministic jackpots may encourage
more intensive play.
Large jackpots ($25,000 top prize) that were non-deterministic and progressive also
promoted high bet sizes. This is a common configuration of jackpots in real venues, and
further suggests that some jackpot configurations do have an intensifying effect on player
behaviour, with betting sizes for this combination 18.4% higher than the average of other
jackpot configurations. The high bet sizes in this condition may be due to the rolled-over
17
effect noted in lottery betting, whereby players imagine that their large bets can be later
recouped through a big win.
Lastly, there was no evidence of differences in player enjoyment of the EGM experience
based on these jackpot configurations.
1.4 Veiled Jackpots
Another structural feature of some jackpots includes the ability to conceal aspects of the
jackpot from players. In a Hidden Jackpot, the exact dollar-value of the jackpot prize is
concealed from players. This may cause some extra inducement and/or enjoyment for
players due to the unknown – and therefore potentially unlimited – value of the top prize.
In a Mystery Jackpot the exact combination of symbols for the “winning state” of the machine
is concealed from players. This is often a natural consequence of a jackpot accumulation
system that sits outside of EGMs in a linked jackpot scheme, and uses the EGM only as a
triggering device. It would be procedurally complicated to have a fixed symbol combination
on each machine trigger the payout of the jackpot.
A crossed experimental design examined both ‘veiled’ aspects of EGM jackpots, Hidden and
Mystery, to determine their influence on player behaviour and enjoyment. The results
showed that suggestively large jackpot prizes (lottery tickets) where the dollar value of the
prize was hidden from players (i.e., not shown on the EGM as the potential $25,000 top
prize), but where the winning symbol combination was displayed (a non-mystery) contributed
to both the fastest gambling speeds (Bets per Minute) and greatest persistence while losing
(Total Trials Played). It is possible that Hidden Jackpots can suggest a very large prize, and
furthermore that a display of winning symbols can suggest that the prize is obtainable.
18
Thus, the present study suggests that suggestively large Hidden jackpots (a concealed
prize) can contribute to intense gambling, but there is no evidence that Mystery Jackpots (a
concealed winning combination) do the same. There was no evidence for differences in self-
rated enjoyment of the EGM for either type of concealment.
1.5 Socially Networked Jackpots
Linked Jackpots can potentially be won on several machines, but the trigger of a win on one
machine necessarily precludes a win on another. Linked jackpots can be shared only within
one venue (a local area) or shared across multiple venues (a wide area).
Linked jackpots (also termed Socially Networked Jackpots) may artificially increase the
perceived likelihood of winning a large prize, particularly as a very large prize can be pooled
across many contributing machines. Socially networked jackpots allow for higher jackpot
prizes with a smaller contributing investment per machine, and therefore are less taxing on
EGM intermittent win schedules.
The experiment used a fake video-conference paradigm to simulate groups of remote
participants (wide area), or alternatively a collection of confederate subjects to simulate a
venue-based linked-jackpot (local area). There were no significant differences in player
behaviour or enjoyment between the conditions. However, we purposefully did not attempt to
simulate other in-group/out-group effects that potentially could also influence player
behaviour and enjoyment. This is an area for future research.
1.6 Jackpot Expiry
Given the evidence for the motivating influence of EGM jackpots on intensifying player
behaviour (as outlined in more detail below), there is good reason to explore consumer-
19
protection features. Jackpot Expiry is a potential feature of a mandatory pre-commitment
system whereby the availability of jackpots expires after a fixed interval of play.
In the test condition, players were shown a “relevant” message stating that the promised
jackpot had expired and could no longer be won by the participant (after the 20th trial). In the
irrelevant message condition a similar pop-up message simply said to push the button to
continue. Lastly, a control condition had no pop-up message about the jackpot expiring. The
results showed that betting speeds (one indicator of gambling intensity) were significantly
slowed by the relevant ‘expiry’ message. Most importantly, all wagers past the 20th trial were
programmed as losses. Player receiving the ‘expiry’ message quit with significantly more
money remaining on the machine. Therefore, Jackpot Expiry is effective in limiting player
losses, as well as providing additional evidence on the motivating effects of jackpots on
player behaviour. Lastly, there was no evidence that Jackpot Expiry reduced self-rated
player enjoyment of the EGM experience.
1.7 Shadowing Jackpots
To enhance the external validity of our findings, another study was conducted in three
gambling venues (2 in QLD and 1 in NSW), whereby the researchers shadowed volunteer
players as they gambled in their local venue. Prior to play, approximately ½ of participants
were ‘primed’ to think about what aspirational purchases they might make with a jackpot win.
At-risk gamblers who were ‘primed’ to think about jackpot wins were more likely to select
large-jackpot oriented machines. These results suggest that large jackpots have a
preferential bias in attracting players with problems, as long as these players are thinking
about what the wins might buy them.
20
Moreover, at-risk gamblers responded to jackpot-oriented machines (with more and larger
prizes) by playing more rounds. There is evidence that at-risk gamblers both preferentially
select jackpot oriented machines and play more intensively on them.
More generally, jackpot-oriented machines were reliably associated with a greater spend on
the machines across all participants (problem and non-problem players). This finding
confirmed the intensifying effects of EGM jackpots on player behaviour. It is consistent with
some of the findings on common jackpot combinations explored in the experimental studies,
as well as theoretical consideration outlined in the literature review. Part of the higher spend,
however, may be a consequence of greater persistence on the jackpot-oriented machines.
Moreover, it was not possible in the dataset to distinguish between greater spend or
persistence as being a primary consequence of jackpot-oriented machines as the two are
functionally related. A higher spend allows greater persistence on the machines, and greater
persistence on average implies a greater spend.
The results also showed some notable observations about EGM gambling that are not
specific to jackpots. First, players with more gambling-related problems spent a longer total
time at the venue gambling, which is consistent with prior survey research. Second, players
with gambling problems played relatively fewer trials per EGM machine (bets placed). This
may be a consequence of higher average bet sizes that quickly expended available funds.
Lastly, the study explored the functional relationship between money-in on EGMs, number of
bets, money won and money out. There was surprisingly little direct relationship between
money put into a machine and money out. Funds withdrawn at the end of a session appear
to be primarily driven by the random and highly variable return schedule of the EGM.
Moreover, money-in during an EGM session was reliably related to wins. As a consequence,
a player experiencing wins was actually at greater risk of losing more money at cash-out.
This counter-intuitive finding can be understood in terms of the intensification of gambling
behaviour due to the experience of wins.
21
1.8 Final Remarks
This report provides some of the first direct evidence on the motivating influence of EGM
jackpots on player behaviour and enjoyment. While we found little evidence for large
differences in enjoyment based on the jackpot features of machines, this cannot be taken as
evidence that players do not value this feature of EGMs. Our literature review suggests that
people have rational, biased and irrational means to value jackpot EGMs over similar
machines without jackpots. Moreover, experimental and in-venue research demonstrates
that high-value jackpot machines intensify betting behaviour, and are differentially attractive
to at-risk players. The research suggests jackpots are an appropriate target for regulatory
attention. Lastly, we provided an experimental evaluation of a player-protection feature,
Jackpot Expiry, that maintains the consumer-surplus value of jackpots while minimising the
potential for jackpots to contribute to excessive gambling expenditure.
22
LiteratureReview
Chapter 2: Literature Review
Note: Please note that a version of this chapter has been published as: Rockloff, M. & Hing,
N. (2013, online first). The impact of jackpots on EGM gambling behavior: A review. Journal
of Gambling Studies. DOI: 10.1007/s10899-012-9336-7. The link to this paper is:
http://link.springer.com/content/pdf/10.1007%2Fs10899-012-9336-7.pdf The authors have
permission from Springer to re-use parts of this article in this chapter.
2.1 Introduction
Gambling Research Australia commissioned this current report in response to a call by the
Productivity Commission (2009) for research on the potential of EGM Jackpots to
exacerbate gambling problems. The primary research question to be addressed in this report
includes, ‘Do jackpots and linked jackpots increase the likelihood of risky gambling
behaviour and gambling related harm, and to what extent do jackpots enhance the player
experience?’
This chapter reviews literature on the influence of jackpots on gambling behaviour, focusing
on jackpots and so-called “big wins” on Electronic Gaming Machines (EGMs, including, fruit,
slot and VLT machines) (Kassinove & Schare, 2001). Evidence linking jackpots to risky
behaviours on EGMs (e.g., gambling persistence, bet size, speed of betting, etc.) and
relating these so-called “risky” behaviours to identifiable harms is also reviewed.
In structuring the chapter in this way, this review aims to provide an evidence base for
understanding features of jackpots that may be important in relation to problematic play. It
also aims to clarify what behaviours and features need to be measured in future studies to
inform evidence-based policy decisions in relation to EGM jackpots.
23
LiteratureReview
2.2 Definition and Structural Features of EGM Jackpots
While a jackpot has been defined as the largest prize possible on a gamble (Webster, 2006),
various EGM jackpot schemes offer more than one “top prize”, and the size of these top
prizes means that each is generally considered a jackpot win. Thus, jackpots are
distinguished from ordinary wins by their magnitude rather than by other structural features,
even if jackpots have concrete definitions in legislation and regulation. Nevertheless, these
legal definitions vary by jurisdiction and may include structural features, such as the means
by which a jackpot prize accumulates (cf., The State of Queensland, 2010).
Various types of jackpots exist, with this variation underpinned by their structural features
which, in turn, determine the jackpot prizes. These structural features may impact on how
people value prospective gambles or game attractiveness, but research evidence is unclear.
Common types of EGM jackpots with varying structural features include: progressive versus
non-progressive; deterministic versus non-deterministic; hidden jackpots; mystery jackpots;
linked versus standalone jackpots; and local-area versus wide-area jackpots (e.g., The State
of Queensland, 2010). These types of jackpots are described in Box 2.1. It is important to
note that EGM jackpots, both nationally and internationally, may have other exotic payoff
and accumulation mechanics that are not described here. Moreover, terms used to describe
these jackpot features are used somewhat inconsistently by the gambling industry.
2.3 Types of EGM jackpots
Progressive versus Non-progressive Jackpots
McPherson provides a definition of jackpots as “An accumulated amount that is contributed
to, and available within, the prize pool” (2007, p. 316). Ultimately, all jackpots are funded by
an accumulation of player expenditures (losses), but progressive (aka cumulative) jackpots
incrementally grow in value as players make additional bets. In contrast, non-progressive
jackpots are for a fixed prize amount - even though that amount is funded by an
accumulation of losses from other players.
24
LiteratureReview
Deterministic versus Non-deterministic Jackpots
Deterministic jackpots have a guaranteed payout after a fixed number of gambles (the
target), which is determined at random and concealed from the player’s view. As a result, the
likelihood of winning necessarily grows as players continue to bet, although the interval until
the next payoff is not known. It is difficult for the player to capitalize on this continuous
improvement in the likelihood of winning, however, as the interval until the next jackpot win
could be very long. As a possible exception, Hing (2007) reported on syndicates of players
that attempted - with some apparent success - to dominate play on EGMs that draw near to
an inevitable payoff. Non-deterministic jackpots, in contrast, have a constant probability of
winning. Potential awards are assessed at random with every bet. While the probability of
winning the jackpot is fixed in non-deterministic jackpots, this probability of winning may be
based on each bet placed or the cash value of each bet. If the chance of winning is based
on each bet placed then, perversely, a series of small bets has a greater likelihood of
winning a jackpot than one large bet of equal cash value.
Hidden Jackpots
In a hidden jackpot, the prize amount(s) is not shown to the player, although the existence of
a jackpot prize is advertised. This may cause some extra excitement and/or enjoyment for
players due to the unknown – and therefore potentially unlimited – value of the top prize.
Mystery Jackpots
In a mystery jackpot, the “winning state” of the machine (e.g., combination of symbols) is not
shown to the players. Mystery jackpots can be a natural consequence of jackpot systems
that are independent of the core operation of the stand-alone EGM. Jackpot systems may be
added to several different types of machines, even machines from different manufacturers,
and thus each EGM bet is essentially a lottery draw for the grand prize of the jackpot
system. In a non-combinative mystery jackpot any losing sequence of symbols on the EGM
is just as likely to win the jackpot prize as a winning sequence, because the jackpot system
is essentially independent from the machine and uses the EGM only as a triggering device.
In contrast, a combinative mystery jackpot has a winning sequence of symbols on the
machine, but this combination is not shown to players prior to winning the jackpot.
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Linked versus Stand-alone Jackpots
Linked jackpots draws can be won on several machines (often a bank of machines located in
close proximity) and the trigger of a jackpot win on one machine necessarily precludes a win
on another. Stand-alone jackpots, in contrast, are tied to one machine, where the prize can
only be claimed on that machine.
Local-area versus Wide-area Jackpots
Linked jackpots might be either shared only within the same venue (local area), or shared
across multiple venues (wide-area). Multiple venues that share a jackpot often belong to the
same organization, but jackpots can also be shared across organizations though a common
relationship with the EGM manufacturer or other contracting agency that administers the
jackpot scheme.
Source: Rockloff & Hing, 2013.
2.4 Lotteries and EGM Jackpots: Similarities and Differences
Most research relevant to understanding jackpots has been conducted in the context of
lotteries. Both lottery prizes and EGM jackpots offer the prospect of a large prize for a
comparatively small bet and, thus, share structural similarities. Because each EGM bet
purchases a virtual lottery ticket in the draw of the major jackpot prize, simple EGM jackpot
schemes can be considered as conceptually equivalent to lotteries. Thus, the more
developed knowledge base on lotteries can inform this consideration of EGM jackpots.
Nevertheless, exploring how lotteries and EGM jackpots differ despite their structural
similarity remains a useful line of inquiry. For example, EGM jackpots may differ markedly
from lottery prizes in their motivational influence on players, as discussed later.
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Due to the structural similarities between lotteries and EGM jackpots, Ariyabuddhiphongs’
(2011) review of research on the psychology underlying lottery play can inform an
understanding of EGM jackpots. EGMs with jackpot features are a composite product,
combining regular play that involves minor wins and losses with the potential to win a very
large prize of the magnitude associated with lotteries. Of all lottery products, instant scratch
tickets are most similar to EGM jackpots because of the potential to win both very small and
very large prizes, and because the win or loss result is provided immediately by both forms
of gambling. Thus, instant scratch tickets have been described as a “slot machine on paper”
(Ariyabuddhiphongs, 2011, p. 2; Griffiths & Wood, 2001). However, unlike lottery products,
EGMs combine regular play with a chance to win a jackpot through a continuous, repetitive
and electronic betting medium (Griffiths & Wood, 2001).
A major difference between EGMs and lottery/instant lottery products is that EGMs are
strongly associated with gambling problems, while few players report loss of control or
harms arising from purchasing lottery/instant lottery products (Productivity Commission,
1999). This difference suggests that the motivational influence of EGMs is different from that
for lottery play, despite their similarities in bet size relative to potential prizes. This
motivational influence might differ because, to have a chance at winning an EGM jackpot,
players must also engage in a fast paced game that provides small wins and losses in a
short timespan. Because EGM jackpots are usually inseparable from regular play, the
subjective experience of consuming jackpot EGMs is different from the subjective
experience of consuming lotteries and instant scratch tickets. The most notable differences
are in the fast pace of play, opportunity for continuous betting and repeated small wins and
losses. Further, EGM play and the excitement of winning are visible to others in a gaming
room, in contrast to lottery/instant lottery play which is typically done in private. Evidence
suggests that gambling intensity is influenced by social motivations (Rockloff & Dyer, 2007;
Rockloff & Greer, 2010a; Rockloff, Greer, & Evans, 2012; Rockloff, Greer, & Fay, 2010).
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EGM jackpots might influence player behaviour in two distinct ways – through offering
“potential” and “actual” large jackpot prizes. Because EGM jackpots are won by only a small
minority of players, their influence for most people is psychological; being based on the
possibility rather than actuality of winning. Second, the actual experience of a jackpot win,
while rare amongst players, can influence subsequent gambling behaviour. Indeed,
experiencing a big win (although not necessarily a jackpot) is often implicated as a
motivating factor in the gambling trajectories of problem players (Custer & Milt, 1985).
2.5 Potential EGM Jackpot Wins
Limited research has investigated how potential EGM jackpots influence gambling
behaviour, although some experimental and other research is discussed below. More
relevant and important information, however, can be derived from research into lotteries.
Additionally, people’s decision making under risk has long attracted the interest of
economists (Kahneman & Tversky, 1979), who have often considered gambling as a
prototypical example. Thus, both the economic literature and research specific to gambling
can help to explain demand for jackpot EGMs.
2.6 Theories Applied to Jackpots
Theoretical explanations for the demand for lotteries (Ariyabuddhiphongs, 2011) can be
extended to at least partially explain the purchase value of jackpot EGMs. As noted earlier,
EGMs might be viewed as a composite product combining regular play accompanied by
modest wins with a highly unlikely, but nonetheless potential, jackpot prize. EGMs with
jackpots usually have lower payouts during regular play than EGMs without jackpots,
because an additional proportion of the turnover of jackpot EGMs is used to fund the jackpot
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prizes. Thus, one might expect that EGMs with jackpots provide a comparatively less
attractive gambling experience during regular play. However, this expectation assumes that
players can detect the lower regular payouts on jackpot EGMs. This may not be the case,
given the large short run variability in EGM game outcomes. Instead, the lottery-like
component of the EGM, that is the potential jackpot prize, may increase the EGM’s
attractiveness despite the lower long run payouts during regular play. To understand the
demand for EGM jackpots, this “added value” of the potential big win must be assessed.
Both economic theory addressing decisions under risk and the gambling-specific literature
can assist in this assessment.
2.7 Rational, Biased and Irrational Views of EGM Jackpots
Theoretical explanations for the attraction of EGM jackpots are underpinned by three
common themes, with each theme based on varying assumptions. One theme, the rational
approach, assumes that gambling is an economic activity that people pursue for financial
gain and an entertainment experience. A second theme suggests that gamblers value EGM
jackpots on a rational basis, but misunderstand and incorrectly overvalue EGM jackpots due
to systematic biases. A third theme suggests that gamblers have an irrational basis for
valuing EGM jackpots, including emotional reactions and/or superstitious beliefs. Because
these reactions and beliefs do not reflect a thoughtful process, they go beyond simple biases
or divergences from rationality. Thus, rational, biased and irrational motivations can be
proposed to explain why people value EGM jackpots. These three types of motivations are
not, of course, mutually exclusive. However, little is known about which motivations most
often underpin the valuing of EGM jackpots and which personal or situational factors
contribute to rational, biased or irrational views of EGM jackpots.
