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Mere ownership effect is the phenomenon that people tend to value what they own more than what they do not own. This classic effect is considered robust, yet effect sizes vary across studies, and the effect is often confused for or confounded with other classic phenomena, such as endowment or mere exposure effects. We conducted a pre-registered meta-analysis of 26 samples published before 2019 (N = 3024), that resulted in psychological ownership on valuing effect of g ~ 0.55 [0.43, 0.66]. Suggestive moderator analyses supported the use of replica and valuing type as the strongest moderators. Mere ownership effects were different from the null across all moderator categories and in most publication bias adjustments. We consider this as suggestive evidence that psychological owning leads to valuing, yet caution that much more research is needed. All materials, data, and code are available on https://osf.io/fdyqw/
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Mere ownership effect: Meta-analysis
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Owning leads to valuing:
Meta-analysis of the Mere Ownership Effect
*Michał Białek
Institute of Psychology
University of Wrocław
Wrocław, Poland
michal.bialek3@uwr.edu.pl / mihalbialek@gmail.com
https://orcid.org/0000-0002-5062-5733
*Yajing Gao
Department of Work and Social Psychology
Maastricht University
Maastricht, 6200MD, The Netherlands
yajing_gao1993@163.com
*Donna Yao
dan.yao819@gmail.com
*^Gilad Feldman
Department of Psychology
University of Hong Kong
Hong Kong SAR
gfeldman@hku.hk
In press at European Journal of Social Psychology
Accepted for publication on June 30, 2022
*Equal contribution, joint first author
^Corresponding author
Word count - Abstract: 152; Manuscript: 7660 words
Mere ownership effect: Meta-analysis
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Author Bios:
Michał Białek is an associate professor of psychology with the University of Wrocław. His research
focuses on decision making under conflicting cues (e.g., moral, intertemporal, risky choice).
Yajing Gao is a graduate of the Maastricht University work and social psychology department masters
program. For her thesis under the guidance of Gilad Feldman she conducted a pre-registered replication
and pre-registered meta-analysis of ownership effect.
Donna Yao was a research associate with the Department of Management at Lingnan University in Hong
Kong.
Gilad Feldman is an assistant professor with the University of Hong Kong psychology department. His
research focuses on judgment decision-making.
Declaration of Conflict of Interest:
The author(s) declared no potential conflicts of interests with respect to the authorship and/or publication
of this article.
Financial disclosure/funding:
The author(s) received no financial support for the research and/or authorship of this article.
Acknowledgments or Author Notes:
We would like to thank Siu Kit Yeung and Adrien Fillon for their help reviewing the code and the
manuscript and their remarkable work on the open Meta Analysis Registered Report templates and
support throughout our meta-analysis process. We would like to thank Ignazio Ziano and Farid Anvari for
helpful comments on drafts of this manuscript.
Authorship declaration:
Yajing worked under the supervision of Gilad at Maastricht University for conducting the pre-registered
meta-analysis as part of Yajing's masters thesis. Yajing wrote the pre-registration, with verification and
registration by Gilad. Yajing conducted the search of the literature. Gilad developed the coding scheme.
Yajing and Gilad pre-tested the coding sheet. Yajing and Gilad coded the articles. Gilad wrote the initial
RMarkdown code and analyses. Yajing summarized the methods and results and wrote an initial draft.
Donna and Michał updated and verified analyses and results. Michał and Gilad wrote the final journal
submission draft.
Data availability statement:
All data/code/materials were made available on the OSF: https://osf.io/txnsk
Ethics approval statement:
Ethical approval not needed for this project. A meta-analysis.
[Patient consent statement: Not relevant, meta-analysis. Permission to reproduce material from other
sources: Not relevant.]
Mere ownership effect: Meta-analysis
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Abstract
Mere ownership effect is the phenomenon that people tend to value what they own more than
what they do not own. This classic effect is considered robust, yet effect sizes vary across
studies, and the effect is often confused for or confounded with other classic phenomena, such as
endowment or mere exposure effects. We conducted a pre-registered meta-analysis of 26
samples published before 2019 (N = 3024), that resulted in psychological ownership on valuing
effect of g ~ 0.55 [0.43, 0.66]. Suggestive moderator analyses supported the use of replica and
valuing type as the strongest moderators. Mere ownership effects were different from the null
across all moderator categories and in most publication bias adjustments. We consider this as
suggestive evidence that psychological owning leads to valuing, yet caution that much more
research is needed. All materials, data, and code are available on https://osf.io/fdyqw/
Keywords: ownership; mere ownership effect; meta-analysis; psychological ownership; valuing
Mere ownership effect: Meta-analysis
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Owning leads to valuing:
Meta-analysis of the Mere Ownership Effect
One of the authors recently offered candies to his children, one chocolate and one
strawberry flavored. Although the children received candies that were not in line with their stated
preferences, they refused to trade the candies. This is an illustration of the mere ownership
effect: people generally hold more positive evaluations (e.g., set higher prices) or exhibit
stronger liking towards an owned object, relative to an object that is not owned (e.g., Barone,
Shimp, & Sprott, 1997; Beggan, 1992; De Dreu & van Knippenberg, 2005; Morewedge et al.,
2009; Peck & Shu, 2009).
A core element of the mere ownership effect is psychological ownership, the perception
that an object is owned by oneself, representing a perceived association between an individual
and an object (Heider, 1958). Once an association is formed, the object is then perceived to be
associated with the self and may therefore carry attributes related to one's definition of the self
(Belk, 1988). As people tend to perceive themselves in a more positive way than how they
perceive others (Taylor, 1989), this tendency often extends to self-associated objects, resulting in
more favorable evaluations of owned objects relative to not-owned objects (Beggan, 1992).
Ownership has been shown to be relevant to the understanding of the psychological
underpinnings of legal and moral rules guiding our social environment with most prominent
examples of exchange and trade (Nancekivell, Friedman, & Gelman, 2019). Keeping track of
ownership is even considered by some to be a reason as to why writing and numbers were
developed (Schmandt-Besserat, 1986).
Mere ownership effect: Meta-analysis
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In this project we were interested in examining the mere ownership effect, estimating its
effect size, and testing potential boundary conditions. To this end we present a meta-analysis of
the mere ownership effect, and consider several potential moderators, including the type of
objects (actual vs. replica; material vs. immaterial object), type of ownership (legal vs. no clear
legal ownership; implicit vs. explicit ownership; same vs. different exposure), consequences of
owning an object (potential loss vs. no potential loss), experimental design choices (between-
subjects vs. within-subjects design), and measurement category (evaluation vs. price).
We begin by reviewing the literature on the mere ownership effect, defining the scope of
our review of the phenomenon, discussing the importance of the effect and how it relates to and
differs from other similar psychological constructs. We then report a pre-registered meta-analysis
and discuss findings and implications.
Mere Ownership Effect
The mere ownership effect is the phenomenon that people tend to value what they
perceive to own more than what they perceive not to own. An experimental illustration of this
effect was first presented by Beggan (1992). Participants in one of his experiments were
presented with cold drink insulators and eight other objects. Next, they were asked to judge the
attractiveness of all products. Some of the participants were promised to receive the insulator as
a gift, whereas others would either receive an object of similar value or receive nothing. The
ratings of the insulator differed across the three groups. Participants that were promised to
receive the insulator rated it as more attractive, valuable, and better designed, compared to
participants in the other two groups. Hence, the conclusion was that people liked the promised
object more because they perceived it as already being theirs.
Mere ownership effect: Meta-analysis
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Why does the mere ownership effect occur? There are several suggested accounts. From
an evolutionary perspective, people may like objects that they own more because this may help
them trade with greater profit margins, thus giving them an advantage over individuals who
would not attach greater value to owned objects and would therefore not convincingly bargain
for higher prices (Huck, Kirchsteiger, & Oechssler, 2005). Individuals that are more strongly
subject to the mere ownership effect may be able to acquire more resources in trading compared
to those less prone to the effect, hence being in a better position to have more offspring and
better support them, thereby having an advantage in transmitting their genes to the next
generation. The preference for one’s own possessions has been observed in early stages of life,
as young as two-to-three years old children (Gelman, Manczak, & Noles, 2012), which may
indicate that this tendency is hardwired into human cognition.
Greater valuation of owned objects may also emerge because, compared to objects that
are not owned, features of owned objects seem more cognitively readily available (Johnson,
Häubl, & Keinan, 2007), and these tend to be price-increasing positive features (reliable, well-
maintained, etc.) (Ashby, Dickert, & Glöckner, 2012). In comparison, when people consider
potential purchases, evaluating something they do not yet own, they tend to think about price-
decreasing features first (such as weaknesses, risks, potential failures and break-downs).
Therefore, the subjective value of an object depends on the features that one thinks about and
considers which in turn depend on ownership and perspective (Johnson, Häubl, & Keinan, 2007).
Mere Ownership and Endowment Effects: Loss Aversion
In the economics literature, changes in valuations of owned objects in a transaction were
labelled as an endowment effect (Thaler, 1980; Marzilli Ericson & Fuster, 2014). For example,
Korobkin (2003) defines the endowment effect as a case when “people tend to value goods more
Mere ownership effect: Meta-analysis
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when they own them than when they do not” (pp. 1228). The phenomenon is often demonstrated
by comparing willingness to accept (WTA) to willingness to pay (WTP) in a situation of buying
and/or selling (Knetsch, 1989; Franciosi, et al., 1996).
Thaler (2015) illustrated the endowment effect by describing the endowment behavior of
a friend who collected wine. This friend only bought relatively inexpensive wine (up to $30).
After some time, some of the wine collected became much more expensive with prices reaching
over $100. The friend refused to sell his wine for the high market price, and at the same time
refused to buy similar wine for this much. Thaler concluded that the wine was simultaneously
worth over and under $100. Consistent with this observation, a meta-analysis of the endowment
effect found that the WTA to WTP ratio is roughly 2.6, i.e., that the asking price is between
double to triple the bidding price (Horowitz & McConnell, 2002).
One of the possible explanations for the endowment effect is that people react differently
to gains and losses. In a phenomenon coined as "loss aversion", the negative affect experienced
as a result of a loss is perceived to be stronger than the positive affect experienced as a result of
an equivalent gain (Kahneman & Tversky, 1984; Tversky & Kahneman 1991). Sellers/owners
perceive selling goods as a loss, and buyers/non-owners perceive buying an object as a gain
(Thaler, 1980; Kim & Johnson, 2015; Knetsch, Tang and Thaler, 2001; Peck & Shu, 2009; Sen
& Johnson, 1997). Since people are aversive to losses, sold goods seem to have greater value
than bought goods (Tversky & Kahneman, 1991). Korobkin (2003) argued that on top of a “pure
loss aversion there is also an attachment to an object which results in discomfort with the idea
of subjecting an object to a market transaction. Considering the above, it is possible that people
set a higher price for an owned object in a transaction because they weigh the anticipated
Mere ownership effect: Meta-analysis
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negative feelings of forgoing the object against the weaker positive feelings associated with
potential monetary gains.
Another possible explanation for the endowment effect is the status quo bias: the
preference for the status quo, all other things being equal (Samuelson & Zeckhauser, 1988).
Sellers perceive owning the object as the familiar effortless status quo, and the departure from
the object as an effortful somewhat uncertain change to the current state (Thaler, 1980; Brenner
et al., 2007). Hence, the generalized biases of loss aversion and the status quo bias may jointly
explain the endowment effect in transaction situations (Korobkin, 2006).
