Luke Clark

• Managing Director at University of British Columbia

Modern slot machines can create immersive experiences for gamblers. Design features, including audiovisual cues, may influence these experiences, potentially interacting with personal risk factors for disordered gambling. According to the incentive salience hypothesis of addiction, reward-paired audiovisual cues strongly motivate behavior. This stu...

Background Loot boxes are randomized reward mechanics in modern video games that share features with conventional gambling products. Research studies have begun to test longitudinal patterns (“migration”) from engagement with loot boxes to gambling behavior. This study investigated such effects at a 6-month follow-up in an online sample of young ad...

Background: Loot boxes are randomized reward mechanics in modern video games that share features with conventional gambling products. Research studies have begun to test longitudinal patterns (‘migration’) from engagement with loot boxes to gambling behavior. This study investigated such effects at a 6-month follow-up in an online sample of young a...

Chasing refers to the escalation of betting behaviour. It is conventionally seen when losing but can also be seen after wins. Diagnostic and screening items for gambling problems describe chasing as returning ‘another day’ to gamble. However, gamblers may also chase within sessions, and this is particularly relevant in online gambling. This study f...

Betting more after losses (i.e., “loss‐chasing”) is a central clinical feature of disordered gambling. According to prospect theory, increasing risk‐seeking following losses could arise from a failure to “re‐reference.” By contrast, successful re‐referencing between successive decisions closes the mental account, and any losses are regarded as fina...

Objective: Near-misses are a structural characteristic of gambling products that can be engineered within modern digital games. Over a series of preregistered experiments using an online slot machine simulation, we investigated the impact of near-miss outcomes on subjective ratings (motivation, valence) and two behavioral measures (speed of gamblin...

Background and aims This study characterized chasing behaviour as the time to return to an online gambling website after a losing or a winning visit. Methods We analyzed a naturalistic dataset from an eCasino ( PlayNow.com , the provincial platform for British Columbia, Canada), comprising 1,909,681 sessions from 15,544 individuals. Analyses disti...

The Post-Reinforcement Pause (PRP) is an operant effect in which response latencies increase on trials following the receipt and consumption of reward. Human studies demonstrate analogous effects in electronic gambling machines that utilise variable ratio reinforcement schedules. We sought to identify moderators of the human PRP effect, hypothesizi...

Background Individuals with cocaine use disorder or gambling disorder demonstrate impairments in cognitive flexibility: the ability to adapt to changes in the environment. Flexibility is commonly assessed in a laboratory setting using probabilistic reversal learning, which involves reinforcement learning, the process by which feedback from the envi...

Objective: The purpose of this research was to assess factors (i.e., emotion regulation, impulsivity) that motivate in-play sports betting. Specifically, we examined whether individuals report increased excitement after placing an in-play bet and whether trait negative and positive urgency moderate the effect of emotion regulation motives on in-pla...

Open science refers to a set of practices that aim to make scientific research more transparent, accessible, and reproducible, including pre-registration of study protocols, sharing of data and materials, the use of transparent research methods, and open access publishing. In this commentary, we describe and evaluate the current state of open scien...

Betting more after losses (i.e. ‘loss chasing’) is a central clinical feature of disordered gambling. According to Prospect Theory, increasing risk-seeking following losses could arise from a failure to ‘re-reference’. By contrast, successful re-referencing between successive decisions closes the mental account, and any losses are regarded as final...

Chasing refers to the escalation of betting behaviour. It is conventionally seen when losing (loss chasing) but can also be seen after wins. Diagnostic and screening items for gambling problems describe chasing as returning ‘another day’ to gamble, i.e. between-session chasing. However, gamblers may also chase outcomes within sessions, and this may...

Objective: Near-misses are a structural characteristic of gambling products that can be engineered within modern digital games. Over a series of pre-registered experiments using an online slot machine simulation, we investigated the impact of near-miss outcomes, on subjective ratings (motivation, valence) and two behavioural measures (speed of gamb...