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2.8 Rationality: Utility Theory and Expected Utility Theory
Economists use the term “utility” to describe the satisfaction or enjoyment derived from the
consumption of a good or service. Utility Theory attempts to quantify this satisfaction or
enjoyment, or the unique “utility” gained from any consumption experience. As a key
component of neoclassical economic theory, Utility Theory suggests that, while consumers
may not be able to assign an exact utility to a product or service, their preferences reflect a
well ordered ranking of available alternatives according to their perceived utility. However,
this logic assumes that consumers make purchase decisions in an entirely rational manner
by attempting to maximize the satisfaction they gain based on an invariant assessment of
the utility of the goods and services on offer (Smith, 2003). However, this assumption has
often been criticized (e.g., Sen, 1977) in recognition that most consumers appear to be much
more fickle and inconsistent than Utility Theory assumes (Thaler, 1985).
Utility Theory also assumes that consumers know the utility to be derived from each potential
purchase and its alternatives; however, in reality consumer purchases are not always, or
even often, for a known experience of utility. Thus, Expected Utility Theory (Bernoulli, 1738;
Von Neumann & Morgenstern, 1947) was developed to recognize that many choices provide
only an uncertain utility. Therefore, consumers must evaluate the utility of a potential
purchase based on the estimated probabilities of receiving various outcomes from that good
or service.
Applying Expected Utility Theory to gambling, consumers must weigh their decisions by their
estimated probabilities of winning when faced with gambling opportunities. Thus, if
consumers are assured of winning they would always choose to gamble, and if they were
assured of losing - at least according to Expected Utility Theory - they would never choose to
gamble. If commercial gambling is assessed in purely monetary terms, its utility will always
be negative (Turner & Horbay, 2004) to account for gambling operator profits that are
derived from player bets. However, gamblers are also purchasing the possibility of winning
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and an entertainment experience, which both add utility to what would otherwise be a losing
proposition. Thus, Expected Utility Theory can explain gambling purchase decisions without
the need to consider biased perceptions (Marfels, 2001).
2.9 Bias: Alternatives to Expected Utility Theory
Expected Utility Theory has several limitations that are discussed in detail elsewhere
(Camerer, 1995). Many experiments using real money (Kahneman & Tversky, 1979), as well
as real world examples (List, 2005) have been shown to violate Expected Utility Theory.
Alternatives to Expected Utility Theory have been proposed, but consensus has not been
reached on an ideal replacement. Most relevant to this discussion is that these alternative
models recognize that people typically become more risk averse as their prospects of
winning improve, and conversely become more risk seeking as their prospects of winning
become more remote. Because EGM jackpots are a remote possibility, a common
assumption is that people will positively overweight (or bias) the remote possibility of a win in
their judgments of value.
Prospect Theory is one example of such an alternative model (Kahneman & Tversky, 1979;
1981; 1992). Prospect Theory is a psychological theory that attempts to explain some of the
departures from rationality observed in real world examples that violate expectations from
the standard economic model. Using a consistent approach to Expected Utility Theory,
Prospect Theory (Kahneman & Tversky, 1979) focuses on the probability weighted
outcomes from alternative consumption decisions. However, the value function in Prospect
Theory is more complex. The theory proposes that instead of evaluating products and
services according to a fixed value (utility) for consumption, people evaluate the “prospect”
of a consumption decision based on heuristics (or rules of thumb) that can depart from
rationality. Indeed, the original formulation of Prospect Theory referred to the “prospect” of
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winning a lottery, as one of the simplest examples of a consumption decision. Evaluating a
prospective lottery is comparatively simple, because the value of a cash prize is not
subjective and the probability of winning is (or can be) known.
According to Prospect Theory (Kahneman & Tversky, 1979) and later Cumulative Prospect
Theory (Tversky & Kahneman, 1992), people base a decision on whether to make a lottery
purchase or likewise gamble on an EGM by choosing a “reference point” that functions as a
demarcation line to evaluate whether a potential decision outcome is a gain or loss.
Evaluating gambles in the context of a ‘loss frame’ that encourages risk taking may be
particularly applicable to problem gamblers. The reference point is chosen based on a
heuristic, several of which are described in past research by Tversky and Kahneman (1974).
Several of the heuristics proposed by Tversky and Kahneman (1974) are relevant to
considering how jackpots may influence EGM gambling.
2.10 Representativeness Heuristic
People tend to judge the probabilities of a win based on similarities to a perceived parent
population (Tversky & Kahneman, 1974). Thus, for example, a player who observes that one
particular club or casino paid a jackpot may perceive a better likelihood of winning a jackpot
at that venue than at other venues. When a newsagent has sold a winning lottery ticket, it
sometimes advertises this fact, presumably in an attempt to strengthen this heuristic
amongst potential lottery ticket purchasers. Similarly, a jackpot win on one particular EGM or
type of EGM can create a positive reference point for that EGM or EGM type that exceeds
the objective probabilities of winning.
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2.11 Availability Heuristic
One common way by which people evaluate probabilities, or prospects, is by the ease with
which they can recall similar examples of outcomes (Kahneman & Tversky, 1979).
Therefore, an EGM gambler may recall a person winning a jackpot at a local venue or
nearby, and thereby incorrectly overestimate their personal probability of winning a similar
jackpot prize. The availability heuristic describes on the chronic accessibility in memory for
the features of winning states, rather than subjective interpretations of representativeness of
winning states to a parent population.
2.12 Anchoring and Adjustment Heuristics
Individuals will often anchor or fixate on an initial value when ordering preferences, even if
this has no rational basis. People may subsequently alter their original estimates from this
anchor value to account for more information (adjustment), but then neglect to completely
break free from the initial flawed estimate (Kahneman & Tversky, 1979). Thus, advertising
slogans such as “you have to be in it to win it” and “wouldn’t it be nice” may not be
completely trusted, but can nonetheless underpin the basis for an anchor by generating the
impression that it is at least possible to win. People may subsequently revise downward their
estimate of their own likelihood of winning the jackpot, but nevertheless do not correctly
revise it to “virtually impossible” - as would be warranted by a more objective evaluation.
The above heuristics should not be considered exhaustive of all possible ways by which
people choose a reference point. Indeed, other heuristics may exist that have not yet been
identified. Nevertheless, these three heuristics clearly could influence people’s perceptions
of the probability of winning EGM jackpots.
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2.13 The S-Shaped Value Function
After selecting a reference point against which a prospective gamble might be considered
either a gain or loss, people must evaluate the gamble according to a value function.
Tversky and Kahneman (1979) explained that a sigmoid (S-shaped) value function results in
a fourfold pattern of risk orientation in decision making. This fourfold pattern (Table 2.1)
aligns with many empirical observations (Thaler, Tversky, Kahneman, & Schwartz, 1997).
Table 2.1 The Fourfold Pattern of Risk in Prospect Theory
Gains Losses
Low probability Risk seeking Risk averse
High probability Risk averse Risk seeking
The fourfold configuration of risk suggests that individuals do not make purely rational
judgments among alternative choices (or gambles) as posited by Expected Utility Theory
(Von Neumann & Morgenstern, 1947), but instead weight these valuations according to
whether they perceive them as high or low probability outcomes. So, while a person who is
motivated to play EGMs because of the jackpot feature perceives the “gain” of the jackpot as
a “low probability” event, the valuation function indicates that people are risk-seeking with
respect to this decision (see Table 2.1). That is, the EGM player perceives the potential of a
large jackpot prize as a “possibility”, when instead it should more accurately be perceived as
a “near impossibility”. Interestingly, the fourfold pattern of risk indicates that small but more
frequent jackpots should be less prone to this distortion than large but less frequent jackpots.
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Therefore, Prospect Theory predicts that small (but higher probability) jackpots should be
less motivating to EGM players than large (but lower probability) jackpots.
The gambling literature confirms the motivating influence of large prizes (Cook & Clotfelter,
1993). Per capita lotto sales strongly increase as the population base increases and
consequently jackpots grow, demonstrating the predicted motivating influence of large, low
probability prizes. Cook and Clotfelter (1993) utilize the availability heuristic described above
to explain how people may overestimate the value of a lottery, thereby demonstrating a
biased evaluation.
2.14 Irrationality: Faulty Cognitions about EGM Jackpots
Some effects that can influence the attractiveness of EGMs entail more than simple biased
judgments, but instead indicate irrational thinking (Rogers, 1998). Applying many of the
irrational cognitions reviewed by Rogers (1998) could assist in understanding the motivating
influence of EGM jackpots on gambling behaviour. As discussed below, many of these
irrational cognitions appear more prevalent amongst problem gamblers as compared to non-
problem gamblers. This introduces the possibility that jackpots influence the EGM gambling
behaviour of problem players differently than they do for non-problem players. Anecdotally
jackpots have also been implicated in the development of gambling problems (Custer & Milt,
1985), suggesting that some people may be more vulnerable to the influence of a possible
jackpot win on their future gambling behaviour. Nevertheless, more empirical evidence is
needed.
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2.15 Gambler’s Fallacy
People tend to see chance events as somewhat evenly distributed across time, and so
expect that deviations from an expected sequence will correct themselves by making
recently infrequent outcomes more frequent in the future. These beliefs give rise to the
gambler’s fallacy. A common example of this fallacy is to believe that a long dry spell on one
particular EGM makes that machine “due” to payout sooner than other machines. People
can also apply the gambler’s fallacy to fixed-probability (non-deterministic) EGM jackpots.
For instance, a jackpot that has not paid out recently may be considered “due” to payout
soon, and therefore encourage more EGM play to capitalize on the perceived improvement
in odds. Thus, linked jackpots may exacerbate gamblers’ tendency to chase losses, and may
give rise to false expectations of success based upon a belief in the gambler’s fallacy
(Delfabbro, 2012). The gambler’s fallacy has been observed amongst lottery players
(Clotfelter & Cook, 1991, 1993; Suetens & Tyran, 2012; Terrell, 1994), roulette players
(Croson & Sundali, 2005) and EGM players (Walker, 1992a) and appears to be more
common amongst problem than non-problem EGM players (Joukhador, MacCallum, &
Blaszczynski, 2003; Turner, Zangeneh & Littman-Sharp, 2006).
2.16 Entrapment
When gamblers take personal responsibility for losing outcomes, their commitment to
gambling may escalate and they may continue to invest in their gambling to justify their sunk
investment in time and money (Brockner, Rubin, Lang, 1981). More generally, researchers
have long recognized that individuals fail to acknowledge that sunk costs are irrelevant to
their current decisions, and often inappropriately adhere to losing courses of action (Knox &
Inkster, 1968). Entrapment may be relevant to how EGM jackpots influence gambling
behaviour, because problematic players can continue to justify their gambling in the face of
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mounting losses by rationalizing that a jackpot prize would bring them back past even
money.
In support, Hare (2010) found that problem gamblers preferred to sit at machines with the
best jackpots or features compared to players with less severe or no gambling problems.
Additionally, one of the top triggers for players who exceeded their pre-commitment
decisions on EGMs was the availability of large linked jackpots. Further, compared to other
players, both moderate risk gamblers and problem gamblers more often played linked
jackpot machines and EGMs with higher jackpot prizes. Lastly, prior to playing, problem
gamblers were also more likely to think about what jackpots were available at the venue.
Similarly, Hing and Haw (2010) found a positive association between prioritizing the
availability of linked jackpots and problem gambling severity when choosing where to
gamble amongst people in treatment for gambling problems (N = 186). These findings are at
least consistent with problem players becoming entrapped by losses which they hope to
recuperate through a large jackpot win.
2.17 Optimism
People generally expect more positive outcomes for themselves than for others, but naturally
in aggregate these expectations cannot hold true. Similar to belief in good luck (Darke &
Freedman, 1997), which imagines luck as a personal attribute possessed by some people,
optimism bias is a descriptive explanation for people’s belief that they are likely to win a
jackpot prize when objective consideration of the odds would show such an outcome to be
virtually impossible. Optimism may increase the appeal of EGMs, particularly if individuals
consider that their odds of winning a jackpot are better than those of other players, and thus
they irrationally overvalue this feature of the machines.
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Hing and Breen (2005) found that some venue staff reported that jackpots – and particularly
wide-area linked jackpots – enticed them to gamble. Hing (2008) later found a statistical
association between problem gambling severity amongst gaming venue staff and being
tempted by the big jackpots on offer that they see at work. Although many gaming venues
prohibit staff from gambling at their workplace, the availability of wide-area jackpots
(encompassing other venues) as well as the experience of witnessing others win jackpots
may lead to unrealistic optimism for these employees and thus boost their motivation to
gamble.
2.18 Superstitious Beliefs
Some gamblers hold superstitious beliefs that logically unrelated events or objects can
influence the probability of wins (Chan & Ohtsuka, 2009; King, 1990; Joukhador,
Blaszczynski, & Maccallum, 2004, Toneatto, 1999). Although likely of only minor relevance
to EGM jackpots, superstitious beliefs that improve the perceived likelihood of winning the
jackpot prize (such as a lucky day or advertising symbol) may increase the attractiveness of
EGM play. Further, there is some preliminary evidence that problem EGM gamblers endorse
more superstitious beliefs than non-problem EGM gamblers and that such beliefs are
correlated with gambling intensity (Joukhador, Blaszczynski & MacCallum, 2004).
2.19 Illusion of Control
Illusion of control (Langer, 1975) is a phenomenon where players believe they can exercise
some control over randomly determined events. Although probably only a minor contributor
to the influence of EGM jackpots on gambling, players may believe they can exert some
control over the award of jackpot prizes by playing in venues or on EGMs that have won
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before. Further, experimental studies (Coventry & Norman, 1998; Ladouceur & Mayrand,
1984; Langer & Roth, 1975) have found that participants experiencing early big wins
attribute their results more to skill and personal control than participants not experiencing
early big wins. Jackpots, if won, may therefore potentially foster an illusion of control.
Additionally, Joukhador, MacCallum, & Blaszczynski (2003) found that illusion of control was
stronger amongst problem gamblers compared to non-problem gamblers.
2.20 Near Miss
The near miss is a motivating factor in gambling where a player perceives that they just
missed out on a winning event (Reid, 1986). Most commonly, a near miss on EGMs is when
a series of reels almost align in a winning combination, but fall short by just one errant
symbol. Near misses may also be relevant to EGM play if, for example, a player observes
that someone else wins a jackpot on a day when they did not gamble or wins a jackpot on a
machine they have just stopped playing. Experiencing a near miss can intensify commitment
to gambling, as the player perceives that increased commitment could convert a near win
into an actual win in the future. Thus, for instance, the gambler who did not play on the
winning day for a jackpot may commit to play on more days (or all days) to avoid falling short
again. Similarly, the player who witnessed someone else winning a jackpot on a machine
they had just ceased playing may commit to playing for longer sessions in the future. It is
also likely that this commitment is enhanced where the near miss pertains to a large jackpot
rather than to a smaller EGM prize.
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2.21 Roll Over Effects
Progressive EGM jackpots may have an extra motivating effect, given that that rolled over
lotteries tend to attract greater sales than original lotteries (Rogers, 1998). Progressive EGM
jackpots can be considered a type of lottery that is continually rolled over until won. For
deterministic jackpots, the odds of winning increase as the jackpot nears the trigger. For
non-deterministic jackpots, the lack of winning outcomes over time may instead make a
payout only appear due (in accord with the gambler’s fallacy). Moreover, roll-overs simply
increase the prize pool of EGMs over time, and therefore should directly contribute to
demand as prize amounts become large. Delfabbro (2012) raises several concerns about
progressive EGM jackpots. They can encourage gamblers to bet more per spin to increase
the accumulation amount; they provide a very strong justification for chasing and continued
gambling; and they may reinforce the view that persistence at gambling increases the
likelihood of winning the jackpot and so undermine responsible gambling messages
(Delfabbro, 2012). This view is accurate in the case of deterministic jackpots.
2.22 Theory of Demand for Gambles
Nyman, Welte and Dowd (2008) explain a Theory of Demand for Gambles that usefully
highlights another motivating feature of gambling. Beyond the anticipated monetary gain
from engaging in gambling, Nyman et al. suggest that people also perceive value in getting
“something for nothing”. That is, people perceive utility not only in winnings, but also in not
having to work for those winnings. This theory suggests that gambling should be particularly
attractive to individuals who are vulnerable in the labour market, because it provides them
with a perceived means of earning income without having to work for it. Likewise, the Theory
of Demand for Gambles predicts that economically vulnerable people will be particularly
attracted to EGM jackpot winnings, because these represent a substantial form of possible
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income that they do not have to work to obtain. This demand is irrational, however,
considering the poor likelihood of winning.
2.23 Advertising
While many jurisdictions place limits on EGM jackpot advertising (e.g., The State of
Queensland, 2010), even straightforward signage may have an effect in promoting EGMs as
a lottery vehicle, and remind potential players that large or life-changing prizes can be won
from gambling on EGMs when this would not the case without the presence of jackpots
(Delfabbro, 2012). Thus, people can be drawn to EGMs by prominent advertisement of the
top prize (the jackpot), even though other subsequent factors, such as intermittent wins,
keep them playing. Policies to restrict gambling promotional activities are based on the belief
that these activities may induce gambling in vulnerable groups, such as problem gamblers
and minors, or may serve to counteract advertising that promotes responsible or low-risk
gambling (Williams, West & Simpson, 2007). There is some support for these assertions. For
example, in one study almost half (46%) of a sample of pathological gamblers reported that
advertising triggered them to gamble (Grant & Kim, 2001). The second most common trigger
was “boredom/free time” (24%), and the third was “thoughts of winning” (19%). Thus,
promoting the size of a jackpot appears to provide two of these triggers – an advertising
trigger and a winning trigger. Other empirical studies (Binde, 2009; Derevensky, Sklar,
Gupta & Messerlian, 2010; Korn, 2005) have also found that gambling advertising appears
to trigger gambling amongst problem gamblers. Thus, exposure to jackpot promotions may
encourage problem gamblers to gamble more and it may also hinder their recovery attempts
(Binde, 2009).
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2.24 Ignorance of probability
Prospect Theory (Kahneman and Tversky, 1979), outlined above, provides one logical
account for how people distort probabilistic reasoning; however, a simpler proposition is that
people are ignorant of the true probabilities of winning a jackpot prize (Toneatto, 1999). Even
clearly presented objective odds may not impact meaningfully on a person’s subjective
judgment of the likelihood of winning. Thus, for example, a 1 in 14 million chance of winning
may not have as much impact as “if you gambled every day from birth and lived to be 100, it
would take you 383 lifetimes to win the jackpot.” (Ariyabuddhiphongs, 2011). It is likely that
people focus on the prize amount, rather than the probability of winning – as the probabilities
are far outside of commonplace likelihoods, gamblers appear to have difficulty incorporating
this information into decision making (Griffiths & Wood, 2001). This disregard of probability is
more aligned with what we have designated as an ‘irrational’ means of valuing EGM
jackpots. Whereas Prospect Theory (1979) suggests a biased view of EGM jackpots where
the low probability of winning is over weighted, ignorance of probabilities provides no rational
means for evaluating why an individual might want to take part in the gamble. In fact, many
of the irrational motivations discussed above are simply means by which people make
ignorant estimates of the probabilities of winning.