Despite similarities between the mere ownership effect and the endowment effect, the
two effects are mostly studied in separate literatures, with little acknowledgment and cross-
referencing. Whereas economics and marketing literatures mainly focused on the endowment
effect (or WTA-WTP differences), the social, personality, and organizational psychology
literatures mostly focused on mere ownership effect and psychological ownership. In several
meta-analyses of WTA-WTP asymmetries (Sayman & Öncüler, 2005; Tunçel & Hammitt, 2014)
there were no references to the mere ownership literature. When cross referencing occurred,
mainly from the psychology literature, the endowment effect was considered an exemplar of the
mere ownership effect (e.g., Reb & Connolly, 2007; Mandel, 2002).
The discussion regarding whether mere ownership effect or endowment effect is the
central broader phenomenon is out of the scope of the current investigation. While there seems to
be an overlap between the two, these can be also seen as theoretically distinct concepts. Both of
these effects may also be related to or affected by the status quo bias. In our view, the critical
point in distinguishing between the two concepts is regarding the impact of loss aversion, which
seems more prominent in the endowment effect. Most of the endowment effect research focuses
Mere ownership effect: Meta-analysis
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on trading and negotiations involving prices, clearly contrasting buying versus selling, thereby
emphasizing aspects related to potential gains or losses (e.g., Walasek, Matthews, & Rakow,
2015; Morewedge et al., 2009). Loss aversion is considered important in endowment effects yet
not essential for the mere ownership effect. For example, the ownership effect literature has
demonstrated the effect for immaterial targets. Nuttin (1985, 1987), in what is considered one of
the first demonstrations of the ownership effect, showed that people tend to like letters that
appear in their names more than letters that do not appear in their names. Clearly, there is no
prospect of "losing" a letter, and it is therefore implausible to perceive a threat of having to part
from it. It also suggests a broader definition and conceptualization of "ownership" than factual
legal ownership by an identifiable clear owner, as no one truly owns a letter of the alphabet, but
rather perceives an association between oneself and that immaterial object. Loss aversion,
therefore, cannot entirely account for the mere ownership effect and psychological ownership,
yet is considered a plausible explanation of the endowment effect with the embedded threat of
perceived loss.
We further discuss the similarities and differences between the two effects in the
discussion section below, with suggestions for future research to address the need to integrate the
two literatures and possibly disentangle the two phenomena.
Meta-analysis of Mere Ownership Effect
Aim
We embarked on a pre-registered meta-analysis aiming to examine the overall effects of
mere ownership on evaluation and liking of the target object, and to identify possible moderators.
We focused solely on experimental designs manipulating ownership as the independent variable,
contrasting conditions of ownership versus no-ownership over an object. The dependent
Mere ownership effect: Meta-analysis
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variables of interest were object valuations of pricing or liking. We expected to find support for
the phenomenon that people hold more favorable evaluations or higher liking towards owned,
relative to not-owned, objects.
Scope: Focusing on psychological ownership
We focused our meta-analysis exclusively on mere ownership effect, with the intention of
separating it from endowment effect. We limited the scope in the meta-analysis pre-registration
to studies that do not contrast buyers against sellers and/or WTP-WTA without explicitly
involving psychological ownership. In other words, we excluded studies that only implied
ownership by creating market transaction conditions. This way, we aimed to estimate the
magnitude of the mere ownership effect beyond market transactions and to address possible
confounds of psychological ownership with other processes, such as those related to trade and/or
loss aversion.
We also decided to exclude experiments involving paradigms based on the name-letter
effect (Nuttin, 1987), which demonstrated consequences of ownership on liking of name letters
which were conceptualized as owned immaterial objects. Over the years, the name letter effect
grew popular (e.g., Hoorens & Nuttin, 1993; Feys, 1995; Kitayama & Rarasawa, 1997) and has
been adopted as one of the most common measures of implicit self-esteem (Buhrmester, Blanton,
& Swann Jr, 2011; Hoorens, 2014). The name-letter paradigm has since been extended to other
factors that might be associated with the self, such as birthday date numbers (Kitayama &
Rarasawa, 1997; Nickell, Pederson, & Rossow, 2003). The idea of ownership in relation to
targets like names and birthdays was challenged and reformulated with the argument that letters
and date numbers are not truly chosen and are therefore not exclusively “owned” by a person.
These are different from other material objects that can be possessed and exclusively owned, or
Mere ownership effect: Meta-analysis
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from other immaterial objects such as articles and inventions that can be defined as persons'
unique intellectual property. Although an individual may associate name letters or birthday date
numbers with the self, it is unclear whether these associations at all entail psychological
ownership. We believe it is unlikely to find persons thinking of or referring to letters in their
names and numbers in their birthday dates as owned property. The name-letter effect includes
many other aspects not only related to ownership, if ownership is indeed reflected in this effect.
We therefore aimed to clearly differentiate between the two effects and excluded any articles of
the name-letter or similar effects.
Moderators of the mere ownership effect
We identified several factors in the literature that may affect the magnitude of the mere
ownership effect: duration of ownership, actual versus replica ownership, explicit versus implicit
ownership, loss aversion, mere exposure, factual/legal ownership, and material versus immaterial
object. All these processes were not assumed to explain the mere ownership entirely but have
been shown to impact the magnitude of the effect or even its existence. We review these
moderators below, discussing their theoretical significance and presenting some of the
supporting evidence. We provide a summary of the hypotheses in Table 1
We note that we embarked on this meta-analysis expecting a substantial number of
studies for each of the hypothesized moderators that would allow for conclusive evidence.
However, we were surprised by the small number of studies, resulting in underpowered analyses,
which should be regarded as suggestive rather than conclusive. We therefore recommend that
readers regard our moderators as theoretical directions for the mere ownership literature with
initial suggestive evidence. We return to this point in our discussion of the results.
Mere ownership effect: Meta-analysis
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Table 1
Hypotheses, findings in the literature, and meta-analysis findings
Hypotheses
Main findings in the literature
Meta-analysis
findings
Main hypothesis
Psychological ownership of an object
increases evaluation/liking of that
object.
Ownership increases the
evaluation/ liking of the object
(Beggan, 1992).
Supported
Moderator hypotheses
Loss potential:
1. The impact of ownership on
valuation/liking is different from null
(null not included in confidence
intervals) regardless of loss aversion.
2. The impact of ownership on
valuation/liking is stronger with
potential loss.
Mere ownership effect is not due
to loss aversion (Morewedge,
Shu, Gilbert, & Wilson, 2009).
Supported
Partially supported
Mere exposure:
1. Impact of ownership on
valuation/liking is different from null
(null not included in confidence
intervals) regardless of mere
exposure.
2. Impact of ownership on
valuation/liking is stronger with
same exposure than different
exposure.
Mere ownership effect occurs not
due to mere exposure (Beggan,
1992; Horrens & Nuttin, 1993).
Mere ownership effect is not
different between different
exposures (Horrens & Nuttin
1993; Beggan, 1992).
Supported
Not supported
Duration of ownership:
The impact of ownership on
valuation/liking is stronger in long
compared to short ownership
duration.
Longer duration of ownership can
enhance the mere ownership
effect (Strahilevitz &
Loewenstein, 1998; Peck & Shu,
2011).
Not supported.
Insufficient
variation in
experiments
Mere ownership effect: Meta-analysis
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Hypotheses
Main findings in the literature
Meta-analysis
findings
Actual vs. replica ownership:
Impact of ownership on
valuation/liking is stronger when
object is owned compared to when
the object is similar to an owned
object or a replica.
No experiments comparing
ownership on actual versus replica
ownership.
Supported
Material vs. immaterial objects:
1. Impact of ownership on
valuation/liking is stronger for
material objects (compared to
immaterial).
2. Impact of ownership on
valuation/liking is stronger for
immaterial objects.
No experiments comparing
ownership on material versus
immaterial objects1.
Not supported
Not supported
Factual versus implied ownership
Impact of ownership on
valuation/liking is stronger for
legally owned objects (compared to
no clear indication of legal
ownership).
Legal ownership strengthens
psychological ownership (Pierce,
Kostova, & Dirks, 2003)
Not supported
Explicit vs. implicit ownership:
The impact of ownership on
valuation/liking is stronger when
ownership is explicit compared to
implicit.
No experiments comparing
explicit versus implicit ownership.
Not supported
Potential for loss
Loss aversion has been used to explain the valuation of goods in market operations like
selling an owned object and the endowment effect, as we discussed in the introduction. Yet, the
1
A recent paper, published several years after the data have been collected for this project, compared ownership
effects in material to in immaterial objects, finding no differences between the two (Stefanczyk et al., 2021)
Mere ownership effect: Meta-analysis
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potential for loss may also affect ownership without involving trade. For example, losing a good
set of arguments when writing an argumentative essay could be perceived as a loss because it
may decrease chances to win the upcoming debate (De Dreu & van Knippenberg, 2005). Some
mere ownership experiments explicitly mention the possibility of parting with an owned object,
whereas some other do not. It is possible that the mentioning of potentially having to part with an
object activates some form of loss aversion, which in turn changes valuation. We therefore
sought to examine whether the mention of the possibility of not owning an object will moderate
mere ownership effects. This potential of loss is not to be confounded with loss aversion
resulting from deliberately trading (e.g., selling) an object.
We entertained two competing hypotheses regarding the moderating role of potential of
loss on mere ownership effect. Chatterjee, Irmak, and Rose (2013) found that when the object
was perceived as part of the self, parting from that object became threatening and led to stronger
mere ownership effect. Accordingly, we predicted that mere ownership effects would be stronger
when there was potential for loss compared to when there was no potential for loss. Yet, it is
possible that ownership alone is sufficient to induce positive evaluation or liking of the owned
object (Morewedge et al., 2009).
Mere exposure and duration of the ownership
Mere ownership effect may be driven by or associated with the mere exposure effect: the
phenomenon that mere repeated exposure to an object, regardless of its ownership status,
enhances favorable evaluations of the object (Zajonc, 1968). Repeated exposure to an object
increases the ease by which information is processed (perceptual fluency), which in turn
increases positive affect (Bornstein & D’Agostino, 1994). Since ownership often involves more
exposure to the owned object, it is unclear whether or to what extent mere ownership effect is
Mere ownership effect: Meta-analysis
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accounted by mere exposure (Beggan, 1992). If mere exposure affects ownership, it would be
expected that more exposure (i.e., over longer period of time) would increase the strength of the
mere ownership effect.
There have been mixed views regarding whether the duration of ownership is a factor in
the mere ownership effect. On the one hand, Strahilevitz and Loewenstein (1998) suggested that
people tend to value an object more immediately after owning it, though they argued it may take
some time for a full sense of ownership to develop and reach maximal impact. They
demonstrated that favorable evaluations of an owned object increased the longer the ownership
lasted, and this has been successfully replicated in subsequent studies (e.g., Shu & Peck, 2011).
On the other hand, some studies found that mere ownership effects occur even before the
ownership has been clearly defined (Peck & Shu, 2009).
The duration of ownership varies across existing studies. In some studies, participants
rated an object given to them in the experiment (e.g., Beggan, 1992), whereas in other studies,
participants evaluated an object that has been owned for a long period of time (e.g., Nesselroade,
Beggan, & Allison, 1999). It is therefore unclear whether the duration of exposure critically
contributes to the mere ownership effect, amplifies it, or is simply an unrelated factor. We
predicted that the duration of ownership is positively related to mere ownership effects, such that
the mere ownership effects would be stronger the longer the duration of ownership.
