Psychological Science
http://pss.sagepub.com/
The Ontogeny of the Motivation That Underlies In-Group Bias
David Buttelmann and Robert Böhm
Psychological Science 2014 25: 921 originally published online 28 January 2014
DOI: 10.1177/0956797613516802
The online version of this article can be found at:
http://pss.sagepub.com/content/25/4/921
Published by:
http://www.sagepublications.com
On behalf of:
Association for Psychological Science
Additional services and information for Psychological Science can be found at:
Email Alerts: http://pss.sagepub.com/cgi/alerts
Subscriptions: http://pss.sagepub.com/subscriptions
Reprints: http://www.sagepub.com/journalsReprints.nav
Permissions: http://www.sagepub.com/journalsPermissions.nav
>> Version of Record - Apr 9, 2014
OnlineFirst Version of Record - Jan 28, 2014
What is This?
Downloaded from pss.sagepub.com at TECHNISCHE HOCHSCHULE AACHEN on April 10, 2014
516802
research-article2014
PSSXXX10.1177/0956797613516802Buttelmann, BöhmThe Ontogeny of In-Group Bias
Research Article
The Ontogeny of the Motivation That
Underlies In-Group Bias
Psychological Science
2014, Vol. 25(4) 921­–927
© The Author(s) 2014
Reprints and permissions:
sagepub.com/journalsPermissions.nav
DOI: 10.1177/0956797613516802
pss.sagepub.com
David Buttelmann1,2 and Robert Böhm2,3
1
Kleinkindforschung in Thüringen Research Group, University of Erfurt; 2Center for Empirical
Research in Economics and Behavioural Sciences, University of Erfurt; and 3School of
Business and Economics, RWTH Aachen University
Abstract
Humans demonstrate a clear bias toward members of their own group over members of other groups in a variety of
ways. It has been argued that the motivation underlying this in-group bias in adults may be favoritism toward one’s
own group (in-group love), derogation of the out-group (out-group hate), or both. Although some studies have
demonstrated in-group bias among children and infants, nothing is known about the underlying motivations of this
bias. Using a novel game, we found that in-group love is already present in children of preschool age and can motivate
in-group-biased behavior across childhood. In contrast, out-group hate develops only after a child’s sixth birthday and
is a sufficient motivation for in-group-biased behavior from school age onward. These results help to better identify
the motivation that underlies in-group-biased behavior in children.
Keywords
in-group favoritism, out-group derogation, in-group bias, ontogeny, childhood development, intergroup dynamics,
cognitive processes, decision making, social cognition
Received 8/23/13; Revision accepted 11/21/13
When humans are faced with the challenge of allocating
resources among other persons, they often base their
decisions on specific characteristics of the possible recipients. One of the most important of these characteristics
is the recipients’ group memberships (Allport, 1954;
Brewer & Caporael, 2006). People tend to prefer the
members of their own groups (in-groups) and to discriminate against the members of other groups (outgroups) in social decision-making situations (Brewer,
1979; Hewstone, Rubin, & Willis, 2002; Tajfel & Turner,
1986). Given its severe negative consequences for human
societies, understanding and minimizing intergroup discrimination is an important challenge not only for the
social sciences but also for other fields. On one hand,
favoring one’s in-group over out-groups increases the ingroup’s absolute welfare. On the other hand, such favoritism decreases the welfare of the out-groups, both
absolutely and relative to the in-group. The motivations
that lead to these often interrelated consequences of ingroup bias and intergroup discrimination have been
labeled in-group love (or in-group favoritism) and outgroup hate (or out-group derogation; Brewer, 1999).
Whether in-group love, out-group hate, or both are
decisive for engagement in intergroup discrimination is
an old debate. Some authors have argued that loyalty to
and cohesion within the in-group and hatred of and contempt toward the out-group are inseparable motivations
that emerge simultaneously (Sherif, 1966; Sumner, 1906).