2.25 Evidence on Wins Affecting Behaviour
Most of the evidence discussed so far focuses on how the prospect of winning an EGM
jackpot may motivate gambling involvement. This focus is most important, since very few
gamblers – even regular gamblers – win large jackpots. Nevertheless, smaller jackpot
amounts may be within the aspirational reach of regular gamblers. Thus, it is also helpful to
understand whether a jackpot, once won, further stimulates EGM gambling involvement.
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2.26 Anecdotal and Self-Report Evidence for Gambling Motivation from Jackpot Wins
A frequent observation from clinical work and empirical studies is that many problem
gamblers experience a “big win” early in their gambling careers (Custer & Milt, 1985;
Greene, 1982; Livingstone & Woolley, 2008; Turner, Zangeneh & Littman-Sharp, 2006).
Gambling prevalence studies have also found that problems gamblers are likely to report
early big wins. For example, the Queensland Household Gambling Survey 2006-07
(Queensland Government, 2008) found that 68% of problem gamblers remembered a big
win when they first started gambling, compared to 51% of moderate risk gamblers and 42%
of low risk gamblers. In a psychological study with a battery of instruments administered to
social gamblers, sub-clinical problem gamblers and pathological gamblers, Turner,
Zangeneh and Littman-Sharp (2006) found that most gamblers reported wanting to gamble
more after a big win, although this varied between 73% of pathological gamblers and 21% of
non-problem gamblers. Further, nearly one-third of the sub-clinical and pathological
gamblers reported experiencing a big win just before gambling became a problem for them.
An early big win is subjectively felt to be a motivating factor in an individual’s continuing
gambling involvement (Custer & Milt, 1985). In particular, an early big win may create the
impression that reasonably large wins are fairly common, and thus gambling could represent
a net economic gain over time. Consistent with Walker’s Cognitive Theory of Gambling
Involvement (1992b), an early big win might also foster an individual’s belief in their own
ability to succeed at gambling and thus encourage persistence. Further, a big win, if used to
continue EGM gambling, leads to increased gambling involvement due to the numerous
extra spins made possible by the win. Blaszczynski and Nower’s (2002) Pathways Model
would predict that this strengthened behavioural conditioning may increase the likelihood of
later development of gambling problems. Thus, both big wins per se and the associated
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behavioural conditioning when big wins are recycled, may be associated with later gambling
problems (Harrigan & Dixon, 2010). Therefore, anecdotally, winning jackpots seems to have
the potential to exacerbate, or even cause, gambling problems (Custer & Milt, 1985).
2.27 Counter Evidence for Gambling Motivation from Jackpot Wins
Weatherly, Sauter et al. (2004) conducted a simulated EGM experiment with subjects who
were not experienced gamblers and with real money outcomes. In a between-subjects
design, these researchers included both small and large wins that were triggered at different
times during play. A control group had no wins. Participants who experienced a big win on
the 1st play stopped gambling earlier than other participants who experienced the same win
on the 5th play. Although the results appear consistent with behavioural theories related to
gambling (as extinction is delayed along with the delayed win), the researchers also stated
that the result appeared to question the “big win” as a motivating factor in continuation of
behaviour. In another experiment, Pisaniello (2003) also failed to find notable effects from
so-called “jackpot” wins on motivating persistence at gambling. Naturally, the big wins in
these experiments were necessarily much smaller than typical jackpot payouts, and thus
may not be entirely instructive in understanding how behaviour is influenced by winning
larger amounts. These studies are also not able to clarify whether big wins lead to
persistence across gambling sessions, that is, more frequent and/or longer subsequent
gambling sessions.
Lottery winners may be instructive in understanding the effects of large EGM wins on
subsequent gambling. A survey of 1986 Ohio millionaire lottery winners (Kaplan, 1988)
found that these prize winners spent relatively little money on tickets, did not appreciably
increase their expenditures on tickets, and rarely participated in other forms of gambling
either before or after they won. These results, of course, may simply reflect differences in the
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characteristics of people who typically play lotteries as opposed to EGM gambling; with EGM
gamblers more likely to participate in several forms of gambling and to have greater
gambling involvement overall (Holtgraves, 2009). Nevertheless, the findings of this lottery
study contradict the stereotype of the gambler who fritters away gambling winnings on
additional gambling products (Business Pundit, 2009). Moreover, research shows that lottery
winners are often better off after winning (Kaplan, 1987, 1988); and these gains in life
satisfaction are relatively lasting – extending up to three years.
Despite the structural similarity to EGM jackpots, lotteries are unlikely have the same
psychological appeal. Jackpots on EGMs are inseparable from the fast-paced repetitive
electronic betting medium used to purchase the chance at winning. Most importantly,
realized EGM jackpot wins may temporarily justify the large investment in play, whereas
monetary investment in lotteries is often so small as to be inconsequential.
2.28 Some Evidence for Gambling Motivation from Jackpot Wins
Young et al. (2008) conducted an EGM experiment in which participants experienced either
a large win or a series of small wins, and could continue gambling thereafter for as long as
they wished. All subsequent trials were programmed as losses. A single item measured
subjects’ desire to continue gambling. The results indicated that high-risk gamblers who
experienced a big win were more motivated to continue with their gambling than other
participants. This experiment therefore provided at least some evidence that winning
modestly large amounts stimulates the desire to continue gambling amongst at-risk players.
This finding does not necessarily imply, however, that these same players would return to
gamble on another occasion if they left a venue with a large win. Furthermore, like all EGM
experiments, the amounts won were relatively modest and not comparable to the jackpot
amounts typical of EGMs in real venues. Thus, the results must be interpreted with caution.
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Finally, Wilkes, Gonsalvez and Blaszczynski (2010) provided evidence that big wins reliably
produce changes in electrodermal response that are associated with physiological arousal.
Moreover, Rockloff and Greer (2010b) and Rockloff, Signal and Dyer (2007) have further
shown that arousal during EGM play is associated with risky gambling behaviours; including
increases in gambling speed, bet size and persistence; particularly for players with pre-
existing gambling problems who interpret their arousal as a positive feeling state.
In summary, some evidence exists that modest wins within experimental paradigms increase
gambling excitement and desire to continue playing. Further, excitement has been
associated with traces of behaviour indicative of gambling intensity; including betting speed,
bet size and persistence. However, surveys with Ohio lottery winners did not provide
evidence of increased gambling involvement after large, million-dollar-plus wins. Thus, the
best current evidence is that the mere presence of EGM jackpots may provide motivational
effects on gamblers, whereas the damaging effects of actual jackpot wins are more
ambiguous. Importantly, the experience of winning lotteries is not directly comparable to
winning EGM jackpots, because play on EGMs is also connected with an electronic betting
medium encompassing rapid, continuous play and intermittent small wins.
2.29 Connection between Risky Behaviour and Harm
Because few EGM players will experience a large jackpot win, it is most important to
understand whether the mere presence (or promise) of outsized jackpots leads to risky
behaviours that are implicated in producing harm.
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2.30 Gambling Intensity as a Measure of Harm
Measures of gambling intensity, such as betting speed, bet size and persistence, are
functionally related to harm because these behaviours tend to increase gambling losses
during long term play. The Productivity Commission Report (1999) calculated that playing
style can have a dramatic impact on costs, whereby players could expect average losses of
anywhere between $1.20 and $1,200 per hour dependent on their betting choices. Some
evidence also exists that such intense play behaviours are symptomatic of problematic play.
Braverman and Shaffer (2010) analysed a sub-sample of client data from the Internet betting
service provider “bwin” of all people who opened an account in February 2005 (N = 21,996).
The sub-sample comprised 599 people who gambled more than three times with the service,
and subsequently closed their account for a stated cause within a one month to two year
timeframe. Seventy-three percent (73%) of the people in this sub-sample eventually closed
their account due to gambling-related problems. When compared to the other respondents,
the behaviours of this self-identified high-risk subgroup included: (i) frequent betting, (ii)
intensive betting, (iii) high variability across wager amount, and (iv) an increased bet size
during the first month of wagering (p. 1). These markers of gambling intensity, therefore, are
also manifestly associated with self-identified problems from gambling.
2.31 Consumption as an Indicator of Harm
Other evidence points to excessive consumption of gambling products as an indicator of the
harms associated with problem gambling. Rockloff (2011) developed a Consumption Screen
for Problem Gambling (CSPG) that reliably predicts the existence of gambling problems
based on three questions regarding the frequency, amount and duration of gambling. This
research demonstrated that excessive consumption of gambling is strongly associated with
gambling problems. A cut-off score of 4+ on the scale accurately identified all 14 problem
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LiteratureReview
gamblers in sample of 1,396 people (100% sensitivity). In contrast, 7.3% of non-problem
gamblers scored at the 4+ level (specificity = 92.7%). Lastly, a more narrow 3% of gamblers
without any self-reported gambling problems scored over 4+ on the scale. Although the
scale showed a high number of false positives, high levels of consumption nonetheless
proved to be strongly associated with gambling problems.
In Canada, a survey (N = 19,012) conducted by Currie et al. (2006) found that the risk for
gambling problems increases with gambling frequency and expenditure. Receiver operating
characteristics analysis showed a cut-off for low risk participation in gambling to include: 1)
gambling no more than two to three times per month, 2) spending no more than CAN$501-
1000 a year (in net losses), and 3) spending no more than 1% of gross family income on
gambling. Further, Currie et al. (2008) replicated these findings in three independently
collected Canadian gambling surveys, compiling further evidence that validated these cut-off
values for harmful levels of gambling. Currie et al. (2006) and Currie et al. (2008) thus
provide additional evidence to suggest than any feature that increases gambling
consumption increases the risk of gambling-related harm. Therefore, EGM jackpots logically
at least have the potential to increase gambling consumption to harmful levels.
2.32 Harm Associated with Rational, Biased and Irrational Views of EGM Jackpots
Understanding whether gambling consumption is excessive, and therefore is likely to result
in harm, must take some consideration of how people value EGM jackpots. If people value
EGM jackpots on a purely rational basis, including the expected value of the prizes and the
entertainment value of imagining a jackpot win, then consumer surplus is created. In
contrast, bias in valuing the EGM jackpots may cause some people to overvalue EGM
jackpots and therefore overinvest their time and money in gambling on EGMs. There may be
avenues to correct these biases, however, through consumer education or structural reforms
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LiteratureReview
to maintain a more rational commitment to gambling. Lastly, some people may value EGM
jackpots on an entirely irrational basis, and the only avenue to reducing consumption below
harmful levels is to counteract these irrational means of valuing EGM jackpots.
An important part of the future research agenda is to evaluate which of the available
explanations for EGM jackpots (rational, biased and irrational) predominate, and what
explanations are more valid for whom – such as those at-risk of or already experiencing
gambling-related problems. As reviewed in this chapter, there is evidence that problem
gamblers are more likely than non-problem gamblers to hold a range of irrational beliefs
about gambling, but whether and how gamblers apply these irrational beliefs specifically to
EGM jackpots is unclear. Efforts needed to correct any biases or irrational motivations need
to be targeted appropriately.
2.33 Literature Summary
This literature review has provided an overview of research to date that contributes to an
understanding of the motivating influence of EGM jackpots on gambling behaviour. Specific
evidence about EGM jackpots is scant, but research and theorizing yields explanations for
motivation that can be broadly characterized as rational, biased and irrational. In particular,
theoretical perspectives including the rational approach of Expected Utility Theory (Von
Neumann & Morgenstern, 1947), various alternatives to Expected Utility Theory that assume
some bias (Kahneman & Tversky, 1979), and other more strictly irrational motivations
(Rogers, 1998), generate expectations that EGM jackpots should motivate additional
consumption on EGMs above those EGMs that do not have such lottery-like features.
Experimental evidence implies that modest wins may stimulate greater excitement and
desire to continue gambling, although this effect may be specific to problem gamblers and is
bound within a gambling session. Conversely, little direct evidence exists to suggest that
large wins generate increases in gambling involvement (Kaplan, 1987, 1988), but this may
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LiteratureReview
simply reflect that no direct evidence is yet available exploring EGM winnings as opposed to
lottery winnings. Lotteries and EGMs are likely to have dissimilar clientele and motivations
for gambling involvement.
The mere presence of jackpots in EGMs, rather than winning a jackpot, is likely to stimulate
gambling consumption. Further, excessive consumption is indicative of gambling problems,
and likewise, the harm associated with gambling problems (Currie et al., 2008; Currie et al.,
2006; Rockloff, 2011). Problem players demonstrate behaviours that contribute to higher
consumption rates, such as frequent betting, intense betting, and larger bet sizes
(Braverman & Shaffer, 2010).
An important distinction was drawn between rational, biased and irrational motivations
attracting people to EGM jackpots. Rational motivations alone imply few problems from EGM
jackpots, because gamblers participate in EGM play to gain monetary rewards and
entertainment that generate consumer surplus. Conversely, biased motivations that instead
lead individuals to overinvest time and money in gambling may contribute to the experience
of gambling problems. Nevertheless, there may be opportunities to correct the bias through
education or regulation, and thus more closely align EGM gambling with desirable levels of
personal expenditure. Probably most troubling, however, are irrational motivations that tend
to overvalue EGM jackpots. These motivations are not simply biased deviations from rational
reasons for participating in gambling, but instead represent forces that are distinct from the
enjoyment and reward of the activity. It is important that future research explains which of
these broad categories of motivations predominate, and how these motivations might differ
between individuals who are vulnerable to problems and others who gamble without
problems. Further, it is also important to understand how jackpots with different structural
features; such as progressive, deterministic, hidden, mystery, linked and wide-area jackpots;
might differentially appeal to rational, biased and irrational motivations to engage in EGM
gambling.
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More research is needed to fully understand the effects of EGM jackpots on gambling
behaviour (Livingstone, Woolley, Zazryn, Bakacs, & Shami, 2008, p. 154). Although there
are reasons to expect that large jackpot prizes will have an outsize influence on gambling
behaviour, these reasons need to be tested in the context of venue-based EGMs. Moreover,
little is known about how jackpots with different structural features that determine how
jackpots are awarded might similarly affect gambler behaviour. Because jackpots are an
integral and important feature of many – if not most – EGMs, it is critical to understand their
value to players, and likewise their potential influence on excessive consumption and by
extension problematic patterns of gambling. The original research in this report contributes
to this agenda.
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LiteratureReview
2.34 References
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Braverman, J., & Shaffer, H. J. (2010). How do gamblers start gambling: identifying
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Princeton: Princeton U. Press.
Cook, P. J., & Clotfelter, C. T. (1993). The Peculiar Scale Economies of Lotto. The American
Economic Review, 83(3), 634-643.
Currie, S. R., Hodgins, D., Wang, J., el-Guebaly, N., Wynne, H., & Miller, N. (2008).
Replication of Low-Risk Gambling Limits Using Canadian Provincial Gambling
Prevalence Data. Journal of Gambling Studies, 24(3), 321-335. doi: 10.1007/s10899-
008-9091-y
Currie, S. R., Hodgins, D. C., Wang, J., el-Guebaly, N., Wynne, H., & Chen, S. (2006). Risk
of harm among gamblers in the general population as a function of level of
participation in gambling activities. Addiction, 101(4), 570-580.
Custer, R. L., & Milt, H. (1985). When luck runs out: Help for compulsive gamblers. New
York: Facts on File Publications.
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Hing, N., & Breen, H. (2005). Gambling amongst gaming venue employees: counsellors’
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Holtgraves, T. (2009). Gambling, gambling activities, and problem gambling. Psychology of
Addictive Behaviors, 23(2), pp. 295-302. doi: 10.1037/a0014181
Joukhador, J., Blaszczynski, A., & Maccallum, F. (2004). Superstitious Beliefs in Gambling
Among Problem and Non-Problem Gamblers: Preliminary Data. Journal of Gambling
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Econometrica, 47(2), 263.
Kaplan, H. R. (1987). Lottery winners: The myth and reality. Journal of Gambling Studies,
3(3), 168-178. doi: 10.1007/bf01367438
Kaplan, H. R. (1988). Gambling among lottery winners: Before and after the big score.
Journal of Gambling Studies, 4(3), 171-182. doi: 10.1007/bf01018330
Kassinove, J. I., & Schare, M. L. (2001). Effects of the "near miss" and the "big win" on
persistence at slot machine gambling. Psychology of Addictive Behaviors, 15(2), 155-
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Knox, R. E., & Inkster, J. A. (1968). Postdecision dissonance at post time. Journal of
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Livingstone, C., Woolley, R., Zazryn, T., Bakacs, L., & Shami, R. (2008). The Relevance and
Role of Gaming Machine Games and Game Features on the Play of Problem
Gamblers: Independent Gambling Authority South Australia Prepared under the
auspices of Australian Institute for Primary Care (AIPC) La Trobe University.
Marfels, C. (2001). Is Gambling Rational? The Utility Aspect of Gambling. Gaming Law
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McPherson, J. (2007). Beating the odds: the complete dictionary of gambling and games of
chance Docklands, Vic. : GSP Books (Geoff Slattery Publishing).
Nyman, J. A., Welte, J. W., & Dowd, B. E. (2008). Something for nothing: A model of
gambling behavior. Journal of Socio-Economics, 37(6), 2492-2504. doi:
10.1016/j.socec.2008.02.011
Pisaniello, S. L. (2003). The Effect of Varying Jackpot Structure and. Illusory Control on
Psychological Entrapment in Gambling. (B of Jurisprudence), University of Adelaide
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ProgressiveandDeterministicJackpots
Chapter 3: Experiment 1 Progressive and Deterministic Jackpots
As documented in the literature review, there is little existing direct evidence on the influence
of the structural characteristics of EGM jackpots on gambling behaviour. To redress this
deficit, this present study examined two common structural features of EGM jackpots:
progressive versus non-progressive jackpots, and deterministic versus non-deterministic
jackpots. These features, as described below, were examined in an experimental design for
their potential effects on intensity of gambling and enjoyment, and for how jackpot size may
moderate such effects.
3.1 Progressive versus Non-progressive Jackpots
Progressive jackpots incrementally grow in value as players make additional bets.