Mere ownership effect: Meta-analysis
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Actual versus replica ownership
Would a simulation of ownership have the same effect as actual ownership? In actual
ownership, the evaluated object is owned by the individual, whereas in replica ownership, the
evaluated object is a replica - an object similar to the one owned. Past research suggested that
replicas may trigger weaker mere ownership effects than actual objects did. For example, Barone
et al. (1997) conducted a replication of Beggan’s studies (1992), observing much smaller effect
size compared to that of original experiments. Later, Beggan and Allison (1997) conducted a
mini meta-analysis of their studies and concluded that Barone et al. (1997) manipulated
ownership by asking participants to evaluate a replica, which appeared to be a crucial departure
from Beggan’s (1992) manipulation in which the actual owned object was used. Beggan and
Allison (1997) argued that the weakened effects could perhaps be explained by participants’
weaker or lacking attachment to the replica, compared to an object that is factually owned. Thus,
we predicted that mere ownership effects would be stronger when the target object is owned
compared to when the target object is a replica.
Material versus immaterial object
Does ownership have the same effects for material and immaterial objects? The mere
ownership effect has been demonstrated on both material objects such as insulators and mugs
(e.g., Barone et al., 1997; Morewedge et al., 2009), and immaterial objects, such as arguments
(De Dreu & van Knippenberg, 2005), letters (Nuttin, 1987), symbols (Feys, 1991), and time
(Hoorens, Remmers, & van de Riet, 1999). We therefore explored the moderating effect of
material versus immaterial objects.
Mere ownership effect: Meta-analysis
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Factual versus implied ownership
Factual ownership, in contrast to implied ownership, requires the presence of actual
ownership. Ownership can be induced by offering an object to participants or by a clear
declaration that ownership has taken place (Barone, Shimp, & Sprott, 1997; Beggan, 1992;
Morewedge, Shu, Gilbert, & Wilson). In these cases, the possession is considered factual, and
the person is then considered the clear owner, with legal implications. In contrast, ownership can
also be implied or inferred indirectly. Implied ownership is a feeling of ownership to objects that
are not factually owned. For example, in a simulated police investigation self-collected clues
were perceived as more informative than objectively equally informative clues collected by
colleagues (Toma, Bry, & Butera, 2013). Similarly, individuals who had the opportunity to touch
an object perceived an object as subjectively “more owned” and also as worth more (Peck &
Shu, 2009). Because the touched object was explicitly offered to be sold to participants, mere
opportunity to touch it had no impact on its real ownership status.
It seems that both factual and implied ownership can induce mere ownership effects, yet
factual ownership may induce stronger sense of ownership than implied ownership. Therefore,
we predicted that the mere ownership effects would be stronger when the ownership is factual
relative to implied.
Explicit versus implicit mentioning of ownership
Some experimental evidence suggests that the mere ownership effect can be caused
merely by an indirect suggestion that an item is owned. Such effect is however weaker compared
to stronger effects if the ownership is made explicit. This is likely connected to the strength of
the stimuli intended to drive a response, with subtle cures being less likely to trigger
corresponding behavior or more likely to trigger weaker responses compared to more salient
Mere ownership effect: Meta-analysis
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cues (Carpenter, 2009). To illustrate, in the seminal Beggan (1992) experiment, participants were
explicitly instructed that once the study concludes the evaluated item will be theirs. In contrast,
Peck and Shu (2009) asked participants to touch an object, this way allowing participants to
assume some sort of ownership. Similarly to Peck and Shu (2009), Toma et al., (2013) invited
participants to a simulated investigation and provided them with unique sets of clues that only all
combined produced the correct solution. Despite the fact that the ownership over the clues was
never made explicit, participants still found their clues more important compared to other’s
clues.
This explicit vs implicit mentioning of ownership should not be confounded with legal
status of the ownership, because the former only refers to how the ownership status of an object
has been communicated to participants. Implicit ownership in which ownership is not clearly
stated is weaker than explicit ownership which is clearly defined. We expected weaker mere
ownership effects in implicit compared to explicit ownership studies.
Exploratory methodological moderators
We examined additional moderators regarding methods. We explored whether particular
choices regarding the design of experiments could affect the observed strength of the mere
ownership effect.
Between-subject versus within-subject experimental design
When evaluating several items in within-subject designs, people tend to make
comparisons and use cues to try and differentiate among these objects. Comparisons are not
possible in between-subject designs, and the same cues may seem less important and therefore
have less impact on evaluations. For example, the color of a car may not seem to be a critical
feature when considering purchasing one specific car, yet color may become the defining factor
Mere ownership effect: Meta-analysis
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when the decision involves a comparison of two or more mostly similar cars that differ mainly
on color.
Demand effects may be stronger in within-subject design (Zizzo, 2010). Participants in
within-subject designs may infer the experimental design by making comparisons, and adjust
their responses according to what they think the experiment is meant to test. For example,
willingness to pay for a sandwich at the airport will be much larger in within-subject condition
(e.g., when such sandwich will be explicitly contrasted with a sandwich in a regular store),
compared to in between-subject design (e.g., when half of participants would estimate their
willingness to pay for a sandwich at the airport, and the other half in a regular store) (Charness,
Gneezy, & Kuhn, 2012). We predicted that mere ownership effects will be stronger in within-
subject designs.
Dependent variable: Liking versus pricing
Preference for an object can be expressed in many ways. Two broad categories used in
mere ownership research are liking evaluations of an object (i.e., how good an object is) and
object pricing (i.e., how much an object is worth). These measures are sensitive to different
external cues. For example, in one study people liked organic beef over conventional beef, and
wanted to pay more for it, but products’ pricing did not correlate with liking (Napolitano et al.,
2010). Possibly, the individuals who wanted to pay more for the organic beef were different
individuals who liked the organic beef more, which suggests that these two processes of liking
and pricing could be psychologically distinct. Other research suggests that contextual cues
(pricing of similar products) affect pricing but less so for the liking of a target product (Adval &
Monroe, 2002). Moreover, pricing has objective anchors (i.e., market price of a similar object)
whereas liking is purely subjective, and therefore might be more malleable (Chapman &
Mere ownership effect: Meta-analysis
20
Johnson, 2002). Finally, it has been suggested that liking is encoded in a different brain region
than pricing (Kodaverdian, 2019).
All the above research suggests pricing and liking can tap into different psychological
processes. We therefore expected stronger mere ownership effect in liking compared to pricing.
Method
Pre-registration and protocol
We pre-registered our meta-analysis plan including coding and data analysis procedures
on the Open Science Framework (https://osf.io/txnsk). Materials used in this meta-analysis and
disclosures are provided in the supplementary. Data, code, and materials were shared on the
Open Science Framework (https://osf.io/fdyqw/).
Literature search and selection of studies
Search, coding, and data collection ended in 2018 and the meta-analysis covers the
literature up until that point. We searched Google Scholar for ownership related keywords and
articles that cited or were related to Beggan (1992) (See Supplementary Materials for details)
2
. A
total of 765 articles were identified. After reading their abstracts, we identified 93 relevant
articles and reviewed each of these papers to evaluate adherence to inclusion and exclusion
criteria. We only included experiments that explicitly manipulated psychological or perceived
ownership (e.g., owner versus non-owner), and assessed evaluations, rankings, or liking of target
objects as the dependent variables. We contacted all authors of identified publications, contacted
researchers on mailing lists, issued call for unpublished papers on social media, and posted
preprints of our work eliciting feedback and studies. However, despite our efforts we were
2
We relied uniquely of the Google Scholar database, since it is a most comprehensive database, including also
preprints and working papers. Recent work suggests such query is suitable for conducting meta-analyses (Gehanno,
et al., 2013; Martín-Martín, et al., 2018; Walters, 2007).
Mere ownership effect: Meta-analysis
21
unsuccessful in finding unpublished manuscripts beyond the ones we identified through our
search process.
Our goal was to test the mere ownership effect, and to disentangle the effect from the
buyer-seller paradigm, in which the increase in pricing or evaluations of an owned object could
be attributed to strategic choices and the possibility of participants assuming their task was to
negotiate as much as possible for what they are expected to sell (Plott & Zeiler, 2005). To focus
our efforts solely on the mere ownership phenomenon, we formulated the following exclusion
criteria: (1) perceived ownership was only mentioned but not directly measured, (2) owners and
sellers were treated interchangeably, (3) studies involving a transaction of an owned or non-
owned object, (4) studies on loss aversion and name letter/birthday number effects (which later
developed into a prolific area of inquiry regarding implicit self-esteem), (5) experiments with
ownership as the dependent variable, or with indirect dependent variables such as accuracy of
recall, memory, reaction time, or implicit indirect evaluations, and (6) reported data were
insufficient to calculate effect sizes.
Mere ownership effect: Meta-analysis
22
Table 2
Samples included in the meta-analysis
Study and sample
DV type
N
Ownership
duration
Actual (vs.
replica)
ownership
Explicit (vs.
Implicit)
ownership
Loss aversion
Mere
exposure
Material (vs.
immaterial)
object
Research
Design
Factual
ownership
1
Barone, Shimp, &
Sprott (1997) S1
Evaluation
149
Immediate
/recent
Replica
Explicit
No potential
loss
Same
exposure
Material
Within-
subjects
Factual
ownership
2
Barone, Shimp, &
Sprott (1997) S2
Evaluation
43
Immediate
/recent
N/A
Explicit
No potential
loss
Same
exposure
Material
Between-
subjects
Factual
ownership
3
Barone, Shimp, &
Sprott (1997) S3
Evaluation
94
Immediate
/recent
Actual
Explicit
No potential
loss
Same
exposure
Material
Between-
subjects
Factual
ownership
4
Barone, Shimp, &
Sprott (1997) S4
Evaluation
92
Immediate
/recent
N/A
Explicit
No potential
loss
Same
exposure
Material
Between-
subjects
Factual
ownership
5
Beggan (1992) S1
Evaluation
41
Immediate
/recent
N/A
Explicit
No potential
loss
Same
exposure
Material
Within-
subjects
Factual
ownership
6
Beggan (1992) S2
Evaluation
57
Immediate
/recent
N/A
Explicit
No potential
loss
Same
exposure
Material
Within-
subjects
Factual
ownership
7
De Dreu & van
Knippenberg
(2005) S1
Price
95
Immediate
/recent
Actual
Explicit
Potential loss
Same
exposure
Immaterial
Between-
subjects
Factual
ownership
8
De Dreu & van
Knippenberg
(2005) S2
Price
299
Immediate
/recent
Actual
Explicit
Potential loss
Same
exposure
Immaterial
Between-
subjects
Factual
ownership
Mere ownership effect: Meta-analysis
23
Study and sample
DV type
N
Ownership
duration
Actual (vs.
replica)
ownership
Explicit (vs.
Implicit)
ownership
Loss aversion
Mere
exposure
Material (vs.
immaterial)
object
Research
Design
Factual
ownership
9
De Dreu & van
Knippenberg
(2005) S3
Price
44
Immediate
/recent
Actual
Explicit
Potential loss
Same
exposure
Immaterial
Between-
subjects
Factual
ownership
10
De Dreu & van
Knippenberg
(2005) S4
Price
82
Immediate
/recent
Actual
Explicit
Potential loss
Same
exposure
Immaterial
Between-
subjects
Factual
ownership
11
Feys (1991) S1
Evaluation
82
Immediate
/recent
N/A
Explicit
No potential
loss
Same
exposure
Immaterial
Within-
subjects
No
factual
ownership
12
Morewedge, Shu,
Gilbert & Wilson
(2009) S1
Price
45
Immediate
/recent
Actual
Explicit
Potential loss
vs. No
potential loss
Different
exposure
Material
Between-
subjects
Factual
ownership
13
Morewedge, Shu,
Gilbert & Wilson
(2009) S2
Price
78
Immediate
/recent
Actual
Explicit
No potential
loss
Different
exposure
Material
Between-
subjects
Factual
ownership
14
Nesselroade,
Beggan, & Allison
(1999) S3
Evaluation
22
Immediate
/recent
Actual
Explicit
No potential
loss
Same
exposure
Material
Between-
subjects
Factual
ownership
15
Nikander,
Liikkanen &
Laakso (2014) S1
Evaluation
18
Immediate
/recent
Actual
Explicit
No potential
loss
N/A
Immaterial
Between-
subjects
No
factual
ownership
16
Peck & Shu
(2009) S1
Price
231
Immediate
/recent
Actual
Implicit
No potential
loss
Same
exposure
Material
Between-
subjects
No
factual
ownership
17
Peck & Shu
(2009) S3
Price
401
Immediate
/recent
Actual
Explicit
Potential loss
N/A
Material
Between-
subjects
Factual
ownership
18
Peck & Shu
(2009) S4
Price
334
Immediate
/recent
Actual
Explicit
Potential loss
Same
exposure
Material
Between-
subjects
Factual
ownership
Mere ownership effect: Meta-analysis
24
Study and sample
DV type
N
Ownership
duration
Actual (vs.
replica)
ownership
Explicit (vs.