Other authors have argued that in-group bias and intergroup discrimination require positive attitudes toward
the in-group, whereas attitudes toward the out-group
may range from hatred to indifference and may even be
positive (although at a lower level than toward the ingroup; Allport, 1954). Supporting the latter view, recent
research has shown that group members prefer a behavioral option that displays merely an altruistic desire to
help the in-group rather than an option that (in addition)
actively hurts the out-group (De Dreu et al., 2010; Halevy,
Bornstein, & Sagiv, 2008; Halevy, Weisel, & Bornstein,
Corresponding Author:
David Buttelmann, University of Erfurt, Nordhaeuser Strasse 63,
D-99089 Erfurt, Germany
E-mail: [email protected]
Downloaded from pss.sagepub.com at TECHNISCHE HOCHSCHULE AACHEN on April 10, 2014
Buttelmann, Böhm
922
2012). However, given that all of these studies have
focused on adolescents or adults, the stage at which ingroup love and out-group hate develop in early childhood, as well as whether these developments occur
jointly or independently of each other, remains an open
question. Although behavioral research has shown strong
in-group bias and discrimination effects among infants
and children (Buttelmann, Zmyj, Daum, & Carpenter,
2013; Fehr, Bernhard, & Rockenbach, 2008; Kinzler,
Dupoux, & Spelke, 2007; Moore, 2009), the designs and
procedures used have not focused on revealing the specific motivations that underlie children’s behavior.
Investigating the developmental origins of in-group love
and out-group hate is important not only from a theoretical point of view but also from a practical perspective.
For instance, to develop effective programs that may
reduce prejudice and discrimination in childhood, it is
important to know the underlying cognitions and motivations that lead to these phenomena in the first place.
Given that, particularly in early childhood, interactions
with members of the in-group exceed interactions with
members of the out-group in frequency and importance
(Brewer & Caporael, 2006; Caporael, 1997), in-group love
should not only dominate out-group hate in intensity but
also precede it in the order of development. We tested
this hypothesis in a behavioral experiment in which 6and 8-year-olds participated in a computer-mediated
experimental game. We chose these age groups because
it has been shown that there are fundamental developmental changes with regard to distributional preferences
in early school years (see, e.g., Fehr et al., 2008). Children
in each experimental session were randomly assigned to
one of two groups (green or yellow). The use of artificial
groups excludes confounding variables, such as developmental differences in the conception of and reaction to
real groups acquired through social learning (Hughes,
Bigler, & Levy, 2007) and experience (McGlothlin &
Killen, 2010) or the transmission of group-based attitudes
from parents to children (Castelli, Zogmaister, & Tomelleri,
2009; Lam, Guerrero, Damree, & Enesco, 2011).
Participants independently made third-party mini–dictator decisions when allocating 15 positive resources (e.g.,
a balloon, a cookie, a teddy bear) and 15 negative
resources (e.g., pieces of broken glass, moldy toast, a
spider) to a puppet that shared the features of an ingroup member, a puppet that shared the features of an
out-group member, or a neutral box (i.e., an egalitarian
allocation).
To investigate the underlying group-based motivations, it was important not only to include allocations of
negative resources but also to give participants the choice
of a neutral option (i.e., the box). In previous research,
in-group love, out-group hate, or both could motivate the
dominant allocation of positive resources to an in-group
member. In our research, in contrast, participants’ giving
more negative items to an out-group member than to an
in-group member and the neutral box solely indicates
out-group hate. The fact that participants could not profit
from the allocated resources either directly or indirectly
(e.g., through reciprocal benefits; Trivers, 1971) was
important because it excluded the children’s individual
outcome-based preferences (e.g., self-interest) as a possible motivational confound (McClintock, 1974; Toda,
Shinotsuka, McClintock, & Stech, 1978).
Materials and Method
Participants and design
The participants were 45 children aged 6 (mean age = 6
years 0 months; age range = 5 years 6 months to 6 years
9 months; 19 girls, 26 boys) and 36 children aged 8 (mean
age = 7 years 11 months; age range = 7 years 2 months
to 8 years 9 months; 19 girls, 17 boys). Three additional
6-year-olds were tested but were not included in the final
sample because they did not understand the experimental game. Moreover, as a result of technical problems, 1
participant did not complete all the trials of the task and
had to be excluded from some of the analyses. Children
were recruited from a database of parents who had volunteered to participate in child-development studies in a
medium-sized German city. There were 14 experimental
sessions, each with 3 to 10 participants. The experiment
used a 2 (age group: 6-year-olds vs. 8-year-olds; between
subjects) × 2 (resources: positive vs. negative; within subjects) design.