The ability to learn about other people is crucial for human social functioning. Dopamine has been proposed to regulate the precision of beliefs, but direct behavioural evidence of this is lacking. In this study, we investigate how a high dose of the D2/D3 dopamine receptor antagonist sulpiride impacts learning about other people’s prosocial attitu...

Open science refers to a set of practices that aim to make scientific research more transparent, accessible, and reproducible, including pre-registration of study protocols, sharing of data and materials, the use of transparent research methods, and open access publishing. In this opinion piece, we describe and evaluate the current state of open sc...

Cognitive flexibility refers to the ability to adjust to changes in the environment and is essential for adaptive behavior. It can be investigated using laboratory tests such as probabilistic reversal learning (PRL). In individuals with both Cocaine Use Disorder (CUD) and Gambling Disorder (GD), overall impairments in PRL flexibility are observed....

The structural addictive characteristics of gambling products are important targets for prevention, but can be unintuitive to laypeople. In the PictoGRRed (Pictograms for Gambling Risk Reduction) study, we aimed to develop pictograms that illustrate the main addictive characteristics of gambling products and to assess their impact on identifying th...

Cross-sectional studies have established a robust correlational link between loot box engagement and problem gambling, but the causal connections are unknown. This longitudinal study tested for ‘migration’ from loot box use to gambling initiation 6-months later. A sample of gamers (aged 18–26) was stratified into two subgroups at baseline: 415 non-...

Financially focused self-concept has been linked to gambling problems among people who gamble. Herein, we examined the bifactor structure of the 20-item financially focused self-concept scale (FFS), which includes one global factor and four grouping factors (self-views, feelings, interpersonal relationships, achievement). We examined the convergent...

Modern slot machines are among the more harmful forms of gambling. Psychophysiological measures may provide a window into mental processes that underpin these harms. Here we investigated pupil dilation derived from eye tracking as a means of capturing changes in sympathetic nervous system arousal following outcomes on a real slot machine. We hypoth...

Habit formation is a key process in contemporary models of addictive behaviors but has received limited attention in the context of gambling and problem gambling. Methods for examining habit formation and expression in relation to gambling are also lacking. In this study, 60 participants with no prior slot machine experience attended three sessions...

The Pathways Model of problem gambling has become a highly influential framework in the field of gambling studies. This special issue commemorates 20 years since the publication of the original paper, highlighting the sustained impact of the Pathways Model across the broader and emergent field of behavioral addictions. As a framework, the Pathways...

Nower et al. [1] report new data on the pathways model of problem gambling that substantiate the original 3 ‘subtypes’ and clarify some nuances of the original model. Despite a strong assertion that the model was intended to describe clinically relevant heterogeneity among those with gambling problems, we suggest this neo-Kraepelinian assumption is...

Concerns regarding the similarities between video game ‘loot boxes’ and gambling have been supported by correlations in survey studies between loot box engagement and problem gambling scores. It is generally noted that this correlation could reflect loot box users migrating to conventional gambling, and/or people with gambling problems being attrac...

Gambling involves monetary bets and prizes, but the money can take a range of formats, including cash, chips, ticket-in ticket-out vouchers, and digital options including banking cards. As societies move toward cashless payment for many goods, the question arises of how emerging payment technologies might impact gambling-related harms. We performed...

Purpose of review: Problematic engagement in slot machine gambling has been linked to a state of immersion: heightened attention on the activity (i.e. gambling) at the expense of other mental processing. This review considers the relevance of this state to substance-related addictions, and other behavioural addictions besides disordered gambling. W...

The incentive sensitization theory of addiction proposes that through repeated associations with addictive rewards, addiction-related stimuli acquire a disproportionately powerful motivational pull on behaviour. Animal research suggests trait-like individual variation in the degree of incentive salience attribution to reward-predictive cues, define...

Advances in cashless technologies create a dilemma for gambling regulators. Research indicates that cash purchases entail a ‘pain of paying’ that is attenuated with more abstract forms of payment, yet limited research has directly tested the impact of mode of payment on gambling behavior. Across two experiments, community-recruited gamblers were ra...