Implicit)
ownership
Loss aversion
Mere
exposure
Material (vs.
immaterial)
object
Research
Design
Factual
ownership
19
Sen & Johnson
(1997) S1
Evaluation
& Price
36
Immediate
/recent
Replica
Explicit
No potential
loss
Same
exposure
Material
Within-
subjects
Factual
ownership
20
Sen & Johnson
(1997) S2
Evaluation
& Price
96
Immediate
/recent
Replica
Explicit
No potential
loss
Same
exposure
Material
Within-
subjects
Factual
ownership
21
Shu & Peck
(2011) S1
Price
67
Immediate
/recent
Actual
Explicit
Potential loss
Same
exposure
Material
Between-
subjects
Factual
ownership
22
Strahilevitz &
Loewenstein
(1998) S1
Price
85
Immediate
/recent
Actual
Explicit
Potential loss
Same
exposure
Material
Between-
subjects
Factual
ownership
23
Toma, Bry &
Butera (2013) S1
Evaluation
50
Immediate
/recent
Actual
Implicit
No potential
loss
Same
exposure
Immaterial
Within-
subjects
No
factual
ownership
24
Walasek, Rakow,
& Matthews
(2017) S1
Evaluation
& Price
168
Immediate
/recent
Actual
Explicit
Potential loss
Same
exposure
Material
Between-
subjects
Factual
ownership
25
Walasek, Rakow,
& Matthews
(2017) S2
Price
175
Immediate
/recent
Actual
Explicit
Potential loss
Same
exposure
Material
Between-
subjects
Factual
ownership
26
Walasek, Rakow,
& Matthews
(2017) S3
Price
140
Immediate
/recent
Actual
Explicit
Potential loss
Same
exposure
Material
Between-
subjects
Factual
ownership
Note. S = Study number. N/A = information not available in the original studies.
Mere ownership effect: Meta-analysis
25
Figure 1
Meta-analysis PRISMA flow diagram
Mere ownership effect: Meta-analysis
26
In the final sample we included a total of 26 unique samples from 13 articles (N = 3024)
(see Table 2 for a summary of the selected experiments and the variables in each of the
experiments). All but one samples were university students, and all of the samples were from
Western countries (e.g., the U.S., UK, Netherlands, Finland, etc.)
3
. The PRISMA diagram in
Figure 1 illustrates the four stages of study search and inclusion.
Coding
We pre-registered a coding worksheet. In a pilot test, two authors coded five studies and
refined coding in two rounds, reaching a consensus on coding scheme and procedure. Authors
then divided their role in coding the rest of studies. One junior author extracted relevant
information from articles about the ownership manipulation, dependent variables, reported
statistics used to calculate effect sizes, and moderators. Each row in the coding sheet recorded
one comparison between ownership versus non-ownership. If the original experiment examined
moderating factors other than ownership, then the information for ownership for each of the
moderator levels was recorded in separate rows. A second more senior author then verified the
extracted data and information, and made adjustments if necessary. A third author later verified
the coding and analyses.
We coded effect sizes when those were reported. In cases where effect sizes were not
reported, we used descriptive statistics (i.e., mean, standard deviation), and resulted to inferential
statistics (i.e., F values, t values, degrees of freedom) when those were not available. Eventually,
all effect sizes were converted to Hedge's g. All the conversions and coding decisions were
documented in the coding sheet to ensure reproducibility.
3
Almost all collected samples were from the USA (62%), Netherlands (15%), and the UK (12%), and all but one
studies tested students (96%). A question arises about generalizability of our findings beyond the overrepresented in
this metaanalysis western samples. Given the lack of diversity, we are unable to statistically test for this issue, but
encourage researchers to test other populations for the mere ownership effect.
Mere ownership effect: Meta-analysis
27
Analyses
We used the Metafor package in R (Viechtbauer, 2010) for data analyses. Taking into
account the variations induced by potential moderators and different research designs (i.e.,
between-subjects versus within-subjects), we applied a random-effects with maximum likelihood
model. First, we examined the overall effect size of mere ownership across studies. We also
tested for the heterogeneity the extent to which variation in the effect sizes was accounted by
differences in true effects or by sampling error with a Cochran’s Q test and the I2 statistic
(Higgins, Thompson, Deeks, & Altman, 2003). Second, we examined the possibility of a
publication bias in the overall mere ownership effects. Third, we tested the effects of the
proposed moderators.
Results
We summarized the findings in Table 3 and indicated whether we found support for the
meta hypotheses in Table 1. Forest and funnel plots of the included samples are presented in
Figure 2 and Figure 3.
Mere ownership effect: Meta-analysis
28
Table 3
Summary of effect sizes for main and moderator analyses
Analyses
Hedge’s g
SE
p
95% CI
Lower
95% CI
Upper
k
Main analysis
0.55
0.06
< .001
0.43
0.66
26
Actual ownership
0.66
0.07
< .001
0.53
0.78
18
Replica ownership
0.29
0.15
= .060
0.01
0.58
3
Legal/factual ownership
0.54
0.06
< .001
0.41
0.6
22
No legal/factual ownership
0.60
0.13
< .001
0.35
0.84
4
Potential loss
0.69
0.08
< .001
0.54
0.84
12
No potential loss
0.43
0.07
< .001
0.30
0.57
15
Same exposure
0.51
0.06
< .001
0.39
0.64
22
Different exposure
0.74
0.19
< .001
0.36
1.11
2
Material object
0.48
0.07
< .001
0.35
0.61
19
Immaterial object
0.73
0.10
< .001
0.54
0.92
7
Between-subjects design
0.61
0.07
< .001
0.48
0.73
19
Within-subjects design
0.41
0.10
< .001
0.22
0.61
7
Evaluation
0.40
0.07
< .001
0.25
0.54
13
Price
0.63
0.06
< .001
0.51
0.75
16
Implicit
0.64
0.28
= .0213
0.10
1.18
2
Explicit
0.54
0.06
< .001
0.42
0.66
24
Mere ownership effect: Meta-analysis
29
Overall mere ownership effect
We first examined the overall effect of mere ownership on evaluation/liking. The mean
effect size was positive and significantly different from null (k = 26, g = 0.55 [0.43, 0.66]). This
suggests that across the selected studies, participants had more positive evaluations or more
liking towards owned objects relative to not-owned objects. We provided evidence for the
existence of the mere ownership effect to be larger than zero, yet we caution in considering
meta-analysis as definite (Kvarven, Strømland, & Johannesson, 2019).
Publication bias
We summarized publication bias analyses in Table 4. Publication bias findings were not
conclusive, yet they were suggestive of a possible publication bias in favor of the effect, possibly
leading to an over-estimation of the effect. Still, even with corrections for publication bias the
mere ownership effect was found meaningfully different than the null.
For example, using the three-parameter selection model, considered by recent reviews to
be the best performing bias correction method (Carter, Schönbrodt, Gervais, & Hilgard, 2018),
the mere ownership effect was g = 0.40 [0.19, 0.62], with comparable effects for other correction
methods (Puniform: g = 0.54 [0.44, 0.67]; Henmi & Copas: g = 0.44 [0.28, 0.61]; trim and fill: g
= 0.46 [0.33, 0.58]). Therefore, regardless of the publication bias analyses and the correction
employed, all models indicated a weak to medium effect size (g > 0.32, except for PET) with
confidence intervals that do not include the null.
Mere ownership effect: Meta-analysis
30
Figure 2
Forest plot of effect sizes for studies included in the meta-analysis.
Mere ownership effect: Meta-analysis
31
Figure 3
Funnel plot with Trim and Fill
Note. Funnel created using metaviz R package (Kossmeier et al., 2019). White dots indicate
included studies, black dots added by trim and fill simulation for missing studies, with dotted
line indicating adjusted meta-analytic estimate given the trim and fill adjustment. Red line
indicated Egger's regression line.
Mere ownership effect: Meta-analysis
32
Table 4
Publication bias analyses
Publication bias analysis method
Results and adjusted models
Three-parameter selection model
Likelihood Ratio Test: χ2(1) = 5.33, p = 0.02
Adjusted Model: g = 0.40 [0.19, 0.62]
PET
b = 0.08 [-0.16, 0.33], p = .476
PEESE
b = 0.32 [0.17, 0.47], p < .001
Puniform
Adjusted Model: g = 0.54 [0.44, 0.67],
22 significant
Henmi & Copas (2010)
Adjusted Model: g = 0.44 [0.28, 0.61]
Trim and fill funnel plot asymmetry
6 studies missing on the left side.
Adjusted model: g = 0.46 [0.33, 0.58])
(see Figure 3)
Rank correlation test
(Begg & Mazumdar, 1994)
Kendall's tau = 0.16, p = .255
Egger's regression test
z = 2.54, p = 0.011
Note. Values in parentheses indicate 95% confidence intervals [lower bound, upper bound]
Mere ownership effect: Meta-analysis
33
Moderator analyses
We first conducted a Cochran’s Q test and found significant heterogeneity between effect
sizes across studies (Q = 105.80; I2 = 70.9%; p < .001), indicative of moderate to high variance
(Higgins et al., 2003). We therefore proceeded with the planned moderator analyses.
We coded theoretical and methodological moderators according to a pre-registered
criteria and coding sheet: Duration of ownership, use of replica, implicit versus explicit
ownership, factual vs imagined ownership, potential loss of ownership, mere exposure, object
materiality, research design between-within subject; and type of the DV: liking vs price. The
duration of ownership moderator had no variance in the coded experiments, thereby resulting in
eight moderators.
When planning the meta-analysis, we expected a larger set of samples. Yet, the small
studies sample size that met our pre-registration inclusion/exclusion criteria resulted in low
power and limited our ability to conduct robust moderator analyses using a traditional meta-
regression. To allow for moderator analyses and address the power issue without risking
overfitting, we employed metaforest (Curry et al., 2018; Van Lissa, 2017), which uses a machine
learning algorithm "random forests" and bootstrapping to assess several potential moderators.
This is an unexpected extension which we did not include in the pre-registration data analysis
plan. The full results and detailed plots are provided in the supplementary. The main indicator of
R squared (R-OOB) was 0.26, indicating that moderators predicted variance in the effect (I2:
74.7%; Q: 178.74, p < .001), with the valuing type, use of replica, and object materiality showing
the highest variable/permutation importance, followed by weaker importance for loss aversion
and legal/factual ownership, and close to no effect for mere exposure and implicit versus explicit
ownership (see Supplementary Materials for details).
Mere ownership effect: Meta-analysis
34
We aimed to supplement the metaforest moderator findings by conducting a z-test
moderation analysis of the effects for the identified important moderators. The effects of the
moderators per each coded category are reported in Table 3 and their z-test and multi-level
regression analyses (using a single moderator) are detailed in Table 5. Use of replica, loss
aversion, and valuing type had the strongest effect with both z-test and multi-variate multi-level
effects p < .05.