Alternatively, non-progressive jackpots generate a fixed dollar payout irrespective of the
precise accumulation of losses from players. Two conflicting views can be postulated
regarding whether progressive or non-progressive jackpots should have more motivating
effects on players’ gambling intensity. On the one hand, evidence from lottery betting
(Rogers, 1998) suggests that progressive jackpots may lead to a “rolled over effect”,
whereby gamblers are encouraged to bet more as higher bets help increase the
accumulated amount of the jackpots. That is, each bet adds to the jackpot and that amount
may be seen as recoverable investment in the jackpot prize. On the other hand, EGM
players who consider hitting the jackpot as their goal may experience a “goal distance effect”
(Kivetz, Urminsky & Zheng, 2006). That is, progressive, rather than non-progressive
jackpots, may increase the perceived distance to the goal as the jackpot value grows after
each additional bet, and therefore decrease players’ motivation to pursue the jackpot reward.
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Moreover, progressive jackpots may make bettors more aware of their contributions to the
jackpot, which may be properly seen to be most likely to benefit someone else.
3.2 Deterministic versus Non-deterministic Jackpots
Deterministic jackpots have a guaranteed payout after a fixed number of bets, which is
determined at random but hidden from players. Non-deterministic jackpots, on the contrary,
have a potential payout assessed at random with every bet. Hence, a key difference
between them lies in the fact that the likelihood of winning a deterministic jackpots increases
as players continue to bet, whereas there is no guaranteed winning outcome over time for
non-deterministic jackpots (Rockloff & Hing, 2012). Therefore, deterministic jackpots may
lead to heightened betting motivation and reinforce persistence at EGM playing as players
have increasing odds of winning with every bet placed. Of course, gamblers likely have little
notion of how close they are to an inevitable payoff. Thus, deterministic jackpots are only
motivating if players perceive the payoff to be near, whereas they are less motivating than
non-deterministic jackpots if players feel that the payoff event is likely distant.
3.3 Jackpot Size
According to Kahneman and Tversky’s (1979) Prospect Theory, individuals tend to value
alternative choices (e.g., gambles) based on their perceived outcome probabilities. Small
jackpots payout more frequently than large jackpots, and regular players understand that
jackpot size is inversely related to the probability of winning. That is, small jackpots payout
more frequently than large jackpots. Prospect Theory predicts that EGM players should be
more motivated to place bets with small-probability large prizes, however, because people
are generally more risk-seeking with respect to low-probability events framed as a gains
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(Rockloff and Hing, 2012). The motivating influence of large, low probability prizes is also
supported by evidence from US lottery sales, where larger population states have higher
per-capita purchases of lottery tickets (Cook & Clotfelter, 1993).
3.4 Purpose of the Experiment
The present experiment was devised to investigate the interactive effects of (non-)
deterministic jackpots, (non-) progressive jackpots, and jackpot size on EGM gambling
behaviour in the forms of bet size, betting speed and betting persistence. In particular, we
sought evidence on the differential motivating effects of progressive versus non-progressive
feature of jackpots, in order to confirm evidence for the “rolled over effect” or the “goal
distance effect” effect on aspects of play and player enjoyment.
3.5 Methods
3.5.1 Participants
One hundred and twenty-three participants, including 51 male and 72 female subjects, aged
18 - 82 (M = 50.4, SD = 16.4) successfully completed the experiment following recruitment
from newspaper-flyer advertisements in Bundaberg, Queensland Australia. The cultural
backgrounds of participants included: 114 Australian (92.7%), 3 English (2.4%), 2 New
Zealand (1.6%), 2 German (1.6%), 1 South African (0.8%), and 1 other (0.8%). As calculated
from the post-experiment 9-item Problem Gambling Severity Index (PGSI, Ferris & Wynne,
2001), the problem-gambling status of participants included: 41 (33.3%) no identifiable
problems, 42 (34.2%) low-risk, 26 (21.1%) moderate-risk, 13 (10.6%) problem gamblers, and
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1 (0.8%) unclassified due to an incomplete questionnaire. Seventy-five percent (75%) of the
sample gambled on a casino style game at least once within the last 12 months.
3.5.2 The Simulated EGM
A simulated EGM was created by the study authors in Visual Basic (see Figure 3.1) and run
on a laptop computer. The machine had 3 reels and 3 pictured ‘fruits’ on each reel. Three
matching fruits defined winning outcomes across the win-line, and all winning bets paid-off at
10 times the amount bet. Players could bet amounts of 25, 50 or 100 cents on each trial (or
spin), with potential payoffs of $2.50, $5.00 and $10.00, respectively. Credits were presented
in cents, with an initial bankroll of 2,000 cents ($20) appearing at the start of play. Although
presented to the player as random, the machine was programmed with a fixed sequence of
5 wins (on spins 2, 6, 8, 13 and 20) and infinite losses thereafter. The theoretical maximum
payout was $61.25, which is calculated from the $20 initial bankroll, plus $50 in maximum
wins, and less $8.75 in minimum bets required. The EGM produced the typical noises
associated with play, including the musical sounds of spinning reels and winning bells.
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ProgressiveandDeterministicJackpots
Figure 3.1 Illustration of Simulated EGM
3.6 Procedures
Participants were given $20 upon arrival at their session as compensation for their time.
After completing a brief questionnaire including demographic questions and the Lie-Bet
Scale (Johnson et al., 1988), participants were asked whether they would like to wager their
$20 compensation on the EGM. The $20 cash compensation was retrieved from the
participants and loaded to the EGM for their subsequent play. Given the modest sample
size, stratified random assignment based on participants’ gender, age, and Lie-Bet score
was utilised to allocate participants to play the EGM in the different conditions (as described
below). Each participant had a finger sensor measuring skin conductance attached to the
middle finger of his or her non-dominant hand (Biograph Infinity System).
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3.7 Design
The experiment was based on a 2 (progressive vs. non-progressive) × 2 (deterministic vs.
non-deterministic) × 2 (small jackpot vs. large jackpot) factorial design with an additional no-
jackpot control condition. Participants in (non-) progressive and (non-) deterministic
conditions were informed of the mechanisms of the specific structural characteristics of their
EGM before they started playing both verbally and with an information-screen prior to play.
Further, participants in the small (versus large) jackpot conditions were told there was the
opportunity to win $500 as a cash jackpot (versus the opportunity to win instant scratch-it
tickets for a $25,000 jackpot) and shown a jar with $500 cash (versus 500 instant scratch-it
tickets). The language described each feature in functional terms without emotive words. As
an example, the deterministic, progressive, $25K jackpot condition players were told:
“The $25,000 prize amount will be shown on the top of the screen once you begin.
You’ll notice that the jackpot prize grows with every bet you make.
The ticket-jackpot will payout after a certain number of bets have been placed. The
number of bets that must be made before the jackpot is triggered has been determined
in advance and at random.”
The top jackpot prize, either $25,000 or $500, was additionally shown on the EGM as
illustrated in Figure 3.1. In the progressive condition, the displayed prize increments as a
function of player betting.
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3.8 Results
3.8.1 Data Analysis
The primary dependent variables of interest included the behavioural outcomes of average
bet size, betting speed (bets per minute), persistence (total trials played), and a one-item
self-reported measurement of subjective enjoyment of playing the EGM (a six-point Likert
scale). Each outcome was analysed with an ANCOVA model using (non-) progressive
feature, (non-) deterministic feature, and jackpot size as the primary predictive variables in a
crossed design. Gender, age, and Problem Gambling Severity Index (PGSI, Ferrris &
Wynne, 2001) were entered as covariates, as none of these variables proved useful in
producing significant interactions.
3.8.2 Average Bet Size
The first ANCOVA model showed a significant three-way interaction effect of (non-)
progressive feature, (non-) deterministic feature, and jackpot size on participants’ average
bet size (p < .05). The three-way interaction is illustrated in Figure 3.2. Like many three-way
interactions, this pattern of results is difficult to interpret. However, interactions can be
decomposed into a series of simple effects, only some of which are significant as pairwise
comparisons. When the jackpot was deterministic and large (Figure 3.2, Panel A),
participants placed higher bets on the EGM with non-progressive (M = 54.9 cents, SD =
23.3) rather than progressive jackpot (M = 38.0 cents, SD = 12.8, p < .05). In contrast, when
the jackpot was non-deterministic and large, the progressive feature was more likely to
contribute to large bet sizes, although the simple effects were marginally non-significant, p >
.05, ns.
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ProgressiveandDeterministicJackpots
Figure 3.2 Panel B shows the Average Bet Sizes for small jackpots ($500) in each condition
combination. For small jackpots, deterministic jackpots attracted larger bets than non-
deterministic; and non-progressive jackpots attracted higher bets than progressive jackpots.
Figure 3.2 Average Bet Size by (non-) progressive characteristic, (non-) deterministic
characteristic, and jackpot size (Panel A and B)
Panel A Panel B
3.8.3 Speed of betting (Bets per Minute)
The second ANCOVA model found no significant effects for the jackpot features
(progressive vs non-progressive and deterministic vs non-deterministic) on player betting
speed. Moreover, there were no significant effects for the interactions or covariates, with the
exception of PGSI status. Players with pre-existing gambling problems bet more slowly (M =
4.66, SD = 2.93) than players with few or no problems (M = 6.13, SD = 2.29), p < .05.
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3.8.4 Persistence (Total Trials Played)
The third ANCOVA model found no significant effects for the jackpot features (progressive
vs non progressive and deterministic vs non deterministic) on player persistence while
losing. All bets were programmed as losses past the 20th trial, but the jackpot feature did not
reliably predict continued play, nor did any interactions or covariates, p > .05.
3.8.5 Subjective Enjoyment
The fourth ANCOVA model showed no significant effects for the (non-) progressive
characteristic or the (non-) deterministic characteristic on participants’ subjective self-rated
enjoyment in playing the EGM, p > .05, ns. Moreover, the interaction and covariates also
proved non-significant, p > .05, ns.
3.8.6 Physiological Arousal (GSR/Skin Conductance)
A fifth ANOVA model used the change in skin conductance (GSR), subtracting average skin
conductance during play from a baseline period of 2 minute prior to play. There were no
significant effects for skin conductance (a physiological measure of player excitement) for
any of the jackpot features, interactions or covariates, p > .05, ns.
3.8.7 No-jackpot Condition
Each of the eight conditions in the factorial design was compared with the no-jackpot
condition through ANCOVA models using the conditions as the primary predictive variables
and gender, age, and PGSI as the covariates. None of the conditions were significantly
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different from the control for average bet size (all p’s > .05, ns), bets per minute (all p’s > .05,
ns), Total Trials (all p’s > .05, ns), subjective excitement (all p’s > .05, ns), or skin
conductance (all p’s > .05, ns).
3.9 Discussion
The present experiment sought to examine the effects of (non-) progressive and (non-)
deterministic jackpots on EGM playing behaviour, and how jackpot size may moderate such
effects. In a crossed-design, the results revealed a significant interaction between jackpot
size, the (non-) progressive feature and the (non-) deterministic feature on participants’
average bet size on the EGM. In particular, the largest bets were made on high jackpot
machines ($25,000) that were represented as deterministic (i.e., a payoff after x spins,
where x is determined at random) and non-progressive (i.e., for a fixed jackpot amount).
These machines may have appeared more valuable because of the ‘goal distance effect’.
The incremental bets may have encouraged larger bet sizes as the player felt they were
drawing nearer to an inevitable payoff event. Each bet places the gambler closer to the goal
of winning the jackpot prize. The experiment demonstrates that intensity of betting, at least
by measure of bet size, is largest in the presence of this type of jackpot. In fact, the average
bet size for the large, deterministic and non-progressive jackpot was 20.3% higher than the
bet-size average for all studied jackpot feature combinations (M = 54.9, SD = 23.3 vs M =
45.6, SD = 20.4).
Importantly, large jackpots that were non-deterministic (potential payoff determined at
random with each bet) and progressive (each bet adds to the jackpot prize) also promoted
high average bet sizes. This is a common configuration for jackpots in Australia as
measured in our observational study (see Chapter 7), and in this experiment demonstrated
bet-sizes are 18.4% higher than the average for all studied jackpot configurations (M = 54.0,
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SD = 27.9 vs M = 45.6, SD = 20.4). This jackpot configuration may be attractive for the
rolled-over effect that is hypothesised to make rolled-over lottery prizes more attractive
(Rogers, 1998). If players are lucky, large bets that add to the large jackpot prize can be
later recouped through a big win.
Consistent with Prospect Theory, larger prizes ($25,000) generally attracted higher bet sizes
than the smaller jackpot prizes ($500), although these differences were not significant as a
main effect. For smaller jackpot prizes, both deterministic (payoff after x spins, where x is
determined at random) and non-progressive (fixed $500 prizes) features attracted the
highest bet sizes.
3.10 Limitations
As is true for all lab-based experimental studies, there are concerns about the external
validity of the results. The artificial environment of the lab, as well as the way in which the
jackpots were described, may not be entirely true to the information player receive in a real
venue. Nevertheless, the jackpots were described in simple and functional language, and
these descriptions produced reliable effects on average bet size. We take the view of
experimental realism, where it is important to understand the psychological constraints and
contingencies that operate in real venues (including real money prizes), rather than
attempting to faithfully recreate every mundane detail of the gambling environment.
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3.11 Summary
This experiment provided some evidence that common jackpot configurations are associated
with higher average bet sizes, which are one component of gambling intensity. That such
jackpots configurations are relatively common in venues (see Chapter 7) is likely a
consequence of the natural evolution of EGMs, where only the most popular and profitable
machines survive competition on the gaming floor.
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3.12 References
Cook, P. J., & Clotfelter, C. T. (1993). The Peculiar Scale Economies of Lotto. The American
Economic Review, 83(3), 634-643.
Ferris, J., & Wynne, H. (2001). The Canadian Problem Gambling Index: Final Report:
Canadian Centre on Substance Abuse.
Johnson, E. E., Hamer, R. M., & Nora, R. M. (1988). The Lie/Bet questionnaire for screening
pathological gamblers: A follow-up study. Psychological Reports, 83(3 Part 2), 1219–
1224.
Kahneman, D., & Tversky, A. (1979). Prospect theory: An analysis of decision under risk.
Econometrica, 47(2), 263.
Kivetz, R., Urminsky, O., & Zheng, Y. (2006). The Goal-Gradient Hypothesis Resurrected:
Purchase Acceleration, Illusionary Goal Progress, and Customer Retention. Journal of
Marketing Research (JMR), 43(1), 39-58. doi:10.1509/jmkr.43.1.39
Rockloff, M., Hing, N. (2012). The Impact of Jackpots on EGM Gambling Behavior: A Review.
Journal of Gambling Studies. doi: 10.1007/s10899-012-9336-7
Rogers, P. (1998). The Cognitive Psychology of Lottery Gambling: A Theoretical Review.
Journal of Gambling Studies, 14(2), 111-134. doi: 10.1023/a:1023042708217
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Chapter 4: Experiment 2 Veiled Jackpots
EGM jackpots have structural characteristics that can potentially impact on the playing
behaviour of gamblers. In Chapter 3, an experiment revealed that specific structural
characteristics (Deterministic and Progressive) that describe how the jackpot is triggered can
have discernible and reliable influences on the bet-size of gamblers, even though the actual
triggering of jackpots is so rare as to be functionally irrelevant for players – and thus should
be largely irrelevant for their gambling choices and playing experience.
In this present experiment, another structural aspect of jackpots is explored to determine its
potential effects on the gambling decisions and enjoyment of players. In Veiled Jackpots the
triggering event mechanics are purposely obscured from the participants. Two types of
veiled jackpot features that are explored in this study are Hidden and Mystery jackpots.
4.1 Hidden Jackpots
In a hidden jackpot, the prize amount(s) is not shown to the player, although the existence of
a jackpot prize is advertised. This may cause some extra inducement and/or enjoyment for
players due to the unknown – and therefore potentially unlimited – value of the top prize.
Thus, by degree, the potential power of hidden jackpots relies on the potential
overestimation of the actual jackpot prize on offer. Of course, if players assume the jackpot
is likely to be smaller than the actual prize on offer, the attractiveness of hidden jackpots is
less. Therefore, the experiment will evaluate whether both suggestively large and small
hidden jackpots are more or less motivating and enjoyable than jackpots that are shown to
players.
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4.2 Mystery Jackpots
In a mystery jackpot, the “winning state” of the machine (e.g., combination of symbols) is not
shown to the players. Mystery jackpots can be a natural consequence of jackpot systems
that are independent of the core operation of the stand-alone EGM. Jackpot systems may be
added to several different types of machines, even machines from different manufacturers,
and thus each EGM bet is essentially a lottery draw for the grand prize of the jackpot
system. In a non-combinative mystery jackpot any losing sequence of symbols on the EGM
is just as likely to win the jackpot prize as a winning sequence, because the jackpot system
is essentially independent from the machine and uses the EGM only as a triggering device.
In contrast, a combinative mystery jackpot has a winning sequence of symbols on the
machine, but this combination is not shown to players prior to winning the jackpot.
For the purposes of the present experiment, the distinction between a non-combinative
mystery jackpot and a combinative mystery jackpot is not relevant. In both types of jackpots,
the “symbols” needed to win the jackpot are not known to the player and thus the
psychological effect on the player is equivalent.
4.3 Veiled Jackpots Experiment
The present study sought to investigate the effects of Hidden and Mystery Jackpots in an
experimental paradigm. Experiments offer a high degree of internal control, whereby the
effect of Veiled Jackpots can be reliably related to aspects of player behaviour. Veiled
jackpots are effective if players believe their expected value is in excess of the player
contributions to the jackpot. Thus, we had no prior expectations about whether hidden and
mystery jackpots should be effective in intensifying player behaviour or increasing
enjoyment.
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4.4 Method
4.4.1 Participants
One-hundred and seven (107) adults (58 female, 49 male) from Bundaberg QLD,
Rockhampton QLD and the surrounding Queensland areas responded to flyer
advertisements placed in local community newspapers (the Rockhampton Mirror, Capricorn
Coast Mirror, and Bundaberg News-Mail). Ages of participants ranged from 20 to 86 years
(M = 47.0, SD = 16.4). Cultural backgrounds of participants included: 74.8% Australian,
10.3% English, 3.7% Philippine, 2.8% New Zealander, and a further 8.4% of people
nominating another background (each less than 1% frequency). A further 4.7% of
participants (5) also identified as being Indigenous Australians. Eight-two percent (82%) of
the sample gambled on a casino style game at least once within the last 12 months.