E. J. Langer's paper, 'The illusion of control' (1975), showed that people act in ways that suggest they hold illusory beliefs in their ability to control the outcome of chance-determined games. This highly cited paper influenced the emerging field of gambling studies, and became a building block for cognitive approaches to problem gambling. Over t...

Purpose of Review The slot machine zone describes a ‘trance-like’ state of diminished attention to time passing and gambling-irrelevant events during Electronic Gaming Machine (EGM) use. This article summarizes two prominent theoretical accounts of this state and articulates a new account that seeks to integrate them. Recent Findings Zone experien...

The Pareto effect (also known as the 80/20 rule) describes a skewed distribution of engagement that is observed for many products. In this study, we investigated Pareto estimates for online casino gambling, and tested their association with voluntary self-exclusion (VSE) as a marker of gambling harm, and examined their sensitivity to varying time w...

Humans seek admiration to boost their social rank and engage in rivalry to protect it when fearing defeat. Traits such as narcissism and affective states such as depression are thought to influence perception of rank and motivation for dominance in opposite ways, but evidence of the underlying behavioral mechanisms is scant. We investigated the eff...

Background and aims Individuals with gambling disorder display increased levels of risk-taking, but it is not known if it is associated with an altered subjective valuation of gains and/or losses, perception of their probabilities, or integration of these sources of information into expected value. Methods Participants with gambling disorder ( n =...

The identification of disordered gambling in the online environment may enable interventions to be targeted to those users experiencing harms. We tested the performance of machine learning in classifying online gamblers with and without a record of voluntary self-exclusion (VSE). We analyzed a one year dataset from PlayNow.com, the provincially own...

Counterfactual thinking is a component of human decision-making that entails “if only” thinking about unselected choices and outcomes. It is associated with strong emotional responses of regret (when the obtained outcome is inferior to the counterfactual) and relief (vice versa). Counterfactual thinking may play a role in various cognitive phenomen...

Humans seek admiration to boost their social rank and engage in rivalry to protect it when fearing defeat. Traits such as narcissism and affective states such as depression are thought to influence perception of rank and motivation for dominance in opposite ways, but evidence of the underlying behavioral mechanisms is scant. We investigated the eff...

Flow activities (e.g. sports and gaming) have been associated with positive affect and prolonged engagement. In the gambling field, modern electronic gaming machines (EGMs, including modern slot machines) have drawn concern as a potentially flow-inducing activity that may be associated with gambling-related harms. Current research has heavily relie...

Rationale Gambling and alcohol use are recreational behaviours that share substantial commonalities at a phenomenological, clinical and neurobiological level. Past studies have shown that alcohol can have a disinhibiting effect on gambling behaviour, in terms of bet size and persistence. Objectives This study was conducted in order to characterise...

Background and aims: The Pathways Model (Blaszczynski & Nower, 2002) posits that problem gambling is a heterogeneous disorder with distinct subgroups (behaviorally conditioned gamblers, emotionally vulnerable gamblers, and antisocial-impulsivist gamblers). Impulsivity traits and gambling-related cognitions are recognized as two key psychological f...

Background and aims: Immersion during slot machine gambling has been linked to disordered gambling. Current conceptualizations of immersion (namely dissociation, flow, and the machine zone) make contrasting predictions as to whether gamblers are captivated by the game per se ('zoned in') or motivated by the escape that immersion provides ('zoned o...

Psychological and neurobiological markers in individuals with gambling disorder (GD) could reflect transdiagnostic vulnerability to addiction or neuroadaptive consequences of long-term gambling. Using an endophenotypic approach to identify vulnerability markers, we tested the biological relatives of cases with GD. Male participants seeking treatmen...

Background: Previous research has indicated that disordered gamblers display deficits in impulsivity and risky decision-making, compared to healthy control groups. However, disordered gamblers are not a homogenous group, and differences in performance on neurocognitive tasks may be related to the form of gambling in which an individual chooses to e...