Based on both analyses combined we conclude valuing type, potential of loss, and use of
replica as strongest moderators of the mere ownership effect.
Table 5
Comparisons for all moderators
Moderators
Diff
SE
z
p
95% CI
Lower
95% CI
Upper
k
MV
ML p
Actual vs. replica ownership
-0.37
0.17
-2.47
.025
-0.70
-0.05
21
.011
Legal vs. no clear legal ownership
0.06
0.14
0.41
.680
-0.22
0.33
26
.794
Potential loss vs. no potential loss
0.43
0.10
2.49
.013
0.05
0.46
27
.009
Same vs. different exposure
-0.21
0.21
-0.97
.328
-0.62
0.21
24
.311
Material vs. immaterial object
-0.25
0.12
-2.14
.032
-0.48
-0.02
26
.064
Between vs. within design
-0.19
0.12
-1.58
.114
-0.43
0.05
26
.080
DV category: Evaluation vs. price
0.24
0.10
2.47
.013
0.05
0.42
29
.018
Implicit vs. explicit
0.10
0.28
0.35
.724
-0.46
0.66
26
.673
Note. Bolded moderators were found to be significant on the mere ownership effects, with 95%
confidence intervals not including zero. Number of studies in comparison may be higher than
overall number of samples included in the meta-analysis (26) due to some studies manipulating a
factor (e.g., loss) or including more than one factor (e.g., evaluation vs. price). MV ML p = p-
value for multi-variate meta-analysis multi-level moderator analysis.
Mere ownership effect: Meta-analysis
35
Discussion
Mere ownership effect: Main findings
We conducted a meta-analysis of mere ownership effect and our findings revealed
consistent support for the phenomenon, with psychological ownership leading to higher
valuations of an object. We found some indications yet no conclusive evidence for publication
bias. We applied corrections for publication bias and found that even using most methods the
mere ownership effect was different from the null with most indicating a moderate effect (with
the exception of PET). Our findings suggest that the mere ownership effect is fairly robust, with
positive medium to large effects across all subgroups of the studied moderators (see Table 3) and
publication bias corrections.
Moderators
We found moderate to high variance in the meta-analytic effects, and we theorized and
tested several potential moderators. We summarized our conclusions regarding the moderator
hypotheses in Table 1. Given the limited number of studies, and relatively small sample sizes in
them, the evidence supporting any of the moderators is rather weak, and should be considered
only as a signpost for future studies. We found that the mere ownership effects were stronger in
studies where: (1) evaluations were given on the target objects rather compared to on a replica,
(2) measurement was of price compared to liking. There were some indications for partial
support for loss aversion, yet we summarize weaker support and mixed findings across the
different methods for the other moderators.
Similarities in Endowment and Ownership effects
We note similarities between the mere ownership and endowment effects. In their review
paper, Morewedge and Giblin (2015) mentioned that the endowment effect is not limited to
Mere ownership effect: Meta-analysis
36
material objects and has also been shown to apply to “entitlements such as time, intellectual
property, public land, and environmental, health, and safety regulations” (p. 339). Similarly,
mere ownership affects immaterial objects such as set of arguments to be used in a discussion
(De Dreu & van Knippenberg, 2005), or self-generated design concepts (Nikander, Liikkanen &
Laakso, 2014). The endowment effect has been observed in goods to be acquired as much as in
actually owned goods (Ericson & Fuster, 2014). Similar effects have been observed for mere
ownership, as factual ownership was not required for the effect to occur and implied ownership
was enough to affect valuations (Nikander, Liikkanen & Laakso, 2014; Peck & Shu, 2009).
Finally, research on children has shown that children display both the endowment effect
(Harabaugh, Krause, & Vesterlund, 2001; Hood et al., 2016) and the mere ownership effect
(Hood & Bloom, 2008; Hartley & Fisher, 2018), suggestive of an innate characteristic of both
effects. These similarities are the reason why the two concepts are sometimes treated
interchangeably.
Disentangling the Ownership-Endowment Confounds
We organized differences between the endowment and the mere ownership effects into
two groups: theoretical and methodological. From the theoretical perspective, mere ownership
may involve psychological and other factors that are not related to trading or endowment effect,
and endowment effect phenomenon may involve factors that go beyond or are unrelated to
ownership (e.g., recalling different reference prices, or misperception of the experiment as a
bargain exhibit; Morewedge & Giblin, 2015). Related evidence comes from Reb and Connolly
(2007). In their experiment, people who possessed a chocolate bar valued it more, but this effect
was fully mediated by perceived ownership. Specifically, those who possessed a bar felt greater
ownership, which in turn predicted higher valuations of the bar. According to their findings,
Mere ownership effect: Meta-analysis
37
valuation effects of possession can be fully explained by psychological ownership and the mere
ownership effect. This is but just one experimental finding contributing to an ongoing debate on
this topic.
From the methodological perspective, a major difference is that the endowment effect is
mostly studied using pricing of owned objects, whereas the mere ownership effect is often
investigated with liking or other subjective measures of preference. Next, the buyer-seller
paradigm used in endowment effect research conflates ownership with expected transfer of
ownership eliciting loss-gain related effects such as loss aversion (Chatterjee, Irmak, & Rose,
2013). Experimental evidence supporting the loss aversion explanation of endowment effect has
been mixed. It has been supported by some studies (e.g., Carmon & Ariely, 2000; Johnson,
Häubl, & Keinan, 2007; Kahneman, Knetsch, & Thaler, 1990), whereas other studies
demonstrated that it was not loss aversion but perceived ownership associations that induced
mere ownership effects (e.g., Maddux et al., 2010; Morewedge et al., 2009; Peck & Shu, 2009).
Hence, perceived ownership can be used to explain the endowment effect, and loss aversion
could be seen as a factor that further amplifies this effect. Alternatively, loss aversion requires
feelings of ownership to even occur, and thus cases where ownership is weak produce little to no
loss aversion, and cases where ownership is strong produce significant loss aversion.
Mere ownership and endowment effects
How does mere ownership effect relate to endowment effect? Above, we discussed
similarities and differences between the two effects. This meta-analysis cannot and was not
meant to resolve this debate or provide evidence to support one account over the other. Yet, in
our meta-analysis we attempted to zero in on mere ownership effects that do not involve
Mere ownership effect: Meta-analysis
38
endowment by excluding studies that conflated buying versus selling and WTA-WTP paradigms
with ownership.
We briefly address this debate by reviewing several perspectives on the conceptualization
and link between the mere ownership effect and the endowment effect below, with three models
summarized in Figure 4. In this diagram, large boxes correspond to broader concepts, and
smaller boxes to narrower concepts. When one concept is encompassed within the other in a box
then this it meant to suggest that the boxed concept is a narrower instantiation of the
encompassing concept. The arrow below each box represents the magnitude of the loss aversion
involved in a particular process, and the endowment effect appears to the right than the mere
ownership effect. One view, depicted in Panel A, suggests that the endowment effect is broader,
as it encompasses several factors including psychological ownership (Morewedge & Giblin,
2015). Another view, depicted in panel B, suggests that the mere ownership effect is broader,
with the endowment effect being the narrower trade-related exemplification (Beggan, 1992;
Mandel, 2002; Ziano et al, 2020).
Mere ownership effect: Meta-analysis
39
Figure 4
Three views on the conceptualization of mere ownership effect and endowment effect
We reviewed similarities between endowment and mere ownership effects. The mere
ownership and the endowment effects seem to affect both material and immaterial objects. The
two effects also do not require factual ownership, but a mere implication of ownership suffices
for the effects to occur. The endowment effect is typically demonstrated using pricing valuations.
Our findings demonstrated that ownership affected both pricing and evaluations, with slightly
stronger effects for pricing. Future research may examine the interplay of these two types of
dependent variables and how both are affected under the endowment and mere ownership
paradigms.
Considering the similarities between the two concepts, we introduce a third perspective
which suggests that the mere ownership effect and the endowment effect may be instantiations of
the same psychological process differing in the degree of loss aversion (Figure 4, panel C). In
that model, both effects are on two ends of the same continuum, from weaker loss aversion for
the mere ownership effect to stronger loss aversion for the endowment effect (Gawronski,
Mere ownership effect: Meta-analysis
40
Bodenhausen, & Becker, 2007; Hoorens, Remmers, & Van De Riet, 1999; Morewedge et al.,
2009). Both effects can be thought of as differently operationalized and investigated
instantiations of the same psychological process.
This meta-analysis cannot help and decide between the three accounts. Instead, we
propose a framework to unify them. We call on future research to try and further elucidate these
links and possibly disentangle mere ownership from endowment effect to test the three suggested
accounts.
Limitations and future directions
Our meta-analysis reflects a problem in the field of the mere ownership research, that is,
scarcity of direct experimental evidence. After exclusion of potential confounding research such
as name-letter research and tasks involving trading, we were left with only 13 papers with 26
experiments. A streamline effect of this scarcity of research is that some of our moderator
analyses included samples as small as n = 2 for difference in exposure to the object, and for
implicit vs. explicit mentioning of ownership, n = 3 for replica ownership, and n = 4 for legal vs.
no legal ownership. Moreover, all analyzed experiments have relatively weak power, with total
number of subjects’ N = 3024 which averages to about n = 120 per experiment. Such sample size
merely allows the detection of relatively large effects of d = 0.51.
We aimed to deal with this issue by employing a dedicated machine learning algorithm
(random forest) and increasing the analyzed sample size by repeated sampling with replacement
of the available data (bootstrapping). Although these methods perform quite well in simulations,
they can never replace real data. We therefore call on scientists interested in mere ownership or
endowment effect to further test these effects, especially in the context of potential moderators
and using other samples (more on that below). Replica (vs. original) and valuing type seem to be
Mere ownership effect: Meta-analysis
41
the most likely to return meaningful results for moderation effects that have never been directly
tested. We also call scientists to try to disentangle mere ownership from the endowment effect.
The experiments included in the meta-analysis were conducted in the USA and in the
European Union countries. All but one experiments tested graduate or undergraduate students.
We were surprised by the small number of studies conducted on this important phenomenon, and
this is one of the largest challenges with the existing data: limiting our ability to generalize
findings (Henrich et al., 2010). Therefore, more work is required to assess the robustness of the
mere ownership bias in other samples, and in different cultures. Moreover, many of the studies,
despite being flagship papers at the time of their publication, seem to suffer from low power and
small samples. Many of the included studies were meant as a demonstration of the effect yet
provide us with limited information about the magnitude of the effect. For example, the seminal
work by Beggan (1992) estimated the effect size from an almost negligible g = 0.07 to
implausibly large g = 1.32. To better illustrate this range, if studies would compare IQ score
across groups, these effect sizes would mean a difference in scores ranging from about 1 point to
almost 20 points. This has critical implications for practitioners, considering how much of an
impact ownership can have on evaluations and pricing of objects.
Conclusion
We conducted a meta-analysis and found support for mere ownership effect with an
overall medium effect size and with replica use, potential of loss, and valuing type moderating
the effect. Our findings indicated that mere ownership effect may occur regardless of related
phenomena of endowment effect and loss aversion and our moderator analyses suggested
directions for exploring boundary conditions. We call for much more future research into this
Mere ownership effect: Meta-analysis
42
phenomenon, and research aimed at disentangling and linking the mere ownership and
endowment effects.
Open Practices Statement
We pre-registered our meta-analysis plan including coding and data analysis procedures on the
Open Science Framework (https://osf.io/txnsk). Study was pre-registered prior to conducting the
research. Materials used in this meta-analysis and disclosures are provided in the supplementary.