4.5 Procedure
4.5.1 The Simulated EGM
Subjects played a 3 reel laptop simulated EGM created in Visual Basic (see Figure 4.1
below). The EGM was programmed with a fixed sequence of wins on trials 3, 4, 7, 12, 17,
19, 29, 36, 42, 48 and 50, and infinite losses thereafter. Reel size varied such that the six
icons (banana, 4 leaf clover, watermelon, horseshow, star and grapes) appeared with a
varied frequency per reel. Six icons were presented on reel 1 (once each), 9 icons on reel 2
and 12 on reel three. Consequently, we were able to ensure that the ‘winning combination’
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icons appeared relatively infrequently compared with other icons, ensuring that the
perceived probability of producing the winning combination was not artificially inflated.
Players were given $20 cash on arrival at their appointed time. After completing a brief
demographic questionnaire, participants were asked if they would like to wager their $20
compensation on the EGM. The $20 cash compensation was retrieved from the participants,
and participant played the EGM pre-loaded with 2000 in 1c credits. Subjects bet 25, 50 or
100 cents on each spin, and all wins paid x10 the amount bet for a theoretical maximum of
$120.25. The EGM produced the typical sights and sounds of EGM play, including the
musical sounds of spinning reals and winning bells.
Physiological measurements were taken as potential indicators of arousal and an excited
emotional state. Physiological arousal was measured via galvanic skin response (GSR)
using Biograph Infiniti software for participants 1-30 (Bundaberg), while similarly variations in
electrodermal activity (GSR) were measured using Affectiva Q-Sensor systems for the
Rockhampton sample (participants 31-107). Equipment availability necessitated using
different measurement apparatus at each site; however, all results reported below are robust
with respect to the study location / equipment.
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Figure 4.1. Simulated EGM depicting the jackpot amount and winning symbol
combination.
4.6 Conditions
Participants were assigned to conditions using a crossed design (see Table 4.1). Given the
modest sample size, stratified random assignment based on participants’ gender, age, and
Lie-Bet score was utilised to allocate participants to play the EGM in the different conditions
described below. Within four of these conditions, participants were presented with a potential
$500 cash jackpot in a mason-jar prior to play. Participants in a further four conditions were
presented a jackpot of 500 lottery tickets for a potential $25,000 prize (also shown in jar).
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The remaining participants in the control condition were not informed of any jackpot prize. All
participants, aside from those in the control condition, were told that someone in the
experiment would win the jackpot prize.
Table 4.1 Assignment of Subjects to Conditions.
Condition Cash Tickets Jackpot $
Hidden Jackpot $
Shown Combo
Mystery Combo
Known
1 9 9 9
2 9 9
9
3 9 9 9
4 9 9 9
5 9 9 9
6 9 9
9
7 9 9 9
8 9 9 9
9 N/A N/A N/A N/A N/A N/A
In another crossed condition, participants were assigned to either a “hidden” or “shown”
jackpot dollar value. All participants, aside from those in a control condition, were informed
that a jackpot could be won (cash or ticket value), but those in the hidden jackpot condition
were not informed of the monetary value of the jackpot. In a final crossed condition,
participants were assigned to either a known or mystery (unknown) winning-symbol
combination. All participants, aside from those in the control condition, were informed that
the jackpot would be won if a pre-determined combination of symbols appeared on screen,
but the winning combination was only revealed to those in the known combination condition.
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4.7 Results
4.7.1 Data Analysis
The primary outcomes were Average Bet Size, Speed of Betting (Bets per Minute),
Persistence (Total Trials Played), Self-rated enjoyment (1 item Likert 6 points), and
Physiological Arousal (GSR/Skin Conductance). For each outcome, the data analysis
calculated two models: a Full Factorial ANCOVA Model and a so-called Control ANCOVA
Model. The Full Factorial Model included all potential interactions between the Hidden and
Mystery Jackpot conditions, but consequently could not include the control condition (no
jackpots) as this latter condition necessarily could not be included in a crossed-jackpots
design. The Control ANCOVA model, in contrast, analysed each condition (as outlined in
Table 4.1) in a main-effects design without crossing conditions and included the no-jackpots
control condition.
4.7.2 The Full Factorial Model
ANCOVA models were run with each of these dependent measures and the crossed
conditions of Jackpot Prize ($500 Cash or 500 Instant Scratch Tickets), Jackpot Value
(Hidden or Shown) and Jackpot Combination (Known or Unknown) as the primary
independent variables. In addition, each model used Gender, Age and Dichotomised
Problem Gambling Severity Index Scores (PGSI 0, PGSI 1+) as covariates. The covariates
did not show any significant interactions with the other study variables.
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4.7.3 The Control ANCOVA Model
The no-jackpots control condition could not be analysed in a factorial model, and thus an
additional set of ANCOVAs models (the Control Models) were evaluated with Condition (1-9,
see Table 4.1) as the primary dependent variable, and Gender, Age and Dichotomised
Problem Gambling Severity Index Scores (PGSI 0, PGSI 1+) as covariates. No interactions
were used in these models. Fisher’s LSD was used to test for potential differences between
conditions.
4.7.4 Average Bet Size
As shown in Table 4.2, the outcome of Average Bet Size was not predicted by any of the
experimental conditions or model interactions, p > .05, ns. Nevertheless, PGSI status
approached significance, p = .055, whereby subjects with gambling problems had non-
significantly higher average bet sizes than those with no identifiable problems.
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Table 4.2 ANCOVA predicting Average Bet Size from Jackpot Prize ($500 Cash or 500
Instant Scratch Tickets), Jackpot Value (Hidden or Shown) and Jackpot Combination
(Known or Unknown)
Variable
df
MS
F^
Eta2
Prize ($500 Cash or 500 Instant Scratch
Tickets) 1 13.41 .03 .00
Value (Hidden or Shown) 1 123.78 .26 .00
Combination (Known or Unknown) 1 784.90 1.66 .02
Prize x Value 1 32.44 .07 .00
Prize x Combination 1 14.47 .03 .00
Value x Combination 1 5.91 .01 .00
Prize x Value x Combination 1 1150.67 2.43 .03
Age 1 1685.04 3.56 .04
Gender 1 507.66 1.07 .01
PGSI Status (PGSI 0, PGSI 1+) 1 1799.11 3.80 .04
Error 83 473.67
Total 94
^ no effects were significant at p < .05.
The Control Model assessed each of the 9 conditions of the experiment (see Table 4.1) as
the primary independent variable, with Age, Gender and Dichotomised PGSI as covariates.
Fisher’s LSD tests revealed no significant main effects between conditions for Average Bet
Size.
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4.7.5 Speed of Betting (Bets per Minute)
As shown in Table 4.3, the outcome of Speed of Betting (Bets per Minute) was not predicted
by any of the experimental conditions, p > .05, ns. However, PGSI status was significant, p
< .05, showing that gamblers with some problems bet at a higher rate of speed (M = 7.76
bets per minute, SD = 1.68) than gamblers with no problems (M = 7.16 bets per minute, SD
= 1.68), p < .05.
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Table 4.3 ANCOVA predicting Speed of Betting (Bets per Minute) from Jackpot Prize ($500
Cash or 500 Instant Scratch Tickets), Jackpot Value (Hidden or Shown) and Jackpot
Combination (Known or Unknown)
Variable
df
MS
F
Eta2
Prize ($500 Cash or 500 Instant Scratch
Tickets) 1 .60 .22 .00
Value (Hidden or Shown) 1 1.88 .69 .01
Combination (Known or Unknown) 1 .24 .09 .00
Prize x Value 1 2.59 .95 .01
Prize x Combination 1 1.40 .51 .01
Value x Combination 1 4.35 1.60 .02
Prize x Value x Combination 1 9.68 3.55 .04
Age 1 17.48 6.41 .07
Gender 1 1.79 .65 .01
PGSI Status (PGSI 0, PGSI 1+) 1 16.79 6.16* .07
Error 83 2.73
Total 94
* p < .05
The Control Model assessed each of the 9 conditions of the experiment (see Table 4.1) as
the primary independent variable, with Age, Gender and Dichotomised PGSI as covariates.
Fisher’s LSD tests revealed that in the conditions where the prize was 500 tickets and the
jackpot combination was shown, there was a significant higher betting speed for the hidden
$-value jackpot when compared to the shown $-value jackpot, p < .05 (see Figure 4.2).
Furthermore, in conformity with the prior Factorial Model, gambling problems (PGSI status)
again positively predicted Speed of Betting, p < .05.
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Figure 4.2 Betting Speed by Condition*
* Bars show Standard Errors
4.7.6 Persistence (Total Trials Played)
The number of trials played is a measure of gambling persistence, as all trials past 50 were
programmed with losses. There were no effects for the experimental conditions or
interactions on persistence, p > .05, ns (see Table 4.4). However, there was a significant
effect for PGSI status, such that subjects with some gambling problems (M Trials = 105.4,
SD = 54.0) bet for more trials than those with no problems (M Trials = 80.4, SD = 49.7), p <
.05.
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Table 4.4 ANCOVA predicting Persistence (Trials Played) from Jackpot Prize ($500 Cash
or 500 Instant Scratch Tickets), Jackpot Value (Hidden or Shown) and Jackpot Combination
(Known or Unknown)
Variable
df
MS
F
Eta2
Prize ($500 Cash or 500 Instant Scratch
Tickets) 1 656.07 .24 .00
Value (Hidden or Shown) 1 1069.430 .39 .01
Combination (Known or Unknown) 1 13.45 .01 .00
Prize x Value 1 9748.09 3.51 .04
Prize x Combination 1 22.75 .01 .00
Value x Combination 1 2535.82 .91 .01
Prize x Value x Combination 1 6711.94 2.42 .03
Age 1 2.76 .00 .00
Gender 1 2079.77 .75 .01
PGSI Status (PGSI 0, PGSI 1+) 1 23204.67 8.35* .09
Error 83 2778.82
Total 94
* p < .05
The Control Model assessed each of the 9 conditions of the experiment (see Table 4.1) as
the primary independent variable, with Age, Gender and Dichotomised PGSI as covariates.
In accord with the finding for Betting Speed, Fisher’s LSD tests revealed that in the
conditions where the prize was 500 tickets and the jackpot combination was known, there
was a significant higher persistence (Total Trials Played) for the hidden $-value jackpot
when compared to the shown $-value jackpot, p < .05. Moreover, this combination of the
ticket-jackpot and shown $-value combination had reliably higher persistence (Total Trials
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Played) than the no-jackpot control condition, p < .05; and the cash jackpot where the
jackpot value was hidden and the combination was shown, p < .05 (see Figure 4.3).
Figure 4.3 Persistence (Total Trials Played) by Condition
4.7.7 Self-rated Enjoyment
Subjects rated their enjoyment of the EGM on a 6 point Likert scale immediately after
playing. There were no significant effects for the experimental conditions, interactions or
covariates, p > .05, ns (see Table 4.5). Nevertheless, Gender approached significance, with
females (M = 4.63, SD = 1.09) marginally enjoying the EGM more than males (M = 4.13, SD
= 1.52), p = .051, ns.
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Table 4.5 ANCOVA predicting Enjoyment (6 point Likert item) from Jackpot Prize ($500
Cash or 500 Instant Scratch Tickets), Jackpot Value (Hidden or Shown) and Jackpot
Combination (Known or Unknown)
Variable
df
MS
F^
Eta2
Prize ($500 Cash or 500 Instant Scratch
Tickets) 1 2.51 1.40 .02
Value (Hidden or Shown) 1 2.14 1.19 .01
Combination (Known or Unknown) 1 .02 .01 .00
Prize x Value 1 1.57 .87 .01
Prize x Combination 1 .21 .12 .00
Value x Combination 1 .003 .00 .00
Prize x Value x Combination 1 .56 .31 .00
Age 1 .99 .55 .01
Gender 1 7.02 3.91 .05
PGSI Status (PGSI 0, PGSI 1+) 1 1.28 .71 .01
Error 83 1.80
Total 94
^ no effects were significant at p < .05. Gender approached the sig F of 3.96.
The Control Model assessed each of the 9 conditions of the experiment (per Table 4.1) as
the primary independent variable, with Age, Gender and Dichotomised PGSI as covariates.
Fisher’s LSD tests revealed no significant main effects between conditions for Self-rated
Enjoyment, p > .05, ns.
4.7.8 Physiological Arousal (GSR/Skin Conductance)
Physiological arousal was measured through GSR/Skin Conductance as the difference
between measurements during the experiment and a baseline 2-minute period immediately
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prior to the experiment. There was a significant main effect for the Combination (see Table
4.6), such that an unknown winning symbol combination (M = 0.273 standardised) produced
a greater increase in Physiological Arousal (GSR) than a known combination (M = -0.310
standardised).
Table 4.6 ANCOVA predicting Physiological Arousal (GSR/Skin Conductance) from
Jackpot Prize ($500 Cash or 500 Instant Scratch Tickets), Jackpot Value (Hidden or Shown)
and Jackpot Combination (Known or Unknown)
Variable
df
MS
F
Eta2
Prize ($500 Cash or 500 Instant Scratch
Tickets) 1 2.208 2.08 .02
Value (Hidden or Shown) 1 2.204 2.07 .02
Combination (Known or Unknown) 1 7.869 7.41* .08
Prize x Value 1 .429 .40 .01
Prize x Combination 1 .124 .12 .00
Value x Combination 1 .603 .57 .01
Prize x Value x Combination 1 .427 .40 .01
Age 1 .003 .00 .00
Gender 1 .060 .06 .00
PGSI Status (PGSI 0, PGSI 1+) 1 .007 .01 .00
Error 83
Total 94
* p < .05
The Control Model assessed each of the 9 conditions of the experiment (per Table 4.1) as
the primary independent variable, with Age, Gender and Dichotomised PGSI as covariates.
Fisher’s LSD tests revealed that the positive change is physiological arousal (GSR) was
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greatest for the Ticket jackpot where the jackpot $-value was shown ($25,000) but the
winning symbol combination was unknown. More generally, consistent with the Factorial
Model, the unknown “Mystery” winning symbol combination contributed to a greater positive
change in physiological arousal than the known combination (see Figure 4.4).
Figure 4.4 Physiological Arousal (GSR)
4.8 Discussion
The Full Factorial Models failed to show systematic effects for either Hidden Jackpots
(where the $ value is withheld) or Mystery Jackpots (where the winning combination is not
shown) on player behaviour, with the exception of the measure of Physiological Arousal
(GSR/Skin Conductance). Physiological arousal changes from the baseline period to the
experiment were most positive when the winning jackpot combination was a Mystery.
Therefore, there is some evidence to suggest that not showing a winning combination can
contribute to physiological arousal. In past research, physiological arousal has been
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associated with greater gambling intensity, but only if this experience is subjectively
interpreted as a positive emotion (Rockloff and Greer, 2010).
The Control ANCOVA Models revealed some detail on the specific jackpot combinations that
generally contributed to more intense gambling behaviour. In particular, the suggestively
large “ticket” jackpots where the $ value of the prize was hidden from players (i.e., not shown
on the EGM as the potential $25,000 top prize), but where the winning symbol combination
was displayed (a non-mystery) contributed to both the fastest gambling speeds (Bets per
Minute) and greatest persistence while losing (Total Trials Played). Speculatively, this may
have resulted from a subjective feeling that a winning combination was possible to achieve.
The jackpot symbols, while rare, did occasionally fall on the win line. This seemed to be
most attractive to players, however, when the top prize of the ticket jackpot was not known to
players – and therefore potentially very large. Importantly, the persistence of play in this
condition combination was greater than the control condition (no jackpot), suggesting that
large hidden value jackpots can contribute to gambling intensity – if accompanied by
advertised symbols that suggest such a win is possible. It is also noteworthy that although
non-mystery jackpots generally were associated with lower increases in physiological
arousal, the high-value hidden jackpots still had the highest increases in arousal within that
set.
4.9 Limitations
It is important to recognise the limitations of experiments in general with regard to threats to
external validity. This study did not attempt to faithfully recreate all the aspects of a real
gambling venue, but rather simulated the psychological contingencies that should act upon
real world decision making.
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It is possible that the findings can be somewhat sensitive to the specifics of operation for a
particular machine, as our machine occasionally (although rarely) showed the jackpot
winning symbol on the win-line. Nevertheless, these findings could be considered at least
indicative of a cause for concern for hidden jackpots that suggest high-value prizes.
4.10 Conclusion
This experiment demonstrated that suggestively large-value hidden jackpots (where the $
value prize is not shown, but might be considered high-value) potentially contributes to
intensive betting in the form of gambling speed and persistence; especially when a winning-
symbol combination suggests that such a win is possible. Thus, hidden jackpots may
deserve further scrutiny. There is no evidence here to suggest that such jackpots contribute
to greater player enjoyment, but nevertheless there is some preliminary evidence to suggest
a contribution of hidden jackpots to risky playing behaviour.
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4.11 References
Rockloff, M., & Greer, N. (2010). Never Smile at a Crocodile: Betting on Electronic Gaming
Machines is Intensified by Reptile-Induced Arousal. Journal of Gambling Studies, 1-11.
doi: 10.1007/s10899-009-9174-4
SurveyMonkey [Computer Software]. (1999). Portland, Oregon, USA.
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Chapter 5: Experiment 3 Socially Networked Jackpots
Linked jackpots draws can be won on several machines (often a bank of machines located in
close proximity) and the trigger of a jackpot win on one machine necessarily precludes a win
on another. Linked jackpots might be either shared only within the same venue (local area),
or shared across multiple venues (wide-area).
Linked Jackpots may artificially increase the perceived likelihood of winning a large prize
(Hare, 2010). Linked jackpots may also be more attractive through the offer of typically large
jackpot prizes, which are made possible by multiple contributing machines. However, it is
hitherto unknown whether the impact of linked jackpots on player optimism is greater when
jackpots are linked locally (within venues) or remotely (across venues). Evidence suggests
that gambling intensity is magnified by social motivations (Rockloff & Dyer, 2007; Rockloff &
Greer, 2010; Rockloff, Greer, & Evans, 2012; Rockloff, Greer, & Fay, 2010). The presence of
other gamblers vying for a locally linked jackpot may create a sense of urgency or
competition, thereby increasing EGM gambling intensity. However, Hing and Breen (2005)
found that the availability of linked jackpots linked across multiple venues might lead to
unrealistic optimism, which also contributes to gambling intensity.
5.1 Impact of Socially Networked Jackpots on Gambling Intensity and Player
Enjoyment
Socially Networked Jackpots allow for higher jackpot prizes with a smaller contributing
investment per machine. Thus, machines can still provide small wins and the potential for a
large jackpot prize. Socially Networked Jackpots can also introduce social factors into
gambling decisions, such as a perception of competition amongst players who are gambling
simultaneously. Of course, this same competition may exist on stand-alone jackpot
machines; however the player only relinquishes their attempt for the jackpot when they leave
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the machine. While playing, they have exclusive access to the potential jackpot. In Socially
Networked Jackpots, players compete for an available jackpot simultaneously. A long
research tradition in Social Facilitation shows that simultaneous competition intensifies
performance (Zajonc, 1965).