Background The U.S. National Institutes of Mental Health Research Domain Criteria (RDoC) seek to stimulate research into biologically validated neuropsychological dimensions across mental illness symptoms and diagnoses. The RDoC framework comprises 39 functional constructs designed to be revised and refined, with the overall goal to improve diagnos...

Gambling has longstanding links with excitement and physiological arousal, but prior research has not considered (a) gamblers’ ability to detect internal physiological signals, or (b) markers of parasympathetic functioning. The present study measured interoception in individuals with gambling disorder, using self‐report measures and a heartbeat cou...

Impaired decision-making has recently gained recognition as a component of the suicidal diathesis. Yet, although precipitants and particularly deterrents to suicidal behavior are often interpersonal, little is known about social decision-making in suicidal individuals. This study employed a novel version of the Ultimatum Game to investigate how emp...

Narcissistic individuals rely on achieving dominance over others to keep an intact self-esteem (Rhodewalt 1998, J. Pers. Soc. Psychol.). Yet, few experimental studies investigated the social decision-making in narcissism, none of them examining the effects of social defeat specifically. We describe a social defeat manipulation and validate it again...

Altered decision making processes and excessive risk-seeking behaviours are key features of conduct disorder (CD). Previous studies have provided compelling evidence of abnormally increased preference for risky options, higher sensitivity to rewards, as well as blunted responsiveness to aversive outcomes in adolescents with CD. However, most studie...

Electronic Gaming Machines (EGMs) are regarded as a relatively harmful gambling product, and are associated with psychological immersion (the 'machine zone') and physiological arousal. Specifically, immersion is a phenomenon of attention manifesting as an intense focus on the game at the expense of peripheral stimuli and goals. Past research has in...

Neuroscience research on gambling, including neuropsychological, neuroimaging, and psychophysiological experiments, is often regarded as aligned with the ‘brain disease model of addictions’. We assert that a bio-psycho-social framework represents the consensus view of disordered gambling, giving equal weighting to biological and psychosocial predis...

Gambling may constitute a strategy for coping with depressive mood, but a direct influence of depressive mood on gambling behaviors has never been tested via realistic experimental designs in gamblers. The current study tested whether experimentally-induced sadness increases persistence on a simulated slot machine task using real monetary reinforce...

Increased cognitive distortions (i.e. biased processing of chance, probability and skill) are a key psychopathological process in disordered gambling. The present study investigated state and trait aspects of cognitive distortions in 22 individuals with Internet Gaming Disorder (IGD) and 22 healthy controls. Participants completed the Gambling Rela...

Stopping devices are a structural characteristic of modern slot machines that enable the player to brake the spinning reels manually, but with no influence on the predetermined outcome. This study tested two mechanisms for why players might use a stopping device: (1) enhanced ‘illusory control’, and (2) faster game speed. Thirty student participant...

Conspicuous consumption refers to the phenomenon where individuals purchase goods for signalling social status, rather than for its inherent functional value. This study (n = 166 male participants) investigated how the outcome of a social competition influenced conspicuous consumption, and its association with competition-induced testosterone react...

Testosterone has been linked to social status seeking in humans. The present study investigated the effects of testosterone administration on implicit and explicit preferences for status goods in healthy male participants (n = 64), using a double-blind, placebo-controlled, between-subjects design. We also investigated the interactive effect between...

Conspicuous consumption refers to the phenomenon where individuals purchase goods for signalling social status, rather than for its inherent functional value. This study (n = 166 male participants) investigated how the outcome of a social competition influenced conspicuous consumption, and its association with competition-induced testosterone react...

Research on gambling near-misses has shown that objectively equivalent outcomes can yield divergent emotional and motivational responses. The subjective processing of gambling outcomes is affected substantially by close but non-obtained outcomes (i.e. counterfactuals). In the current paper, we investigate how different types of near-misses influenc...