Data, code, and materials were shared on the Open Science Framework (https://osf.io/fdyqw/).
Data collection was completed before conducting an analysis of the data. All variables collected
for this meta-analysis are reported and included in the provided data.
Mere ownership effect: Meta-analysis
43
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Mere ownership effect meta-analysis: Supplementary 1
Owning leads to valuing:
Meta-analysis of the Mere Ownership Effect
Supplementary Materials
Contents
Open Science ......................................................................................................................... 3
Disclosures ............................................................................................................................ 3
Data collection ................................................................................................................... 3
Variables reporting ............................................................................................................ 3
Planned moderators ............................................................................................................... 4
Duration of ownership ....................................................................................................... 4
Actual versus replica ownership......................................................................................... 4
Explicit versus implicit ownership ..................................................................................... 4
Loss aversion ..................................................................................................................... 4
Mere exposure ................................................................................................................... 5
Material versus immaterial object ...................................................................................... 5
Research design ................................................................................................................. 5
Metaforest Moderator analyses .............................................................................................. 6
Results ............................................................................................................................... 6
Moderator importance analyses.......................................................................................... 7
Moderation effect plots ...................................................................................................... 8
Materials versus immaterial ........................................................................................... 8
DV category .................................................................................................................. 9
Replica .......................................................................................................................... 9
Mere exposure ............................................................................................................. 10
Legal/factual ownership ............................................................................................... 10
Loss aversion ............................................................................................................... 10
Implicit versus explicit ownership ................................................................................ 12
PCurve analysis ................................................................................................................... 13
Summary ......................................................................................................................... 13
PCurve analysis graph ..................................................................................................... 13
Pcurve results .................................................................................................................. 13
Mere ownership effect meta-analysis: Supplementary 2
Pcurve interpretation:....................................................................................................... 15
Process ................................................................................................................................ 16
Search.............................................................................................................................. 16
Contacting authors ........................................................................................................... 16
Contact template .............................................................................................................. 16
Meta-analysis pre-registration .............................................................................................. 18
Introduction ..................................................................................................................... 18
Background ................................................................................................................. 18
The dependent variable: Evaluation/liking ................................................................... 18
The independent variable: Ownership .......................................................................... 18
Goals and research questions ........................................................................................... 19
Goal statement ............................................................................................................. 19
Research questions....................................................................................................... 19
Hypotheses ...................................................................................................................... 19
Main hypothesis ........................................................................................................... 19
Moderators .................................................................................................................. 19
Exploratory moderators................................................................................................ 20
Methods........................................................................................................................... 21
Description of essential elements ................................................................................. 21
Analysis plan ................................................................................................................... 23
Confirmatory analyses ................................................................................................. 23
Exploratory analyses .................................................................................................... 23
Answer the following final questions: .......................................................................... 23
Conflicts of Interest ..................................................................................................... 24
References ....................................................................................................................... 25
Deviations: Comparison of process versus pre-registration .................................................. 27
Further challenges and implications ..................................................................................... 27
Mere ownership effect meta-analysis: Supplementary 3
Open Science
Pre-registration, meta-analysis search and coding materials, open-science disclosures are
reported, with data and annotated RMarkdown code and output made available for reviewers
and readers on the Open Science Framework (OSF; https://osf.io/fdyqw/).
Disclosures
Data collection
Data collection was completed before conducting an analysis of the data.
Search, coding, and data collection ended in 2018 and the meta analysis covers the literature
up until that point. The manuscript has been going through rounds of review since.
Variables reporting
All variables collected for this meta-analysis are reported and included in the provided data.
Mere ownership effect meta-analysis: Supplementary 4
Planned moderators
Duration of ownership
There have been mixed views regarding whether the duration of ownership is a factor in the
mere ownership effect. On one hand, Strahilevitz and Loewenstein (1998) suggested that
people tend to value an object more immediately after owning it, though argued it may also
take some time for full sense of ownership to develop and reach maximal impact. They
demonstrated that favorable evaluations of an owned object would increase the longer the
ownership lasts, and this has been successfully replicated in subsequent studies (e.g., Shu &
Peck, 2011). On the other hand, some studies found that mere ownership effects occur even
before the ownership has been clearly defined (Peck & Shu, 2009).
The duration of ownership varies across existing studies. In some studies, participants rated
an object given to them in the experiment (e.g., Beggan, 1992), whereas in other studies,
participants evaluated an object that has been owned for a long period of time (e.g.,
Nesselroade, Beggan, & Allison, 1999). To clarify the impact of ownership duration on the
mere ownership effects, we predicted that the duration of ownership is positively related to
mere ownership effects, such that the mere ownership effects would be stronger the longer the
duration of ownership.
Actual versus replica ownership
In actual ownership, the evaluated object is owned by the individual, whereas in replica
ownership, the evaluated object is a replica - an object similar to the one owned. Past research
suggested that replicas may trigger weaker mere ownership effects than actual objects did. For
example, Barone et al. (1997) conducted a direct replication of Beggan’s studies (1992), but
their results were inconsistent with that of Beggan’s (1992) showing much smaller effect size.
Later, Beggan and Allison (1997) conducted a mini meta-analysis of their studies and
concluded that the Barone et al. (1997) manipulated ownership by asking participants to
evaluate a replica, which appeared to be a crucial departure from Beggan’s (1992)
manipulation in which the actual owned object was used. Beggan and Allison (1997) argued
that the weakened effects could perhaps be explained by participants’ weaker or no
connection with the replica compared to an object that is factually owned. Thus, we predicted
that mere ownership effects would be stronger when the target object is owned compared to
when the target object is a replica.
Explicit versus implicit ownership
We define explicit ownership as perceived ownership in the presence of actual ownership,
and implicit ownership as perceived ownership in the absence of actual ownership, such as
ownership imagery. Peck and Shu (2009) found that even implicit ownership through imagery
and/or touch could elicit individuals’ perception of ownership and improved their evaluations
of an object. It seems that both explicit and implicit ownership can induce the mere ownership
effects. Still, explicit ownership possibly produces a stronger sense of ownership than implicit
ownership. For example, Beggan and Brown (1994) found that people perceived a person to
have a stronger claim of ownership of an object when this person was pictured together with
the target object. Therefore, we predicted that the mere ownership effects would be stronger
when the ownership is explicit relative to implicit.
Loss aversion
The mere ownership effects are sometimes confounded with the endowment effect, that
people demand higher prices when selling an object than they would be willing to pay for it as
Mere ownership effect meta-analysis: Supplementary 5
buyers (Thaler, 1980). Selling implies a loss, and buying implies a gain. The negative affect
caused by a loss is larger than the positive affect caused by an equivalent gain (Kahneman &
Tversky, 1984). Applying this rationale of loss aversion to ownership, it is possible that
people set a higher price for an owned object in a transaction not because of ownership but
because of the anticipated negative feelings for forgoing the object. This idea has been
supported by some studies (e.g., Carmon & Ariely, 2000; Johnson, Häubl, & Keinan, 2007;
Kahneman, Knetsch, & Thaler, 1990), yet other studies demonstrated that it was not loss
aversion but perceived ownership association that induced the mere ownership effects (e.g.,
Maddux et al., 2010; Morewedge et al., 2009; Peck & Shu, 2009). Meanwhile, in mere
ownership effect experiments and many of the endowment effect experiments, it is common
to treat owners and sellers as interchangeable in simulated trades, leading to the problem that
potential loss and ownership are confounded in transaction situations (e.g. Walasek,
Matthews, & Rakow, 2015; Morewedge et al., 2009).
To tease apart the influences of potential loss and ownership, we set up two competing
hypotheses regarding the moderating role of loss aversion on the mere ownership effects.
Chatterjee, Irmak, and Rose (2013) found that when the object was perceived as part of the
self, selling became threatening and led to an enhanced mere ownership effect. Accordingly,
we predicted that the mere ownership effects would be stronger when there is potential loss
compared to no potential loss. Yet, it is possible that ownership alone is sufficient to induce
positive evaluation or liking of the owned object (Morewedge et al., 2009). Therefore, we also
predicted that the mere ownership effects would not be affected by loss aversion.
Importantly, we aimed to focus on mere ownership effects separate from that of the
endowment effect, to make a clear differentiation between the two phenomena. We therefore
limited the scope in the pre-registration of the meta-analysis to studies that do not contrast
buyers against sellers and/or willingness to pay (WTP) against willingness to accept (WTA).
We will further discuss this in the methods section.
Mere exposure
The mere exposure effect is the phenomenon that mere repeated exposure to an object
enhances favorable evaluations of the object (Zajonc, 1968). Since ownership often involves
more exposure to the owned object, it is unclear whether or to what extent mere ownership
effect is accounted by mere exposure (Beggan, 1992).
We set up different hypotheses regarding the moderating role of mere exposure on the mere
ownership effects. On one hand, we expected that the mere ownership effects would be
stronger with longer exposure. On the other hand, Beggan (1992) revealed that the mere
ownership effect was not affected by the length of exposure or the amount of contact, leading
to the expectation that the mere ownership effect perhaps occurs regardless of exposure.
Material versus immaterial object
Research on mere ownership effect demonstrated the effects on both material objects such as
insulators and mug (e.g., Barone et al., 1997; Morewedge et al., 2009), and immaterial
objects, such as arguments (De Dreu & van Knippenberg, 2005), letters (Nuttin, 1987),
symbols (Feys, 1991), and time (Hoorens, Remmers, & van de Riet, 1999). We developed
competing hypotheses regarding the moderating effect of material versus immaterial objects -
that the mere ownership effect would be stronger for material objects over immaterial objects
against the hypothesis that the mere ownership effects would not be affected by the nature of
object (material vs. immaterial).
Research design
Mere ownership effect meta-analysis: Supplementary 6
In addition to the above, we also examined differences in research design (i.e. between-
subject versus within-subject).
Metaforest Moderator analyses
Results
## MetaForest results
##
## Type of analysis: MetaForest
## Number of studies: 41
## Number of moderators: 7
## Number of trees in forest: 500
## Candidate variables per split: 2
## Minimum terminal node size: 5
## OOB prediction error (MSE): 0.0774
## R squared (OOB): 0.2575
##
## Tests for Heterogeneity:
## tau2 tau2_SE I^2 H^2 Q-test df Q_p
## Raw effect sizes: 0.0638 0.0212 74.7160 3.9551 178.7430 40 0.0000
## Residuals (after MetaForest): 0.0428 0.0160 66.4833 2.9836 124.2003 40 0.0000
##
##
## Random intercept meta-analyses:
## Intercept se ci.lb ci.ub p
## Raw effect sizes: 0.4693 0.0491 0.3731 0.5655 0.0000
## Residuals (after MetaForest): -0.0022 0.0429 -0.0863 0.0820 0.9594
Mere ownership effect meta-analysis: Supplementary 7
Moderator importance analyses
Mere ownership effect meta-analysis: Supplementary 8
Moderation effect plots
Materials versus immaterial
Mere ownership effect meta-analysis: Supplementary 9
DV category
Replica
Mere ownership effect meta-analysis: Supplementary 10
Mere exposure
Legal/factual ownership
Loss aversion
Mere ownership effect meta-analysis: Supplementary 11
Mere ownership effect meta-analysis: Supplementary 12
Implicit versus explicit ownership
Mere ownership effect meta-analysis: Supplementary 13
PCurve analysis
We pre-registered conducting a pcurve analysis, yet the nested nature of the meta data and
lacking statistical reporting resulted in challenges to that analysis.
We ran an analysis of the studies that reported inferential statistics using
http://shinyapps.org/apps/p-checker/
These findings should be interpreted with caution.