5.2 Socially Networked Jackpot Experiment
The present study sought to investigate the effects of Socially Networked Jackpots in an
experimental paradigm. Our primary outcomes were measures of gambling intensity,
including Average Bet Size, Speed of Betting (Bet per Minute), Persistence (Total Trials
Played), and Final Payouts (Wins/Losses). Additionally, we measured subjective player
enjoyment with a 1 item 6-point Likert item at the conclusion of the experiment. We had no a
priori hypotheses about which Socially Networked Jackpot (Linked or Wide-area) should
contribute to gambling intensity, as there was no strong theory or past findings that address
this comparison.
5.3 Method
5.3.1 Participants
One hundred and fifteen (114) subjects (female = 69, male = 45) from the Rockhampton city
and surrounding (QLD) areas responded to flyer advertisements placed in local community
newspapers (the Rockhampton and Capricorn Coast Mirrors). Ages ranged from 18 to 81
year (M = 40, SD = 18.13). One additional male participant elected not to continue after
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having completed the initial pre-gambling survey and was not included in the data set.
Seventy-two percent (72.6%) of participants identified as Australian, 6.2% as Filipino, 3.5%
as English, 2.7% as New Zealander, 2.7% as Chinese, 1.8% each from India and the United
States, and a further 8.9% as ‘other’. Additionally, 2 (1.8%) participants also identified as
being Indigenous Australians. Seventy four percent (74%) of the sample gambled on a
casino style game at least once within the last 12 months.
5.4 Procedure
5.4.1 The Simulated EGM
Subjects played a 3 reel laptop simulated EGM created in Visual Basic (see Figure 5.1
below). The EGM was programmed with a fixed sequence of wins on trials 3, 5, 11, 19, 25
and 34, and infinite losses thereafter. Players were given $20 cash on arrival at their
appointed time. After completing a brief demographic questionnaire, participants were asked
if they would like to wager their $20 compensation on the EGM. The $20 cash compensation
was retrieved from the participants, and participant played the EGM pre-loaded with 2000 in
1c credits. Subjects bet 25, 50 or 100 cents on each spin, and all wins paid x10 the amount
bet. The EGM produced the typical sights and sounds of EGM play, including the musical
sounds of spinning reals and winning bells.
Physiological measurements were taken as potential indicators of arousal and emotional
state. Physiological arousal was measured from galvanic skin response (GSR) using
Biograph Infiniti system and software.
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Figure 5.1 Simulated EGM depicting the jackpot amount.
5.5 Conditions
Participants were assigned to conditions using a crossed design (see Table 5.1). Due to the
small cell size in the experiment, randomised block assignment was used to assign
participants to condition based on a pre-experiment questionnaire answers on age, gender
and lie-bet score. Based on this random assignment, approximately 1/3 of participants were
presented with a potential $500 cash jackpot in a jar prior to play. A further 1/3 participants
were presented a jackpot of 500 lottery tickets for a potential $25,000 prize (also shown in
jar). A final 1/3 of participants were assigned to a control condition (no jackpot).
In another crossed condition, participants were assigned to either a Local Area Network
(LAN) or Wide Area Network (WAN) social group. In the LAN condition, participants were
lead into a room containing a group of 5 confederates posing as research volunteers whom
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each played a separate laptop-based EGM simulator. In the WAN condition, participants
were informed that they would be playing a remotely networked EGM along with five players
at another location. Participants in this condition were shown a simulated live video feed of a
group of five confederates playing in another room. All participants were told that someone
in the experiment would win the jackpot prize, and that the prize could be won on any
machine at any time (locally or remotely networked).
Table 5.1 Assignment of Subjects to Conditions
Condition Cash Tickets Control LAN WAN
1 9 9
2 9 9
3 9 9
4 9 9
5 9 9
6 9 9
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5.6 Results
5.6.1 Data Analyses
An ANCOVA model was calculated for each outcome, including Average Bet Size, Betting
Speed (Bets per Minute), Persistence (Total Trials Played), and Last Bank (Cash Out); as
well as Player Enjoyment measured with one 6 point Likert item and Skin Conductance
(GSR) measured with the Biograph Infinity System. Covariates for the models included Age,
Gender and Problem Gambling Status (PGSI Score).
5.6.2 Average Bet Size
The ANOVA results predicting Average Bet Size are shown in Table 5.2. The Prize variable
showed a significant main effect, whereby subjects shown the $500 cash jackpot had higher
bet sizes than those in the 500 ticket condition and the no-jackpot control condition (see
Figure 5.2).
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Table 5.2 ANCOVA predicting Average Bet Size from Jackpot Prize ($500 Cash or 500
Instant Scratch Tickets), Network (LAN or WAN)
Variable
df
MS
F
Eta2
Prize ($500 Cash, 500 Scratch Tickets, No
Prize) 2 1470.78 3.10* .06
Network (LAN or WAN) 1 272.53 .57 .01
Prize x Network 2 131.61 .28 .01
Age 1 136.38 .29 .00
Gender 1 1489.93 3.14 .03
PGSI 1 189.88 .40 .00
Error 104 475.08
Total 112
* p < .05.
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Figure 5.2 Average Bet Size by Jackpot Type
5.6.3 Speed of Betting
An ANCOVA model with Speed of Betting (in Bets per Minute) showed no significant effects
for either jackpot prize ($500 cash, 500 Tickets or No-jackpot Control), or Social Network
Type (LAN or WAN). However, the covariate of Age proved significant, p < .05, whereby
younger players bet faster than older gamblers (see Table 5.3).
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Table 5.3 ANCOVA predicting Speed of Betting from Jackpot Prize ($500 Cash or 500
Instant Scratch Tickets), Network (LAN or WAN)
Variable
df
MS
F
Eta2
Prize ($500 Cash, 500 Scratch Tickets, No
Prize) 2 2.53 .82 .02
Network (LAN or WAN) 1 10.82 3.53 .03
Prize x Network 2 .21 .07 .00
Age 1 83.27 27.13* .21
Gender 1 9.89 3.22 .03
PGSI 1 .14 .04 .00
Error 104 3.07
Total 112
* p < .05.
5.6.4 Persistence (Total Trials Played)
An ANCOVA model with Total Trials Played as the dependent variable showed no significant
effects for the experimental variables, interactions or covariates, p > .05, ns (see Table 5.4).
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Table 5.4 ANCOVA predicting Total Trials Played from Jackpot Prize ($500 Cash or 500
Instant Scratch Tickets), Network (LAN or WAN)
Variable
df
MS
F^
Eta2
Prize ($500 Cash, 500 Scratch Tickets, No
Prize) 2 454.66 .35 .01
Network (LAN or WAN) 1 2617.05 2.00 .02
Prize x Network 2 155.84 .12 .00
Age 1 234.32 .18 .00
Gender 1 3051.45 2.33 .02
PGSI 1 799.13 .61 .01
Error 104 1307.67
Total 112
^ No significant model effects at p < .05.
5.6.5 Last Bank
An ANCOVA model with Last Bank as the dependent variable showed no significant effects
for the experimental variables, interactions or covariate, p > .05, ns (see Table 5.5).
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Table 5.5 ANCOVA predicting Last Bank from Jackpot Prize ($500 Cash or 500 Instant
Scratch Tickets), Network (LAN or WAN)
Variable
df
MS
F^
Eta2
Prize ($500 Cash, 500 Scratch Tickets, No
Prize) 2 1752902.21 .91 .02
Network (LAN or WAN) 1 4010387.46 2.08 .02
Prize x Network 2 287480.24 .15 .00
Age 1 1388825.17 .72 .01
Gender 1 6181788.52 3.20 .03
PGSI 1 502592.81 .26 .00
Error 104
Total 112
^ No significant model effects at p < .05.
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5.6.6 Enjoyment
An ANCOVA model with Player Enjoyment (6 point Likert Item) as the dependent variable
revealed no significant effects for the experimental conditions or interactions, p > .05, ns.
However, the covariate of Gender was significant, such that Male subjects (M = 4.64, SD =
0.97) rated enjoyment of the simulated EGM as greater than Female participants (M = 4.00,
ASD = 1.61), p < .05 (see Table 5.6).
Table 5.6 ANCOVA predicting Enjoyment from Jackpot Prize ($500 Cash or 500 Instant
Scratch Tickets), Network (LAN or WAN)
Variable
df
MS
F
Eta2
Prize ($500 Cash, 500 Scratch Tickets, No
Prize) 2 1.37 .70 .01
Network (LAN or WAN) 1 .22 .11 .00
Prize x Network 2 1.62 .83 .02
Age 1 4.28 2.18 .02
Gender 1 9.97 5.09* .05
PGSI 1 2.26 1.15 .01
Error 104 1.96
Total 112
* p < .05.
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5.6.7 Physiological Arousal (GSR)
An ANCOVA model using GSR as the dependent measure found a significant effect for
Network Type, such that there was a greater increase in GSR for the WAN condition (M =
+0.197 standardised) than the LAN condition (M = -.254 standardised), p < .01 (see Table
5.7). Moreover, the covariate Age showed a significant effect, such that younger subjects
had greater positive changes in physiological arousal/GSR compared to older participants, p
< .01.
Table 5.7 ANCOVA predicting Skin Conductance/GSR from Jackpot Prize ($500 Cash or
500 Instant Scratch Tickets), Network (LAN or WAN)
Variable
df
MS
F
Eta2
Prize ($500 Cash, 500 Scratch Tickets, No
Prize) 2 1.07 1.34 .03
Network (LAN or WAN) 1 5.60 7.02** .06
Prize x Network 2 .07 .08 .00
Age 1 6.71 8.42** .08
Gender 1 1.29 1.62 .02
PGSI 1 .41 .51 .01
Error 104
Total 112
** p < .01.
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5.7 Discussion
The present experiment failed to show reliable evidence of differences between the WAN
and LAN conditions on Bet Size, Betting Speed, Persistence, Last Bank or Player
Enjoyment. Prior research has suggested that social facilitation, and in particular the sights
and sounds of other players winning, can motivate greater gambling intensity in groups.
However, the present experiment did not find any differences for these outcomes based on
whether others were immediately present or, alternatively, only present via a (fake) remote
video-conference feed. The only significant finding for Network Type was on change in
Physiological Arousal/GSR, whereby subjects in the WAN condition showed greater
increases in GSR to the LAN condition. However, this might be explained by the baseline
being performed with others present in the LAN condition, whereas the LAN video-feed
baseline was performed prior to starting the fake video-conference session.
5.8 Limitations
Failure to find significant effects for the LAN and WAN conditions cannot be taken as
evidence that there is no potential importance to the distinction between Local Area and
Wide Area jackpots on player behaviour or enjoyment. There may be a critical difference in
the social context within real venues compared to the context of the experiment. For
instance, players might feel a greater deal of either solidarity or competition with other local
and wide-area gamblers in real venues. Players who are members of a club, for instance,
may find a local-area jackpot more valuable, as other fellow club members are likely to be
the beneficiaries of an eventual payoff. Research on In-group/Out-group bias (Tajfel 1979)
consistently demonstrates favouritism towards an in-group, even when the groups are
composed on nominally irrelevant criteria (Billig and Tajfel, 1973). We purposefully did not
try to simulate group favouritism. Instead, this experiment simulated a neutral consideration
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of close or distant confederates. Future studies, however, might explicitly look at elements of
group prejudice that might potentially produce behavioural differences between jackpots that
are local or wide-area.
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5.9 References
Billig, M., & Tajfel, H. (1973). Social categorization and similarity in intergroup behaviour.
European Journal of Social Psychology, 3(1), 27-52.
Hare S. (2010). Player tracking and precommitment trial: A program and outcome evaluation
of the PlaySmart precommitment system. Schottler Consulting Pty Ltd. Retrieved from
www.treasury.sa.gov.au/public/download.jsp?id=3188
Hing, N., & Breen, H. (2005). Gambling amongst gaming venue employees: counsellors’
perspectives on risk and protective factors in the workplace. Gambling Research, 17(2),
25-46.
Rockloff, M., & Dyer, V. (2007). An experiment on the social facilitation of gambling behavior.
[10.1007/s10899-006-9042-4]. Journal of Gambling Studies, 23(1), 1-12.
Rockloff, M., & Greer, N. (2010). Audience Influence on EGM Gambling: The Protective
Effects of Having Others Watch You Play. Journal of Gambling Studies, 1-9. doi:
10.1007/s10899-010-9213-1
Rockloff, M., Greer, N., & Evans, L. G. (2012). The Effect of Mere Presence on EGM
Gambling. Journal of Gambling Issues. Journal of Gambling Issues.
Rockloff, M., Greer, N., & Fay, C. (2010). The Social Contagion of Gambling: How Venue
Size Contributes to Player Losses. Journal of Gambling Studies, 1-11. doi:
10.1007/s10899-010-9220-2
Tajfel, H. (81). Turner. JC (1979). An integrative theory of intergroup conflict. Social
psychology of intergroup relations, 33-47.
Zajonc, R. B. (1965). Social facilitation. Science, 149(3681), 269-274.
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Chapter 6: Experiment 4 Jackpot Expiry
EGM pre-commitment is a system whereby, prior to play, customers nominate a limit to their
maximum acceptable losses over a fixed period (e.g., 1 day or 1 week). Player behaviour is
tracked with a smart card or other identifying technology, and gamblers who exceed their
self-nominated loss limits are temporarily locked out of further gambling. This technological
solution may help people to adhere to self-imposed loss limits that they might otherwise be
tempted to exceed in the heat of play.
Mandatory pre-commitment insists that all players use the identification and tracking
technology to play EGMs; whereas optional pre-commitment allows people to optionally
avoid using the player tracking technology.
6.1 Jackpot Expiry Feature
One potential added benefit of pre-commitment is to use the embedded tracking technology
to target consumer protection features based on player behaviour. Jackpot Expiry is one
such added feature of mandatory pre-commitment introduced here, whereby players are
given a ‘soft brake’ on their gambling through a notification that they are no longer eligible for
jackpot prizes after a fixed amount of EGM play (e.g., 1 hour, 500 games, etc).
The presence of jackpots prizes can be a potent incentive to continue to gamble in the face
of mounting losses, as jackpots can provide a means of realising an instantaneous reversal
of fortunes. Thus, the presence of jackpots may be particularly motivating for a player with
large accumulated losses, as losing generally tends to make people more risk seeking with
respect to large low-probability gambles (Kahneman and Tversky, 1979).
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6.2 Validation of Jackpot Expiry
Jackpot Expiry must have a discernible impact on moderating EGM gambling intensity to be
effective. Aspects of player behaviour that are associated with long-run losses include:
higher average bet size, betting persistence while losing, and faster betting.
6.3 Jackpot Expiry Experiment
The present study sought to investigate the effects of Jackpot Expiry in an experimental
paradigm. Experiments offer a high degree of internal control, whereby the effect of Jackpot
Expiry can be reliably related to aspects of player behaviour. Our hypothesis was that during
an experimental gambling session with Jackpots that “expire”, players would exhibit lower
intensity gambling following expiry that leads to lower player losses. The experiment can
provide evidence for effectiveness of such a system for implementation as an added player
protection in a mandatory pre-commitment system.
6.4 Methods
6.4.1 Participants
One hundred and thirty volunteers (males = 56, females = 74) were recruited through
Bundaberg area newspaper flyers for an EGM experiment conducted between April and May
2013. The procedure for the experiment, detailed further below, involved presenting a
warning message in the test condition informing participants that a promised jackpot had
‘expired’ and could no longer be won. Thus, the behaviour of interest was player actions past
the presentation of the warning message, which was always shown on the 21st trial. Twenty-
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three (23) participants quit the EGM before reaching the 21st trial. These participants were
not informative on the influences of jackpot expiry, and thus were not included in the final
analysis. Participants who bet past the 20th trial totalled 107 people, including 45 males and
62 females. The cultural backgrounds of volunteers in the final sample were Australian
(78.5%), English (6.5%), Indigenous Australian (5.5%) and other backgrounds (9.5%) each
comprising less than 2% of the total. Problem gambling status, as computed from the
Problem Gambling Severity Index (PGSI, Ferris and Wynne, 2001), completed after the
experiment, included 55.1% no risk, 21.5% low risk, 18.6% moderate risk, and 4.6% problem
gamblers. Seventy percent (70%) of the sample gambled on a casino style game at least
once within the last 12 months.
6.5 Procedure
6.5.1 The Simulated EGM
Subjects played a 3 reel laptop simulated EGM created in Visual Basic (see Figure 6.1
below). The EGM was programmed with a fixed sequence of wins on trials 2, 6, 8, 13, and
20, and infinite losses thereafter. Players were given $20 cash on arrival at their appointed
time. After completing a brief demographic questionnaire, participants were asked if they
would like to wager their $20 compensation on the EGM. The $20 cash compensation was
retrieved from the participants, and participant played the EGM pre-loaded with 2000 in 1c
credits. Subjects bet 25, 50 or 100 cents on each spin, and all wins paid x10 the amount bet
for a theoretical maximum of $61.25. The EGM produced the typical sights and sounds of
EGM play, including the musical sounds of spinning reals and winning bells.
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Physiological measurements were taken as potential indicators of arousal and emotional
state using the Biograph Infinity System. Skin Conductance and skin temperature were
measured using wireless wristband sensor and sampled 8 times per second.
Figure 6.1 The Simulated EGM.
6.6 Conditions
Participants were assigned to conditions using a crossed design (see Table 6.1).
Randomised block assignment to condition was used to balance potentially important
covariates across condition. The blocking variables came from a pre-experiment
questionnaire, and included Gender, Age and Lie-bet scores. The randomised block
assignment was used to match approximately ½ of participants to being presented with a
potential $500 cash jackpot in a mason jar prior to play. The other ½ of participants were
presented a jackpot of 500 lottery tickets for a potential $25,000 prize (also shown in jar). All
participants were told that someone in the experiment would win the jackpot prize. In another
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crossed condition, subjects were presented with either: 1) a “relevant” message on the 21st
trial saying that the jackpot had expired and could no longer be won, 2) an “irrelevant” popup
message that simply said ‘click OK to continue’, and 3) a control condition with no popup
message.