Serotonin has been implicated in promoting self-control, regulation of hunger and physiological homeostasis, and regulation of caloric intake. However, it remains unclear whether the effects of serotonin on caloric intake reflect purely homeostatic mechanisms, or whether serotonin also modulates cognitive processes involved in dietary decision maki...

Recent accounts of problematic electronic gaming machine (EGM) gambling have suggested attentional pathology among at-risk players. A putative slot machine zone is characterized by an intense immersion during game play, causing a neglect of outside events and competing goals. Prior studies of EGM immersion have relied heavily upon retrospective sel...

Neuroscientific explanations of gambling disorder can help people make sense of their experiences and guide the development of psychosocial interventions. However, the societal perceptions and implications of these explanations are not always clear or helpful. Two workshops in 2013 and 2014 brought together multidisciplinary researchers aiming to i...

Serotonin has been implicated in promoting self-control, regulation of hunger and physiological homeostasis, and regulation of caloric intake. However, it remains unclear whether the effects of serotonin on caloric intake reflect purely homeostatic mechanisms, or whether serotonin also modulates cognitive processes involved in dietary decision maki...

Cue reactivity is an established procedure in addictions research for examining the subjective experience and neural basis of craving. This experiment sought to quantify cue-related brain responses in gambling disorder using personally tailored cues in conjunction with subjective craving, as well as a comparison with appetitive non-gambling stimuli...

Cue reactivity is an established procedure in addictions research for examining the subjective experience and neural basis of craving. This experiment sought to quantify cue-related brain responses in Gambling Disorder using personally tailored cues in conjunction with subjective craving, as well as a comparison with appetitive non-gambling stimuli...

Illusory control refers to an effect in games of chance where features associated with skilful situations increase expectancies of success. Past work has operationalized illusory control in terms of subjective ratings or behaviour, with limited consideration of the relationship between these definitions, or the broader construct of agency. This stu...

As a behavioural addiction, gambling disorder (GD) provides an opportunity to characterize addictive processes without the potentially confounding effects of chronic excessive drug and alcohol exposure. Impulsivity is an established precursor to such addictive behaviours, and GD is associated with greater impulsivity. There is also evidence of GABA...

Near-misses occur across many forms of gambling and are rated as unpleasant while simultaneously increasing the motivation to continue playing. On slot machines, the icon position relative to the payline moderates the effects of near-misses, with near-misses before the payline increasing motivation, and near-misses after the payline being rated as...

Gambling is a harmless, recreational pastime that is ubiquitous across cultures. However, for some, gambling becomes a maladaptive and compulsive, and this syndrome is conceptualized as a behavioural addiction. Laboratory models that capture the key cognitive processes involved in gambling behaviour, and that can be translated across species, have...

Illusory control refers to an effect in games of chance where features associated with skilful situations increase expectancies of success. Past work has operationalised illusory control in terms of subjective ratings or behaviour, with limited consideration of the relationship between these definitions, or the broader construct of agency. This stu...

Backgrounds and aims Problem gambling occurs at higher levels in the homeless than the general population. Past work has not established the extent to which problem gambling is a cause or consequence of homelessness. This study sought to replicate recent observations of elevated rates of problem gambling in a British homeless sample, and extend tha...

Figure S1: Sensitivity of peripheral responses in male versus female participants. Appendix S1: Internal consistency of peripheral responses Table S1: Estimation of internal consistency of peripheral responses. Appendix S2: Posterior model fit. Figure S2: Posterior model fit of data shown in Figure 2. Figure S3: Posterior model fit of data sho...

A contribution to a special issue on Hormones and Human Competition. Social competition is associated with marked emotional, behavioral and hormonal responses, including changes in testosterone levels. The strength and direction of these responses is often modulated by levels of other hormones (e.g. cortisol) and depends on psychological factors –...