Summary
We performed a p-curve analysis (Simonsohn, Nelson, & Simmons, 2014) to quantify the
evidence in support of the mere ownership effect. With an estimated power of 77% (90% CI
[61%, 88%]), we conclude that based on the combination test (Simonsohn, Simmons, &
Nelson, 2015) there is evidential value for the effect (contains evidential value right skew: z =
-7.77/-7.58, p < .0001; no evidential value, flatter than 33% power: z = 3.83/8.43, p > .9999).
See supplementary materials for further details.
PCurve analysis graph
Pcurve results
Mere ownership effect meta-analysis: Supplementary 14
Mere ownership effect meta-analysis: Supplementary 15
Pcurve interpretation:
P-Curve analysis combines the half and full p-curve to make inferences about evidential
value. In particular, if the half p-curve test is right-skewed with p<.05 or both the half and full
test are right-skewed with p<.1, then p-curve analysis indicates the presence of evidential
value. This combination test, introduced in Simonsohn, Simmons and Nelson (2015 .pdf)
'Better P-Curves' paper, is much more robust to ambitious p-hacking than the simple full p-
curve test is.
Here both conditions are met, indicating evidential value.
Similarly, p-curve analysis indicates that evidential value is inadequate or absent if the 33%
power test is p<.05 for the full p-curve or both the half p-curve and binomial 33% power test
are p<.1. Here neither condition is met; so p-curve does not indicate evidential value is
inadequate nor absent.
Mere ownership effect meta-analysis: Supplementary 16
Process
Search
We pre-registered the use of Google Scholar as the main database (for suitability for meta-
analyses see Gehanno, Rollin, & Darmoni, 2013; Martín-Martín, Orduna-Malea, Thelwall, &
López-Cózar, 2018; Walters, 2007).
Keyword: "mere ownership" OR "ownership effect" OR "psychological ownership" OR
"perceived ownership".
Search pattern: "(Beggan AND 1992) AND (“endowment effect” OR “mere ownership” OR
“ownership effect” OR “perceived ownership” OR “sense of ownership” OR “subjective
ownership” OR “possession” or “owner”) AND (ranking OR valuation OR attractiveness OR
price OR pricing OR liking OR value)".
References:
Gehanno, J. F., Rollin, L., & Darmoni, S. (2013). Is the coverage of Google Scholar enough
to be used alone for systematic reviews?. BMC Medical Informatics and Decision Making, 13,
7. DOI: 10.1186/1472-6947-13-7
Martín-Martín, A., Orduna-Malea, E., Thelwall, M., & López-Cózar, E. D. (2018). Google
Scholar, Web of Science, and Scopus: a systematic comparison of citations in 252 subject
categories. Retrieved August 2018, https://doi.org/10.31235/osf.io/42nkm
Walters, W. H. (2007). Google Scholar coverage of a multidisciplinary field. Information
Processing & Management, 43, 1121-1132. DOI: 10.1016/j.ipm.2006.08.006
Contacting authors
We contacted all authors of identified publications. We were unable to obtained unpublished
manuscripts beyond the identified manuscript through our search process.
Contact template
We are conducting a meta-analysis on the mere ownership effect (e.g., Beggan, 1992,
JPSP).
We recently completed a search of the literature and identified you as an author who
has published work on the topic, and so we are contacting you to ask for your
unpublished manuscripts and data to be included in the meta-analysis.
[The study you coauthored to be included: <IDENTIFIED PUBLICATION>]
We are especially interested in any relevant unpublished manuscripts or data that
cannot be found using regular literature search.
We would also appreciate references to your other published manuscripts and/or data
to make sure we included it in our meta.
If you have unpublished manuscripts, we would appreciate a copy and suggested
citation.
Alternatively, for unpublished manuscripts and/or data, the information we require for
inclusion is:
Mere ownership effect meta-analysis: Supplementary 17
A description of the manipulation and general description of the experimental
conditions.
For each experimental condition:
o Brief description of the condition
o Sample size
o Mean and standard deviation for each of the dependent variables
o Brief description of the measures/scales were used for the dependent
variables, and internal reliabilities if available/relevant.
Sample characteristics, such as: overall sample size, country, sample type
(students, MTurk, general population, etc.), mean age.
Reference to be used when citing this data.
If you only have raw data that has not yet been analyzed, then we would be happy to
help analyze it for inclusion. In such a case, please send us the dataset and a
description of the key variables described above relevant for the analysis.
Please send all relevant information and/or data to me at this email <EMAIL>
Mere ownership effect meta-analysis: Supplementary 18
Meta-analysis pre-registration
We pre-registered the meta-analysis on the Open Science Framework following a coding pre-
test and finalization of the coding sheet. Below is the pre-registered plan.
Introduction
Background
Ownership is the association between a person and an object (Heider, 1958). The sense of
ownership manifests itself in the meaning and emotion commonly associated with ‘MY’ or
‘MINE,’ and ‘OUR’ (Pierce, Kostova, & Dirks, 2003). In the mere ownership effect, the
psychological ownership of an object increases the perceived value of the object, and people
show greater liking for an owned object (Nuttin, 1985, 1987). Beggan (1992) demonstrated
that people would evaluate an object more favorably merely because they own it, with
participants in the ownership condition rating the object more favorably than participants in
the no ownership condition. The effect has since been shown for various other objects (e.g.,
Morewedge, Shu, Gilbert, & Wilson, 2009), as well as immaterial objects like suggestions
(Baer & Brown, 2012) and behaviors (Constable et al., 2016).
The dependent variable: Evaluation/liking
The effect is typically demonstrated by having participants evaluate, rate, price, or rank an
object.
The independent variable: Ownership
In the mere ownership effect, the independent variable is a manipulation of ownership. The
literature refers to ownership using a variety of different terms, such as ownership (Beggan,
1992; Nuttin, 1987), perceived ownership (Peck & Shu, 2009), psychological ownership (Shu
& Peck, 2011), sense of ownership, subjective ownership, or subjective sense of endowment
(Reb & Connolly, 2007).
There are several types of ownership, such as factual, legal, psychological-subjective (Reb &
Connolly, 2007), or implicit ownership such as by merely touching an object, touching an
image of an object, or imagining one owns an object (Peck & Shu, 2009; Peck & Shu, 2009;
Shu & Peck, 2011; Brasel & Gips, 2014).
In the present meta-analysis, we will focus on perceived and/or psychological ownership.
Legal or factual ownership is included only if had affected psychological ownership.
Mere ownership effect meta-analysis: Supplementary 19
Goals and research questions
Goal statement
In this meta-analysis, we aim to examine whether psychological ownership has an impact on
evaluation/liking of the object (confidence intervals do not include the null), determine
overall effect size, and explore potential factors that moderate the effect.
Research questions
1. Do people evaluate objects more favorably when they perceive they own the object?
2. What is the overall effect size for the bias?
3. What are factors affecting the bias?
Hypotheses
Main hypothesis
The main hypothesis for the meta-analysis main effect:
Hypothesis: Psychological ownership of an object increases evaluation/liking of that object.
Moderators
Duration of ownership
People adapt to ownership gradually and ownership duration could influence the valuation of
the object (Strahilevitz & Loewenstein, 1998; Shu & Peck, 2011). The longer the ownership
duration, the stronger the link between self and the owned object. We therefore expect that
mere ownership effect would be stronger the longer the people owned the object.
The duration of ownership will be coded as a dichotomous (0 = immediate or recent; 1 =
longer ownership; 99 = time is unclear).
Hypothesis: The impact of ownership on valuation/liking will be stronger in long compared
to short ownership duration.
Actual ownership vs. Similar/Replica ownership
We expect that mere ownership effect would be stronger when people rate an object they own
rather than a similar/replica object.
Object type will be coded (0 = a replica or an object similar to owned object, 1 = an owned
object; 99 = unclear).
Hypothesis: The impact of ownership on valuation/liking will be stronger when object is
owned compared to when the object is similar to or a replica or an owned object.
Implicit versus explicit ownership
Peck and Shu (2009) stated that “merely touching an object results in an increase in perceived
ownership in of that object” (p.434). They also found that ownership imagery can increase
non-owners’ perceived ownership of an object; participants in ownership imagery condition
showed a higher valuation of the object. The power of imagery, however, was eliminated by
touching. Physical association between individual and an object can increase the perceived
ownership (Beggan & Brown, 1994).
We expect that clearly stated ownership will be stronger than assumed ownership by means of
imagination, touch, physical presence, viewing etc.
Mere ownership effect meta-analysis: Supplementary 20
Emerging type will be coded (0 = implicit ownership (touching, imaginary; presence), 1 =
explicit ownership).
Hypothesis: The impact of ownership on valuation/liking will be stronger when ownership is
explicit compared to when implicit
Exploratory moderators
Loss aversion
Loss aversion, first demonstrated by Tversky and Kahneman as “losses loom larger than
gains” (Kahneman & Tversky, 1984, p. 346). In mere ownership effect, higher evaluation of
an object, according to Morewedge et al. (2009), because people are associated with the
object rather than forgoing this object to be painful.
When evaluating an object, although with perceived ownership of the object, people may face
potential risk to give it up. Based on Morewedge et al. (2009), we expect that the mere
ownership effect will not be affected by loss aversion, meaning - the possibility of a “loss”
will not impact the mere ownership effect.
In this case, a loss opportunity is the scenario or the situation indicates that the person is
facing the possibility of losing an object, through sale, by potentially giving it up for some
gain, etc.
Loss possibility will be coded (0 = no potential loss; 1 = potential loss)
Hypothesis loss #1: The impact of ownership on valuation/liking will be different from null
(null not included in confidence intervals) even when there is no possibility of loss.
Competing hypothesis loss aversion #2a: The impact of ownership on valuation/liking will be
even stronger with the possibility of loss.
Competing hypothesis loss aversion #2b: The impact of ownership on valuation/liking will
not be affected by the possibility of loss (criteria 1: z-test comparisons not significant; criteria
2: 95% confidence intervals overlapping).
Mere exposure
Zajonc (1968) proved in his experiment that “repeated exposure is a sufficient condition of
attitude enhancement” (p.21). The mere ownership effect, however, is not because of mere
exposure of an object, and Beggan (1992) had demonstrated that a longer exposure did not
lead to more favorable evaluation on an owned object.
Length of exposure will be coded (0 = same length of exposure = 0, 1 = different length of
exposure, 99 = unclear) , note: for owned and non-owned target
Hypothesis exposure #1: The impact of ownership on valuation/liking will be different from
null (null not included in confidence intervals) even when there is no exposure.
Competing hypothesis exposure #2a: The impact of ownership on valuation/liking will be
even stronger with exposure.
Competing hypothesis exposure #2b: The impact of ownership on valuation/liking will not be
affected by exposure (criteria 1: z-test comparisons not significant; criteria 2: 95% confidence
intervals overlapping).
Material/immaterial objects
Mere ownership effect meta-analysis: Supplementary 21
We will explore whether the effect is different when ownership is over a material object that
participants can see and potentially touch compared to an immaterial object (e.g., arguments,
letters).
Competing hypothesis material #1a: The impact of ownership on valuation/liking will be
even stronger for material objects.
Competing hypothesis material #1b: The impact of ownership on valuation/liking will be
even stronger for material objects.
Competing hypothesis exposure #1c: The impact of ownership on valuation/liking will not be
affected by whether the object is material or not.. (criteria 1: z-test comparisons not
significant; criteria 2: 95% confidence intervals overlapping).
Methods
Description of essential elements
Design
- Independent variable:
o Ownership of the object: (owned vs. not owned)
- Dependent variables:
o Valuation/Liking of the object
- Moderators (see moderators and coding in section A above).
Search Strategy
- Database: Google Scholar (for suitability for meta-analyses see Walters, 2007; Gehanno,
Rollin, & Darmoni, 2013).