Table 6.1 Assignment of Subjects to Conditions
Condition Cash Tickets Relevant Irrelevant Control
1 9 9
2 9 9
3 9 9
4 9 9
5 9 9
6 9 9
6.7 Results
6.7.1 Data Analysis
The primary behavioural outcomes of interest include average bet size, betting speed (bets
per minute) and persistence betting (total trials played), where each measure was calculated
past the 20th trial, and with the presentation of the Jackpot Expiry message in the test
condition. A direct measure of accumulated player losses past the 20th trial was also
included as a relevant outcome, as was Physiological Arousal/GSR.
Each outcome was analysed with an ANCOVA model using jackpot type (cash or tickets)
and message (relevant, irrelevant or control) as the primary predictive variables in a crossed
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design. Problem gambling status (PGSI), gender and age were entered as covariates only,
as none of these variables proved useful in producing significant interactions.
6.7.2 Average Bet Size
The average bet size was significantly smaller after trial 20 for subjects who were shown the
$500 cash jackpot (M = 43.2 cents, SD = 13.1) compared to those shown the ticket jackpot
(M = 51.1 cents, SD = 23.2), p = .02. Moreover, average bets were marginally higher for
players with 1 or more gambling problems (M = 50.9 cents, SD = 18.4) compared to those
with no identifiable problems (M = 44.6 cents, SD = 20.0), p = .05 (see Table 6.2).
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Table 6.2 ANCOVA predicting Average Bet Size from Jackpot Prize ($500 Cash or
500 Instant Scratch Tickets), and Message (Relevant, Irrelevant or Control)
Variable
df
MS
F
Eta2
Prize ($500 Cash, 500 Scratch Tickets) 1 2063.09 5.54* .05
Message (Relevant, Irrelevant or Control) 2 27.18 .07 .01
Prize x Message 2 72.28 .19 .00
Age 1 16.28 .04 .00
Gender 1 107.48 .29 .00
PGSI (0,1) 1 1468.74 3.95 .04
Error 98 372.20
Total 106
* p < .05.
6.7.3 Speed of Betting (Bets per Minute)
There were significant main effects for both jackpot type and message on the speed of
betting, p = .006 and p = .001, respectively (see Table 6.3). The cash jackpot had
significantly faster betting (M = 7.89 bets per minute, SD = 1.40) than the tickets jackpot (M
= 7.33 bets per minute, SD = 0.95), p = .006. Moreover, as shown in Figure 6.2, the speed of
betting was significantly slower in the “relevant” test condition compared to the control
condition, p = .001, and compared to the irrelevant conditions, p = .015.
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Table 6.3 ANCOVA predicting Speed of Betting from Jackpot Prize ($500 Cash or
500 Instant Scratch Tickets), and Message (Relevant, Irrelevant or Control)
Variable
df
MS
F
Eta2
Prize ($500 Cash, 500 Scratch Tickets) 1 9.30 7.78* .07
Message (Relevant, Irrelevant or Control) 2 9.63 8.05* .14
Prize x Message 2 1.83 1.53 .03
Age 1 3.51 2.94 .03
Gender 1 .91 .76 .01
PGSI (0,1) 1 .04 .03 .00
Error 98 1.20
Total 106
* p < .05.
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Figure 6.2 Speed of Betting by Message-Condition.
6.7.4 Total Trials Played
There was a significant main effect for age on the number of trials played after the 20th Trial,
with older players being more persistent in their betting than younger players (Partial Eta Sqr
= .046). There were no significant effects of jackpot type or message type on persistence as
measured by trials played (see Table 6.4).
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Table 6.4 ANCOVA predicting Total Trials Played from Jackpot Prize ($500 Cash
or 500 Instant Scratch Tickets), and Message (Relevant, Irrelevant or Control)
Variable
df
MS
F
Eta2
Prize ($500 Cash, 500 Scratch Tickets) 1 12.54 .01 .00
Message (Relevant, Irrelevant or Control) 2 2000.07 2.29 .05
Prize x Message 2 632.03 .72 .02
Age 1 4118.82 4.72* .05
Gender 1 143.23 .16 .00
PGSI (0,1) 1 13.22 .02 .00
Error 98 873.61
Total 106
* p < .05.
6.7.5 Losses past 20th Trial
There was a main effect for message type, such that the relevant message (withdrawing the
jackpot) reduced total losses for players, p = .033. Older participants lost more money, p =
.038, Eta = .043 (see Table 6.5). There was also a significant interaction between jackpot
type and message type, which is illustrated in Figure 6.3. The principal nature of the
interaction was smaller losses for the cash jackpot, compared to the ticket jackpot, when
subjects were shown the relevant Jackpot-expiry message.
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Table 6.5 ANCOVA predicting Total Trials Played from Jackpot Prize ($500 Cash
or 500 Instant Scratch Tickets), and Message (Relevant, Irrelevant or Control)
Variable
df
MS
F
Eta2
Prize ($500 Cash, 500 Scratch Tickets) 1 116.93 .84 .01
Message (Relevant, Irrelevant or Control) 2 493.33 3.54* .07
Prize x Message 2 120.51 .87 .02
Age 1 617.61 4.43* .04
Gender 1 79.37 .57 .01
PGSI (0,1) 1 238.65 1.71 .02
Error 98 139.40
Total 106
* p < .05.
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Figure 6.3 Losses Past Trial 20 by Incentive and Message Type
6.7.6 Enjoyment
An ANCOVA model was calculated with post-experiment rated Player Enjoyment (6 point
Likert item) as the dependent variable. There were no significant effects for the experimental
variables on player enjoyment and no covariates proved significant, p > .05, ns (see Table
6.6).
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Table 6.6 ANCOVA predicting Skin Conductance Change from Jackpot Prize
($500 Cash or 500 Instant Scratch Tickets), and Message (Relevant, Irrelevant or
Control)
Variable
df
MS
F^
Eta2
Prize ($500 Cash, 500 Scratch Tickets) 1 .08 .05 .00
Message (Relevant, Irrelevant or Control) 2 .82 .47 .01
Prize x Message 2 .78 .45 .01
Age 1 .76 .44 .00
Gender 1 3.86 2.22 .02
PGSI (0,1) 1 2.89 1.66 .02
Error 95 1.74
Total 103
^ no significant effects at p < .05.
6.7.7 Physiological Arousal (Skin Conductance)
There were no significant changes in baseline-to-test skin conductance by experimental
condition. Moreover, covariates were not significant predictors of skin conductance changes
(see Table 6.7).
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Table 6.7 ANCOVA predicting Skin Conductance Change from Jackpot Prize
($500 Cash or 500 Instant Scratch Tickets), and Message (Relevant, Irrelevant or
Control)
Variable
df
MS
F^
Eta2
Prize ($500 Cash, 500 Scratch Tickets) 1 .96 .91 .34
Message (Relevant, Irrelevant or Control) 2 1.17 1.11 .33
Prize x Message 2 2.13 2.02 .14
Age 1 1.55 1.47 .23
Gender 1 .34 .32 .57
PGSI (0,1) 1 2.40 2.27 .14
Error 95 1.06
Total 103
^ no significant effects at p < .05.
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6.8 Discussion
The present experiment sought to investigate the effect of Jackpot Expiry on player
behaviour by varying the messages shown to players on the 21st trial. In the test condition,
players were shown a “relevant” message stating that the promised jackpot had expired and
could no longer be won by the participant. In the irrelevant message condition a similar pop-
up message simply said to push the button to continue. Lastly, a control condition had no
pop-up message about the jackpot expiring.
The hypotheses were that Jackpot Expiry, as represented by the test condition, should
moderate behavioural indicators of gambling intensity. The results showed some evidence
that behaviour was modified by expired jackpots. First, bet speed was significantly slowed by
the jackpot expiry message compared to the irrelevant message condition and the no
message control condition. Perhaps most importantly, player losses past the 20th trial were
significantly reduced in the jackpot expiry condition, and the effect was most pronounced for
cash jackpots. Thus, we can conclude that there is experimental evidence to suggest that
jackpot expiry is likely to have a measurable effect in limiting player losses in the long run.
The physiological indicator of Skin Conductance did not show evidence for reliable changes
in physiological arousal. Speculatively, the influence of the messages may relate to cognitive
factors rather than emotional factors.
6.9 Limitations
Experiments are exposed to threats to external validity. Participants may not have reacted in
this experiment entirely in the same way they would in a real venue due to the different
environment and perceived contingencies in the artificial confines of the lab. Nevertheless,
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players were betting with real money and were allowed to keep their winnings, and thus,
some of the same psychological processes should still affect their behaviour. Moreover, the
directions of the effects were largely in agreement with a priori hypotheses.
6.10 Conclusion
The present experiment provides preliminary evidence to suggest that Jackpot Expiry could
be an effective means of providing a ‘soft brake’ for player behaviour as part of a mandatory
pre-commitment system. Jackpot expiry does not interrupt play and should have only a
modest effect on player enjoyment. In fact, highly intense betting – including betting in
excess of 2 hours in one session – is strongly related to gambling problems (Rockloff 2011).
Thus, jackpot expiry can be a targeted solution that preserves the entertainment value of
jackpots, yet removes the unwanted side-effect of encouraging gambling persistence among
players who are losing.
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6.11 References
Kahneman, D., & Tversky, A. (1979). Prospect theory: An analysis of decision under risk.
Econometrica, 47(2), 263.
Rockloff, M., Ehrich, J., Themessl-Huber, M., & Evans, L. (2011). Validation of a One Item
Screen for Problem Gambling. Journal of Gambling Studies, 1-7. doi: 10.1007/s10899-
010-9232-y
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Chapter 7: Shadowing Jackpots
In order to enhance the external validity of the experimental work described in previous
sections, we followed volunteer regular EGM players while they gambled in their customary
venues. This study allowed us to verify some aspects of our laboratory-based experimental
results in real venue settings. This involved the unobtrusive 'shadowing' of patrons and the
recording of aspects of their gambling behaviour in venues. After each session, we surveyed
attitudinal aspects relating to their play. We also examined, via behavioural and monetary
measures, whether jackpots have a stronger impact on gamblers who are already
experiencing problems. A structural analysis of the gaming session data is also presented.
The reader is directed to the literature review delivered in the first phase of this project for a
research literature background and theoretical context for this study.
7.1 Method
7.1.1 Participants
Arrangements were made with three major Australia gaming venues located in Queensland
and New South Wales to conduct research in their gaming areas. Research observers were
recruited from prior volunteers in prior experimental gambling research, as well as graduate
students, most of whom had substantive EGM playing experience. In total, 234 players (162
female) were recruited in-venue, and ‘shadowed’ (described in the next section) by research
assistants over the course of 442 EGM play sessions. Each participant was only followed
once, but some gamblers switched machines during the observation period. The median age
of participants was 58 years (M = 55, SD = 17.7). This is higher than the Australian
population median (37 years), which reflected the demographics of the venue clientele. Most
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of participants (N = 190, 81%) identified as having an Australian or New Zealand cultural
background, with the remainder split between European and Asian / sub-continental
nationalities. Eighty-seven participants (N = 87, 37%) had achieved year 12 or equivalent
qualifications, with a further 19 (8%) possessing a tertiary qualification. The median total
annual income was in the $20,800 - $31,199 bracket. Each participating player completed
the Problem Gambling Severity Index (PGSI) during the post-play survey (described below),
which is an established indicator of problematic gambling behaviour (Currie, Hodgins, &
Casey, 2013; Sharp et al., 2012). A mean PGSI score of 2.7 (SD = 4.5) was observed, with
140 (59%) participants scoring 1+, 47 (20%) scoring 5 or greater, and 21 scoring 8+ (9%).
7.2 Procedure
Observers attended the gaming lounges of each venue and invited players to participate in a
‘responsible gambling study’. Players were offered a $50 venue voucher, which was
redeemable for food and beverage purchases. Participants were informed that the aim of the
study was to observe how people played the poker machines. Data collection involved three
stages:
1. Pre-play survey and priming manipulation
2. Live observation of play
3. Post-play questionnaire
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7.3 Player-characteristics: pre-play survey and priming manipulation
During the pre-play survey, participants provided demographic survey information. At this
time, observers aimed to make the player as comfortable as possible, engaging in small-talk
and asking questions about the participants. This was considered an important process in
order to increase the likelihood of natural and uninhibited behaviour during subsequent live
observation of play.
Approximately 50% of participants, stratified by age and gender, were randomly assigned to
the priming condition. In contrast to the control, the priming condition involved the
administration of a further set of four open-answer questions that were designed to
encourage jackpot-oriented aspirational imagery. The items were preceded by the
statement: ‘Imagine that you won a Jackpot today. The lights are flashing and winning music
is playing.’ The questions were; ‘How would your life change?’, ‘Who would you want to
know about your good luck?’, ‘If you used the money for a trip, where would you go?’, and ‘If
you used the money to buy something else, what would you buy?’
7.4 Shadowing: Live observation of play
The observer explained to each player that playing in their normal manner would help
increase the reliability of the study. Players were asked to simply do what they were
originally intending to do in terms of EGM play before they were enrolled in the study.
Players were encouraged to play for as long or as little as they liked, and to move to different
machines or take breaks as they normally would. Observers followed players as they moved
through the gambling lounge. Observers stationed themselves at an optimal location near
the player so as to be close enough to observe play, but with care to not intrude on the
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player. Observers also chose a location where they could observe the EGM screen such that
their view was not occluded by the player, and further stood outside of the player’s field of
view. The recording procedure described below was repeated for each machine the player
visited.
7.5 Machine characteristics
At the outset of play on a particular EGM, observers commenced a new machine scoring
sheet, which included the full name of the EGM, e.g. ‘Queen of the Nile – Special Diamond
Edition’, and serial number of the machine. This information was used subsequently to
source further details of jackpots from the licensed monitoring operator. The following
information was also recorded:
1. Denomination: smallest bet size (in cents)
2. Linked jackpots: whether or not a wide area or local area network jackpot was
available
3. Jackpot advertising: either above the EGM itself, or above a bank of linked machines,
there may be a sign saying ‘Win $50,000’ or similar
4. Prizes: the displayed monetary value of each jackpot prize (up to 5 prizes) available
on the machine was recorded
7.6 Play characteristics
At the beginning and end of play on a particular EGM, the start and finish times were
recorded, allowing calculation of time-on-machine or play-persistence (‘Time’). Observers
noted funds deposited into the EGM each time players fed notes or coins into the machine,
for subsequent calculation of an aggregate ‘Money In’ measure. When playing the EGMs,
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players press the bet or credit button, then the lines button, which activates a particular bet /
reel-spin setting. Spins or plays are then usually repeatedly undertaken by pressing the
appropriate button. Monitoring this behaviour allowed observers to tally plays (trials played)
in an appropriate column of the scoring sheet (‘N. Plays’). Through appropriate column
weighting, an estimation of the number of credits lost during play was created. By combining
‘N. Plays’ with ‘Time’, an aggregate measure of plays per minute (‘Play Rate’) was also
produced.
Wins made by players during the session were also recorded by tallying the number of
occurrences in an appropriate column. The column categories were: $0.01-$2.00, $2.01-
$5.00, $5.01-$15.00. In the (relatively infrequent) case of wins in excess of $15.00, the
specific amount won was recorded in a separate column. This coding scheme allowed an
estimation of an aggregate ‘Money Won’ during play session-variable. Many modern EGMs
incorporate elaborations of basic play, such as the number of free spins and special
features. Accordingly, these were also monitored and tallied. However, variability in machine
functionality made it difficult to quantify the contribution of these play outcomes in the form of
credits won, and therefore was not incorporated into the ‘Money Won’ calculation. Finally,
when players finished their EGM session, the observer would record ‘Money Out’: the money
cashed out of the machine. The total money lost or won by the player was calculated by
subtracting ‘Money In’ from ‘Money Out’.
7.7 Results
Table 7.1 displays the summary statistics for both participant- and session-level numeric
variables in the study. On an average EGM session, participants lost an average of $4.20
over 10 minutes of play and 78 spins.
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Table 7.1 Summary statistics of numeric player and session variables
7.8 Total gambling time and EGM switching rate
As noted in the procedure, participants were encouraged to determine themselves the length
of time spent gambling, and decide which EGMs they wished to play. Many participants
played on only one machine during the monitoring period. However, some participants who
switched machines sometimes did so often, leading to positive skew in the distribution of
EGM session counts. The number of EGM sessions per participant ranged between 1 and
13, with a mean of 1.89 (SD=1.96). The average total time spent gambling per participant
over all EGMs was 9 minutes, with a SD of 9.5; also indicating positive skew (z = 2.6) in the
total gambling time per participant. The log-transformation of total time spent gambling
(‘Total Time’) was observed to be normal (skew z = 0.8). Therefore, this was used as the
response in an ordinary least squares (OLS) regression, with participants’ PGSI score, age,
and gender. We also considered whether the number of EGMs played during the session
varied systematically by participant characteristics. In this regression the response was a
count of EGMs played, and we used Poisson regression while controlling for the total time
observed gambling, which yielded an estimate of the rate at which players switched
machines. Table 7.2 summarises these two models, and shows that PGSI score and age
were positively related to total time spent gambling during the observation session. Age and
gender (male) were positively related to the rate at which participants switched EGMs.
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Table 7.2 Regression of player characteristics on rate of play: number of EGMs played
during the period (controlling for time spent gambling)
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7.9 Bivariate relationships between player and session characteristics
Bivariate correlations between EGM-session play characteristics, age, and participant PGSI
score are shown in Table 7.3. It illustrates that there were no significant univariate
relationships for age and PGSI score and play characteristics. Other significant relationships
are clearly due to intrinsic structural relationships between measures (e.g. Money Won and
N. Plays). Longer play duration (Time) was related to both the number of plays made (r =
.77) and a slower play rate (r = -.26). Play rate was negatively (r = -.16) related to money
taken out of the machine. This suggests that those players motivated to extending their
gaming experience often do so both by playing more slowly, by investing more funds, and
gambling until most or all funds were expended. The positive relationship between Money
Out and Time (.18) plus Money Out and N. Plays (.13) suggests that players who gambled
more persistently tended to leave the machine with more funds. This apparent paradox is
explained by a stronger relationship between Money Out and Money In (.30). We speculate
that some players are motivated to leave the machine ‘up’ (in the limited sense of
withdrawing funds after a win), and are willing to invest time and money to achieve this goal.
We caution that these bivariate results should be taken as an indication only, as they do not
take account of the distributional properties of the data and potential influencing covariates.
These will be addressed in the context of more specific questions via multiple regression and
path analysis in following sections.