Social competition is associated with marked emotional, behavioral and hormonal responses, including changes in testosterone levels. The strength and direction of these responses is often modulated by levels of other hormones (e.g. cortisol) and depends on psychological factors – classically, the objective outcome of a competition (win vs. loss) bu...

Loss aversion is a defining characteristic of prospect theory, whereby responses are stronger to losses than to equivalently sized gains (Kahneman & Tversky Econometrica, 47, 263-291, 1979). By monitoring electrodermal activity (EDA) during a gambling task, in this study we examined physiological activity during risky decisions, as well as to both...

Near-misses in gambling games are losing events that come close to a win. Near-misses were previously shown to recruit reward-related brain regions including the ventral striatum, and to invigorate gambling behavior, supposedly by fostering an illusion of control. Given that pathological gamblers are particularly vulnerable to such cognitive illusi...

Background and aims Precommitment refers to the ability to prospectively restrict the access to temptations. This study examined whether risk-taking during gambling is decreased when an individual has the opportunity to precommit to his forthcoming bet. Methods Sixty individuals participated in a gambling task that consisted of direct choice (simp...

The current study assessed peripheral responses during decision making under explicit risk, and tested whether intraindividual variability in choice behavior can be explained by fluctuations in peripheral arousal. Electrodermal activity (EDA) and heart rate (HR) were monitored in healthy volunteers (N = 68) during the Roulette Betting Task. In this...

Using a rodent slot machine task (rSMT), we have previously shown that rats, like humans, are susceptible to the reinforcing effects of winning signals presented within a compound stimulus array, even when the pattern generated predicts a negative rather than a positive outcome such as during a “near-miss”. The dopamine D4 receptor critically media...

Alterations in reward processes may underlie motivational and anhedonic symptoms in depression and schizophrenia. However it remains unclear whether these alterations are disorder-specific or shared, and whether they clearly relate to symptom generation or not. We studied brain responses to unexpected rewards during a simulated slot machine game in...

In addition to the symptoms of inattention, hyperactivity, and impulsivity, individuals with attention deficit hyperactivity disorder exhibit impaired performance on tests of real-world cost/benefit decision-making. Atomoxetine, a nonstimulant drug approved for the treatment of attention deficit hyperactivity disorder, is a selective norepinephrine...

Addiction;arousal;decision-making;gambling;interoception;nicotine;smoking

Loss aversion is a defining characteristic of prospect theory, whereby responses are stronger to losses than to equivalently sized gains (Kahneman & Tversky Econometrica, 47, 263–291, 1979). By monitoring electrodermal activity (EDA) during a gambling task, in this study we examined physiological activity during risky decisions, as well as to both...

Pathological gambling is a psychiatric disorder and the first recognized behavioral addiction, with similarities to substance use disorders but without the confounding effects of drug-related brain changes. Pathophysiology within the opioid receptor system is increasingly recognized in substance dependence, with higher mu-opioid receptor (MOR) avai...

Billieux et al. (2015) propose that the recent proliferation of behavioral addictions has been driven by deficiencies in the underlying research strategy. This commentary considers how pathological gambling (now termed gambling disorder) traversed these challenges to become the first recognized behavioral addiction in the DSM-5. Ironically, many si...

Human choice under uncertainty is influenced by erroneous beliefs about randomness. In simple binary choice tasks, such as red/black predictions in roulette, long outcome runs (e.g. red, red, red) typically increase the tendency to predict the other outcome (i.e. black), an effect labeled the “gambler’s fallacy.” In these settings, participants may...

As a popular form of recreational risk taking, gambling games offer a paradigm for decision neuroscience research. As an individual behavior, gambling becomes dysfunctional in a subset of the population, with debilitating consequences. Gambling disorder has been recently reconceptualized as a "behavioral addiction" in the DSM-5, based on emerging p...

Impairments in inhibitory control characterize a range of addictive behaviors including gambling disorder. This study investigated the relationship between a neuropsychological measure of inhibitory control and behavior on a simulated slot machine that included a measure of gambling persistence, in a non-clinical sample of regular gamblers. Regular...