- The following search terms were used to search the database systematically.
o General: mere ownership effect, Beggan
o Bias names: mere ownership effect, endowment effect, effect of mere
ownership, ownership effect, psychological ownership, perceived ownership
o IV related: perceived ownership / psychological ownership / ownership
history / sense of ownership / subjective ownership / subjective sense of
endowment / self-object associations / cognitive perspective / emotional
attachment / “mine” and “theirs” with ownership / possession / possession
enhancement / self-ownership / self-owned / other-ownership / other-owned /
o DV related: ranking / rank / ratings / rate / valuation / evaluation /
attractiveness / attraction / price / money / pricing / favorable/liking
- A scan of reference sections of found articles
- Search for “related articles” and “cited by” Google Scholar options of the identified
articles
- Contacting authors of identified articles to ensure full coverage and maximize access to
unpublished data and/or manuscripts
- Abstracts, tables and methods sections will be scanned to identify the relevance of a
source.
Eligibility criteria
- Ownership (IV) and measures of evaluation/liking (DV)
Inclusion criteria
- Experimental designs only
Mere ownership effect meta-analysis: Supplementary 22
- IV: A clear manipulation of ownership
- IV: Psychological or perceived ownership
- DV: evaluation/ranking/liking.
Exclusion criteria
- IV related:
a. Studies that only ownership (possession) with no perceived ownership
measure.
b. Studies that that confounds (combine) buying-selling with ownership-no
ownership.
c. Loss aversion studies
d. Studies about the name letter effects: name letter task / name-letter effect /
birthday effect / name letter bias / NameLetter Test / Name letter
preferences / birthday-number preferences / self-esteem / familiarity
e. Organizational psychological studies
f. Studies about trade that involves an evaluation of something other than the
target owned
- DV related:
a. Studies with ownership as the DV
b. Studies with the following as the DV: recall ease, memory, reaction time or
implicit evaluation
- Missing statistics are not reported: Studies which do not report crucial measures such as
mean or standard needed for the calculation of the effect size deviation will be excluded
from the sample.
- Correlational designs
Procedure for studies selection
Studies collected through the database searches will be assessed for their eligibility based on
their titles, abstract and content. One researcher will determine the adequacy of the study for
the meta-analysis and a second researcher will do the verification of the results. All the
decisions to exclude a study will be documented with reasons.
All decisions on inclusion and exclusion will be documented in any case.
Data extraction (coding)
- A coding sheet will be prepared and pre-tested
- The coding sheet and code book are attached
- The coding process for the pretests will be completed by two coders to ensure a high inter-
rater-reliability. Gaps identified will be documented and decisions will be reported in
detail.
- Once pre-test is completed, one coder will code all studies, the second coder will verify
coding.
Mere ownership effect meta-analysis: Supplementary 23
Analysis plan
We will use R and the metafor package the statistical analyses. Given the range of different
types of studies and experimental designs, we expect heterogeneity in the sample to be
relatively high. Therefore, a random effects model will be used.
All effect sizes will be converted to Cohen ‘s d and standardized to allow for a comparison.
Split conditions due to moderators in the original studies will be collapsed to allow for a
comparison of the main IV.
Whenever available, we will collect standardized effect sizes directly from authors of original
papers. We will check for the accuracy of these analyses based on provided information and
details. If unavailable we will use either descriptive statistics or inferential statistics to re-
compute standardized effect sizes.
All conversions and coding decisions will be documented and the original text will be
included in the coding sheet to allow for reproducibility.
Forest plots presenting the effect size of each study will be produced. A meta-analysis will
examine the overall main-effect, a meta-regression will be conducted to examine the impact
of the described moderators.
Statistical heterogeneity will be determined using the Tau2 test and quantified using I2, which
represents the percentage of total variation in a set of studies that is actually due to
heterogeneity. (Higgins, Thompson, Deeks, & Altman, 2003). This global meta-analysis will
yield a point estimate, confidence interval, and p-value, along with statistics for heterogeneity,
assessed using the Q-statistics, and the I^2 statistic. If there is indeed significant
heterogeneity, we will explore potential moderators
We will report an analysis for the presence of publication bias, including funnel plots and
statistical tests for publication bias (minimum: publication status as a moderator, compare
effects for only published findings) and asymmetry (minimum: trim and fill, rank test,
Egger’s unweighted regression symmetry test).
We will also conduct a p-curve (Simonsohn, Nelson, & Simmons, 2014; Simmons, &
Simonsohn, 2017) and a p-uniform test (van Aert & van Assen, 2017).
We aim to share all coding and R code with reviewers and the academic community using the
Open Science Framework.
Confirmatory analyses
We will test for the hypotheses detailed in section A “Hypotheses” using a random-effects
meta model.
We plan a-priori to also conduct meta-analyses on subsets of the data, in particular, we will
split the data by study design and IV/DV types.
Exploratory analyses
The coding sheet includes many other collected variables. We expect that will conduct
additional exploratory on some of these variables, but those will be considered exploratory.
We also expect that additional hypotheses and possible coding moderators will be identified
as we examine the papers and collected studies.
In both cases, we will explicitly declare these analyses as exploratory.
Answer the following final questions:
Mere ownership effect meta-analysis: Supplementary 24
Has data collection begun for this project?
o No, data collection has not begun
o Yes, data collection is underway or complete
If data collection has begun, have you looked at the data?
o Yes
o No
The (estimated) start and end dates for this project are (optional):
Any additional comments before I pre-register this project (optional):
Conflicts of Interest
There are no conflicts of interest to report.
Mere ownership effect meta-analysis: Supplementary 25
References
Baer, M., & Brown, G. (2012). Blind in one eye: How psychological ownership of ideas
affects the types of suggestions people adopt. Organizational Behavior and Human Decision
Processes, 118, 60-71. http://dx.doi.org/10.1016/j.obhdp.2012.01.003
Beggan, J. (1992). On the social nature of nonsocial perception: The mere ownership
effect. Journal of Personality and Social Psychology, 62, 229-237.
http://dx.doi.org/10.1037//0022-3514.62.2.229
Beggan, J., & Brown, E. (1994). Association as a Psychological Justification for
Ownership. The Journal of Psychology, 128, 365-380.
http://dx.doi.org/10.1080/00223980.1994.9712741
Brasel, S., & Gips, J. (2014). Tablets, touchscreens, and touchpads: How varying touch
interfaces trigger psychological ownership and endowment. Journal of Consumer
Psychology, 24, 226-233. http://dx.doi.org/10.1016/j.jcps.2013.10.003
Constable, M., Bayliss, A., Tipper, S., Spaniol, A., Pratt, J., & Welsh, T. (2016). Ownership
Status Influences the Degree of Joint Facilitatory Behavior. Psychological Science, 27, 1371-
1378. http://dx.doi.org/10.1177/0956797616661544
Gehanno, J. F., Rollin, L., & Darmoni, S. (2013). Is the coverage of Google Scholar enough
to be used alone for systematic reviews. BMC medical informatics and decision making, 13,
7.
Heider, F. (1958). The Psychology of Interpersonal Relations. Psychology Press.
Higgins, J. P., Thompson, S. G., Deeks, J. J., & Altman, D. G. (2003). Measuring
inconsistency in meta-analyses. BMJ: British Medical Journal, 327, 557.
Kahneman, D., & Tversky, A. (1984). Choices, values, and frames. American
Psychologist, 39, 341.
Morewedge, C., Shu, L., Gilbert, D., & Wilson, T. (2009). Bad riddance or good rubbish?
Ownership and not loss aversion causes the endowment effect. Journal of Experimental
Social Psychology, 45, 947-951. http://dx.doi.org/10.1016/j.jesp.2009.05.014
Nuttin, J. M. (1985). Narcissism beyond Gestalt and awareness: The name letter
effect. European Journal of Social Psychology, 15, 353-361.
Nuttin, J. M. (1987). Affective consequences of mere ownership: The name letter effect in
twelve European languages. European Journal of Social Psychology, 17, 381-402.
Peck, J., & Shu, S. (2009). The Effect of Mere Touch on Perceived Ownership. Journal of
Consumer Research, 36, 434-447. http://dx.doi.org/10.1086/598614
Pierce, J., Kostova, T., & Dirks, K. (2003). The state of psychological ownership: Integrating
and extending a century of research. Review of General Psychology, 7, 84-107.
http://dx.doi.org/10.1037//1089-2680.7.1.84
Reb, J., & Connolly, T. (2007). Possession, feelings of ownership and the endowment
effect. Judgment and Decision Making, 2, 107.
Shu, S., & Peck, J. (2011). Psychological ownership and affective reaction: Emotional
attachment process variables and the endowment effect. Journal of Consumer Psychology, 21,
439-452. http://dx.doi.org/10.1016/j.jcps.2011.01.002
Simmons, J. P., & Simonsohn, U. (2017). Power posing: P-curving the
evidence. Psychological Science, 28, 687-693.
Mere ownership effect meta-analysis: Supplementary 26
Simonsohn, U., Nelson, L. D., & Simmons, J. P. (2014). P-curve: a key to the file-
drawer. Journal of Experimental Psychology: General, 143, 534.
Strahilevitz, M., & Loewenstein, G. (1998). The Effect of Ownership History on the
Valuation of Objects. Journal of Consumer Research, 25, 276-289.
http://dx.doi.org/10.1086/209539
van Aert, R. C., & van Assen, M. A. (2017). Examining reproducibility in psychology: A
hybrid method for combining a statistically significant original study and a replication.
Walters, W. H. (2007). Google Scholar coverage of a multidisciplinary field. Information
Processing & Management, 43, 1121-1132.
Zajonc, R. (1968). Attitudinal effects of mere exposure. Journal of Personality and Social
Psychology, 9, 1-27. http://dx.doi.org/10.1037/h0025848
Mere ownership effect meta-analysis: Supplementary 27
Deviations: Comparison of process versus pre-registration
We note several deviations from the pre-registration protocol:
We reported Hedge’s g rather than the pre-registered Cohen’s d, to address reviewer
comments we received on a pre-print. The effects and results were quite similar, yet Hedge's g
is considered more accurate as it takes into account sample size.
We also note we originally planned to examine publication status as a moderator, yet we were
unable to obtain enough unpublished manuscripts or data to conduct such an analysis.
We discussed coding of legal ownership prior to pre-registration, and this was included in the
pre-registered coding this, yet the competing hypotheses were left out of the pre-registration.
We regard this moderator as exploratory.
We pre-registered the exclusion criteria of "Studies that only ownership (possession) with
no perceived ownership measure.". When coding we realized that this was a big vague since
we did not state what having such a measure entails. We interpreted this in the broadest sense
- that the coders agree that there was a clear indication that participants perceived ownership
(a scale measuring psychological ownership, signing an ownership declaration, participants
being given an object, etc.).
Further challenges and implications
To address the challenges in the mere ownership literature, we resulted to strict
inclusion/exclusion criteria to rule out studies on related yet distinct phenomena and to focus
solely on mere ownership. Our inclusion/exclusion criteria may have introduced some
limitations. First, we excluded experiments that did not explicitly measure psychological
ownership. This helped ensure that the studied effect was driven by psychological ownership
but not by other factors. However, by doing so, we excluded a large number of studies, which
did not explicitly manipulate or measure ownership but may have still captured some aspects
of the mere ownership effect. It is possible that the effect of mere ownership is even more
robust and generalizable than shown in this meta-analysis. Second, we mainly included
published articles. Although we found no clear evidence for a publication bias in this meta-
analysis, we cannot rule out possible file-drawer issues and an over-estimation of the effect.
ResearchGate has not been able to resolve any citations for this publication.
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