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Table 7.3 Bivariate correlations between EGM session play characteristics, age, and
participant PGSI score
7.10 The effect of PGSI score and priming on EGM selection
Participants were free to choose which EGMs to play during the observation period. We
therefore considered the question of whether gambler characteristics led them to choose
machines that were more ‘jackpot-oriented’. In particular, we were interested in whether
those with gambling problems, and those who were primed with ‘big win’ aspirational
imagery, were more likely to be attracted to machines offering jackpots. The EGMs
considered offered a varying number (0 to 5) of jackpot prizes. Only 22 sessions involved
machines that had no jackpot at all. Jackpot prizes ranged from $10 to $56,443. Some
prizes were of unspecified amount (unadvertised). EGMs with multiple prizes tended to
follow a similar distribution of large to small prizes. This resulted in alternate ways in which
jackpot prizes could be characterised:
1. The total number of prizes offered (N. Prize)
2. The maximum prize offered, treating machine with only unadvertised prizes as
missing data (Max. Prize)
3. The number of prizes offered of advertised amount (N.Ad.Prizes)
4. The maximum advertised prize, treating machines with only unadvertised prizes as 0.
(Max. Ad. Prize).
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These characterisations were highly correlated. For example, the correlation between N.
Prize and Max. Prize was .72, indicating that machines with a larger maximum prize also
tended to offer more supplementary or minor prizes. However, since we did not have a prior
argument for preferring one parameterization over another, we present combined results for
all four characterisations of the jackpot machine characteristics. Table 7.4 presents
regression models predicting each of the four prize characteristics with gender, age, problem
gambling score (PGSI), and priming condition as explanatory variables, allowing for an
interaction between problem gambling score and priming condition. In this, and all
subsequent regression tables, bracketed values indicate 90% confidence intervals of the
parameter estimate. Because the number of prizes is an ordinal variable, models (1) and (3)
are cumulative link models, which estimate the cumulative odds of a player choosing an
EGM with a greater number of jackpot prizes as a function of the covariates. Ordinary least
squares (OLS) regression was used for models (2) and (4) on the log-transformed maximum
monetary prize.
The coefficient estimates in Table 7.4 shows that priming condition appeared to influence
selection towards both machines with a larger advertised prize, and also towards machines
with more prizes. Females may be marginally more likely to select machines with more or
larger prizes. There was an interaction between gambling problems and priming only in the
case of predicting the maximum advertised prize of the machine selected to play. Priming
showed a significant effect regardless of which jackpot feature was modelled. Coefficient
estimates were similar across jackpot feature, but the interaction effect between PGSI and
Priming was significant only for the maximum advertised prize measure. Therefore, we shall
next consider this effect in further detail using robust methods.
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Table 7.4 The relationship between participant characteristics and EGM selection. Models
corresponding to four alternative parameterisations of jackpot features are shown.
The relationship between priming, PGSI and attraction to jackpot machines can be made
clearer by dividing subjects according to the rule PGSI (no gambling problems) and
PGSI (at risk of gambling problems) as well as priming condition (prime or no-prime).
Table 7.5 shows the average maximum jackpot of machines selected by subjects in each of
the four resulting groups. Primed participants with gambling problems selected machines
with the highest average jackpots (M = $7,779), and un-primed participants without gambling
problems selected machines with the lowest average jackpots (M = $4,838). A post-hoc
non-parametric Wilcoxon rank sum test indicated that the differences between these two
groups was significant (W = 5560, p = .023). We further contrasted the primed, at-risk
condition to the three other conditions combined, also indicating a significant difference in
medians (W = 18423, p = .003). Finally, we confirmed the priming versus non-priming
contrast observed in the parametric model (W = 14337.5, p = .012), and found a similar
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marginally non-significant contrast for PGSI status (W = 11726.5, p = .065). These results
accord with the parametric effects observed for the maximum advertised prize, and we
therefore suggest that the combination of priming and elevated PGSI score did in fact lead
participants to select higher jackpot machines.
Table 7.5 Average maximum jackpot of EGM selected by participants by PGSI status and
priming manipulation.
7.11 Effects of PGSI and Jackpots on Money Invested and Number of Rounds Played
We were interested in whether or not PGSI and jackpots interacted to affect player
behaviour over play sessions. A single machine indicator of ‘jackpot-orientation’ was
required, as entering of multiple indicators was precluded by collinearity issues. N. Prizes
was selected (hereto after labelled ‘Jackpots’), as it possesses more suitable distributional
characteristics as a predictor in regression models than the (approximately exponentially
distributed) maximum advertised prize. Table 7.6 compares four models predicting Money In
(models 1 and 2) and N. Plays (models 3 and 4 using generalized linear models (GLMs)
assuming an error distribution proportional to the mean (Gamma) and a log-link). During
analysis, we compared several alternatives; the model structures reported here are the most
conservative in terms of estimation of effects. Alternative, less appropriate models (e.g.
those assuming constant-variance) tended to over-estimate the size of the effects of interest.
Further, the Gamma GLMs with a log-link appeared to possess the best model fit criteria in
terms of AIC and homogeneity of residuals.
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Table 7.6 Regressions of gambler and machine characteristics on funds invested (‘Money
In’) and Persistence (‘N. Plays’) during each session using log-normal and rank-order
regression.
Demographic variables Age and Gender were entered in all four models. The baseline
model for both response measures incorporated only main effects for PGSI, Jackpots and
Priming (models 1 and 3). The comparison models involved the addition of and associated
interaction terms (models 2 and 4). Models 3 and 4 controlled for Money In + Money Won on
the same scale as the response. In this context, available funds are a ‘nuisance’ variable
that we assumed to have a linear relationship on N. Plays.
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Table 7.6 indicates that players in general tended to invest more money in Jackpot-oriented
EGMs. Elevated PGSI scores were also associated with greater investment of funds. Men
tended to make fewer plays overall than women, and age was associated with more rounds
played. Those with higher PGSI scores tended to play fewer rounds in a single session
overall. However PGSI showed a significant positive interaction with Jackpots and Priming,
suggesting that at-risk gamblers responded to both priming and jackpots by playing more
rounds. As expected, the prime determinant of persistence was ‘available funds’, considered
as an aggregate of Money In and Money Won. We also considered a model which treated
log(Money In) and log(Money Won) as separate predictors, yielding significant parameter
estimates of .09 (SE = .027, t = 3.5) and .61 (SE = .021, t = 29.2), respectively. While not
affecting other parameter estimates, it is interesting because Money Won is a far better
predictor of N. Plays, despite the fact that the observational methodology entailed that
Money Won was measured with less precision than Money In. This indicates that the
‘available funds’ interpretation of the action of these variables is insufficient, since it implies
that Money In and Money Won are functionally equivalent and therefore should possess
similar parameter estimates. It rather suggests that players may interpret lack of wins as a
signal that the machine is ‘cold’, leading to the early termination of play. Conversely a
machine that is ‘paying off’ leads to greater persistence, leading to a tendency of players to
utilize funds won in-game to prolong their gambling session on the current machine.
7.12 Structural modelling of EGM session dynamics
The results above indicate the potentially complex interplay between the game/monetary
session variables, and motivated our use of a path analytic / model-comparison approach to
account for this covariability. All models were implemented using the ‘lavaan’ structural
equation modelling package in the R statistical programming environment (Narayanan,
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2012; Rosseel, 2012). As recommended by the package authors, the non-normality of the
data was handled by using robust standard errors based on a sandwich-type covariance
matrix (Browne & Arminger, 1995). The baseline path model (M0) assumed that funds
invested (Money In) financed more plays (N. Plays) and this in turn increased the amount of
winnings in the session (Money Won). According to this model, funds taken out of the
machine (Money Out) are a linear composite of the other three variables. N. Plays (being a
cost) should be negatively related to Money Out after other measures are taken into
account. M0 captures the known structural relationships in the game / monetary session
data, but explicitly does not include a positive feedback link between Money Won and Money
In. Thus, M0 assumes that players are not motivated to increase their session investment
based on session winnings. M1, shown in Figure 7.1, differed from M0 in allowing for this in-
session feedback effect (dashed line), which is shown to be significant and positive. All other
relationships were in line with expectations, including the direct and N. Plays and Money
Out. The AIC statistic (Vrieze, 2012) for M1 (AIC=31934) was superior that M0 (AIC=31977),
also indicating support for the inclusion of the feedback effect.
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Figure 7.1 Path model (M1) of game session variables illustrating structural feedback
(dashed line) of money won in-game (Money Won) to money invested (Money In)
We concluded that M1 presented a more accurate model of session-variable covariability,
and therefore explored the addition of PGSI and Jackpots as potential predictors of Money In
and N. Plays. Essentially, this amounted to a repeat of the regression analysis presented in
Table 7.6, using a more sophisticated covariance model. Preliminary analyses indicated that
Jackpots also significantly predicted N. Plays (z = 3.12, p = .002). However, structural
equation modelling demands careful consideration of alternate models (Kline, 2011), and in
doing so we concluded that on the basis of the current data, it was not possible to decide
upon the following alternative models:
a) Jackpots positively predict only N. Plays
b) Jackpots positively predict only Money In
c) Jackpots positively predict both N. Plays and Money In.
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As we shall discuss below, this model indeterminacy appears due to the structural links
between N. Plays, Money In, and Money Won. Based on the cross-sectional and
observational data at-hand, we are therefore restricted to the less specific conclusion, that
EGM Jackpots increase player engagement with the game, which may be manifested via
either increased spend or increased persistence.
7.13 Clustered observations over participant and EGM model
The structure of the session-level data analysed above involves limited clustering of samples
over observation sessions, including within participants, who played an average of 1.84
sessions under observation. There is also the potential for covariance between observations
made on the same EGM model (e.g. ‘Queen of the Nile’). However, due to the diversity of
EGMs in the market, repeated observations on similar models also occurred relatively
infrequently: an average of 2.05 sessions occurring on the same machine. We nevertheless
considered whether clustering of data affected the analyses of session-level data by
repeating the relevant session-level analyses using random-effects models (also known as
linear mixed-effects (LME) models). This framework accounts for the variance attributable to
the random factors ‘participant’ and ‘EGM’, and prevents Type II errors due to correlated
samples. We used the package ‘lmer’ (Bates, 2005) in the R statistical programming
environment (Team, 2011).
We found that, for the current data, the LME models produced fixed-effects estimates and
associated criterion probabilities that were substantially identical to the ordinary least-
squares (OLS) methods reported above. This was expected, given our small average cluster
sizes: LME estimates of fixed effects revert to their OLS counterparts as cluster sizes tend
towards 1. Given most readers are more familiar with OLS rather than LME statistical output,
and ordinal regression is not available for LME models, we have opted in this case to report
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only the output of the OLS models. Future research that employs sampling with a greater
degree of clustering may be useful to control for individual and machine differences, and in
this case an LME approach would be recommended.
7.14 Effects on money withdrawn at end of session
It can be argued that most behavioural play characteristics within a session can be efficiently
measured by a single variable: cash taken out at the end of the session. This is because the
amount of funds available at the end of the session is a deterministic function of: the money
put into the machine, money won during game (in terms of wins, special features, etc), and
the losses incurred. Since these measures in-turn capture player behaviour in terms of
number of plays made, a legitimate approach to understand the effect of machine
characteristics on player behaviour is to focus on the amount of funds taken out of the
machine at the end of the session. Essentially, this addresses the question of whether or not
machine characteristics such as jackpot prizes influence players to keep playing until all
funds (both stake and wins) are consumed, or alternatively cease play to withdraw funds
before they are entirely used. Most sessions end with a zero funds balance. However, when
money remains at the end of session, it is usually a function of wins (as shown in Figure
7.1), and is therefore subject to significant volatility, manifested as positive skew or over-
dispersion in the distribution. Table 7.7 presents two approaches to predicting this outcome;
a logistic model modelling the probability that remaining funds are non-zero, and a GLM
(Tweedie) model of the raw that accounts for both zero inflation and over-dispersion. We
found no effects significant at the .05 criterion. Although ‘Money Out’ is variable with high
personal impact on players, there are strong reasons to expect that intrinsically very high
variability of session-to-session winnings significantly reduces statistical power in detecting
effects on this variable.
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Table 7.7 Logistic (1) and Tweedie Models predicting Money Out from Session Variables
and Demographics
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7.15 Discussion
Player shadowing during EGM sessions yields behavioural and game data that cannot be
obtained via other (e.g. self-report) means. In contrast to experimental paradigms, the data
generated is unarguably ecologically valid; it arises from play with real money, on real
EGMs, in a real gambling venue. However, it also presents both methodological and analytic
challenges. Despite efforts to encourage participants to behave naturally, the psychological
impact of being ‘shadowed’ is probably significant, and may result in unmeasurable
alterations in play behaviour. Session variables such as N. Plays, Money In, Session Time,
and Money Out have the valuable property of being direct measures of session
characteristics. However, as described above, the behavioural / monetary session variables
represent a linked system, that is heavily influenced by Money Won in game. Since the
return distribution of EGMs is, by design, highly erratic; this creates a heavy injection of
noise that may obscure effects of interest. Experimental designs overcome this issue by
artificially creating a return distribution that is constant over sessions, and self-report
measures implicitly ‘average’ gambling outcomes over a large number of sessions within
individuals. Session data from real venues is often highly non-normal, demanding the use of
sophisticated statistical modelling methods that may be opaque to non-specialists. A final
challenge of an observational study is that game characteristics are determined by the
marketplace, which is generally geared towards optimisation of gambling intensity and
persistence. This may lead to poor sampling of the theoretical range of covariates. For
example in the present study, while a reasonable distribution of ‘less-jackpot oriented’ and
‘more jackpot oriented’ EGMs were observed, relatively few machines had no jackpots
whatsoever.
The present set of studies relied on experiments to investigate some specific structure
features of jackpots (e.g., deterministic jackpots), and an observational shadowing study to
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explore the motivational influence of jackpots in venue-based settings. Future research could
use the big-data gathered by EGMs to explore player behaviour on machines with different
types of jackpots, and potentially provide more ecologically valid information on structural
features. This would avoid the potential bias introduced by overt observation, and could even
yield player-level information with the aid of player tracking technologies (e.g., smart cards).
Despite the methodological hurdles, the present shadowing study yielded some useful
results that could not obtained by other means. PGSI score was not associated with faster
switching between EGMs, but high PGSI gamblers were found to spend a longer total time
gambling during their visit to the gambling venue. This suggests that extended total gambling
time may be an indicator of gambling problems, and is a useful result, considering that this is
a behaviour that may be unobtrusively observable by venue staff.
Priming participants reliably influenced the selection of jackpot-oriented machines. The
parametric modelling yielded ambivalent results regarding a possible interaction between
PGSI and Priming. However, contrasting low-risk (PGSI<5) versus at-risk gamblers
(PGSI>4) via non-parametric post-hoc tests indicated that Priming and PGSI status jointly
contribute to a greater attraction towards jackpot-oriented machine. These results suggest
that jackpots appeal to motivations associated with the anticipated outcomes of play in terms
of the life changes a large win might create; and further that at-risk gamblers appear to be
more influenced by these cognitions.
Jackpot-oriented machines were reliably associated with a greater spend, which is also
consistent with the marketplace offering most EGMs with jackpots. It is plausible that, as with
other ‘bonus features’, these create the psychological perception of greater interest and
excitement. A related perspective is that traditional EGM play without jackpots promotes
player spend in order to continue to experience the relatively common wins. Jackpots
(though almost never realised) adds a qualitatively different extra aspect of ‘aspirational’
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motivation. This interpretation accords with our findings regarding priming, jackpots, and
machine selection.
Although findings from the regression analysis reported in Table 7.6 suggest that jackpots
affect spend but not persistence, further investigations built upon the path analytic model
suggest this distinction should be treated with caution. When Jackpots are introduced as a
predictor of the responses Money In and/or N. Plays, a significant positive association is
found (using appropriate robust or bootstrapped standard errors) with one or both of the
responses, depending on whether Money Won is included as a feedback variable affecting
either or both of the responses. Model fit criteria of the alternative models are not
significantly different. We are therefore prevented from deciding upon one of these models
as the ‘correct’ model, as a result of the covariability of N. Plays and Money In, and the
strong potential feedback effect of in-game winnings. Our conclusion is therefore that
jackpots positively affect player engagement with the game. However, further investigation is
required to delineate whether this is reflected in increased spend (and thereby increased
play), increased play (independent of spend), or both.
Higher PGSI scores were generally related to fewer plays/spins per EGM session. This may
be due to the fact that higher PGSI players tended to gamble using higher credits per play
and therefore consumed funds faster. This interpretation is supported by the observation that
PGSI was associated with a greater spend per EGM session. Importantly, significant
interactions were observed between PGSI and Jackpots, as well as PGSI and Priming. The
persistence of higher PGSI players was therefore differentially affected by both experimental
and machine factors thought to induce an ‘aspirational’ cognitive state. Most previous
research has indicated that problem gamblers ‘know they are not going to win’, and are
rather thought to be attached to the experience of play itself. Jackpots and Priming do not
impact the experience of play itself (except in the very rare case of a Jackpot win), but are
instead conceptualized as heightening motivation via aspirational cognitions and emotions.
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Therefore, this potential alternate motivational mechanism, that appears to operate
differentially for higher PGSI players, is an interesting finding that should be explored further.
A final contribution of this study is to explore the manner in which observable session
variables; Money In, N. Plays, Money Won, and Money Out; are related functionally to one
another, as shown in Figure 7.1. The fitted model shows that our observations accord with a
basic property of gambling known to every casual observer: that further spins increase take-
home money through wins, but this is outweighed by the cost of each spin. However it also
demonstrates more subtle properties of EGM play. The direct link between Money In and
Money Out is not-significant, suggesting that invested funds are almost always entirely
consumed through play. Funds left at the end of the session are therefore driven primarily by
the random return distribution of re-invested credits. Via model comparison, it was also
demonstrated that money won in game motivated further investment of funds. Thus, a player
experiencing wins may actually be at risk of losing more money over the longer term, as the
‘motivational feedback’ effect tends to increase the amount of money put into the machine
over the longer term. With these results in mind, it is not surprising that we did not find
significant effects of player or machine characteristics predicting Money Out. We suspect
this is firstly because it is an indirect measure of player behaviour (directly observable via
Money In and N. Plays). Secondly, as demonstrated by the structural model, the effects of
these variables on Money Out are mediated by the highly random EGM return distribution,
as well as possible feedback loops. Thus, ‘Money Out’ appears not to be driven by
psychological variables, but rather by the intrinsic EGM return distribution, which is known to
be highly random with constant mean. One advantage of applying path analysis would be to
control for covariances between observable session variables when treating one or more of
them as a response in a regression model. This might be accomplished in future work, by
either working with residuals of the fitted path model, or alternatively expanding the system
to include other observed and latent measures of machine or individual characteristics.
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