Procedure
Group induction. After the children had been welcomed by a male experimenter (the instructor) outside
the laboratory, they entered the laboratory and drew a
lottery ticket that determined their group color (green or
yellow) and a computer-cubicle number. Two hand puppets (each operated by a different female experimenter),
one with a green and one with a yellow T-shirt, welcomed the children to their assigned groups in opposite
corners of the laboratory. The puppets interacted with
the children as real members of their groups. Besides
their group membership, the puppets differed only in
their hair color (black vs. blond, counterbalanced with
respect to group color between experimental sessions;
see Table S1 in the Supplemental Material available
online). The puppets’ speech followed a strict protocol
and was the same in both groups. To increase the children’s identification with their group, we provided them
with a T-shirt in their group’s color and took pictures of
each child wearing his or her T-shirt. Moreover, children
Downloaded from pss.sagepub.com at TECHNISCHE HOCHSCHULE AACHEN on April 10, 2014
The Ontogeny of In-Group Bias923
of the same group were seated on the same side of the
laboratory, opposite from the other group, and each side
of the laboratory was decorated with murals in the
respective group’s color.
Experimental game. Next, the instructor explained the
computer-mediated game, which was programmed with
z-Tree (Fischbacher, 2007). For this purpose, a computer
screen was displayed schematically on a whiteboard to
demonstrate the game’s characteristics and behavioral
options. As displayed in Figure 1, the bottom of the
screen contained pictures of each puppet—one puppet
in the left corner and one puppet in the right corner—
and a button in the respective group color underneath
each picture (the left and right positions of the yellow
and green puppets were counterbalanced between
experimental sessions; see Table S1 in the Supplemental
Material).
A picture of a box, with a white button underneath it,
was located between the pictures of the puppets. A black
square was presented in a top-centered position (see Fig.
1). After a mouse click on this square, an item appeared
at this location. This procedure was implemented to
make participants move the mouse cursor back to a central position, roughly equidistant from all three buttons,
after each allocation decision. The instructor explained
and schematically showed on the whiteboard that a
mouse click on the green (vs. the yellow) button would
award the item to the puppet of the green (vs. the yellow) group and that clicking on the white button would
put the item in the box, such that “no one would receive
this item.” Thereafter, the black square reappeared and a
mouse click again was required to start the next trial. The
instructor presented two examples, one with a negative
resource and one with a positive resource. Speaking
through the puppets, the experimenters demonstrated
that both puppets would like to receive positive resources
(by having the puppet express a positive exclamation on
receiving the example item and a negative exclamation
on not receiving it) and that neither puppet would like to
receive negative resources (by having the puppet express
an exclamation of disgust on receiving the example item
and an expression of schadenfreude on not receiving it).
After the explanation of the experimental game, the children were allowed to ask clarifying questions.
Working independently in their assigned cubicles
(without communicating with others), participants subsequently completed 30 experimental trials (15 involving
positive items and 15 involving negative items). Item
valence was pretested (for the pretest results and the full
list of items, see Table S2 in the Supplemental Material).
After all participants had finished the experiment, they
returned their T-shirts, and the puppets “explained” to
the children that group membership is really not important and that everybody is equal. The whole experiment
took about 25 min to complete.
Approximately half of the younger children had participated in another experimental game directly before
the experiment reported here (a short break was provided between the games). However, there were no
behavioral differences between those participants and
the children from their age group who had not participated in the preceding experiment.
Allocations in the experiment were fictitious and had
no real consequences for the recipients (i.e., the puppets). The use of fictitious incentives, compared with real
incentives, should produce different behavioral responses
by the decision maker only if a behavioral norm of a
specific outcome distribution is opposite to other (i.e.,
the decision maker’s personal) distributional preferences
and if the decision maker is able to resist these other
preferences. For instance, to increase their social image,
decision makers might be more likely to act in line with
a salient behavioral norm (e.g., fairness) and contrary to
their personal distributional preference (e.g., egocentrism) if the consequences of doing so are fictitious rather
Fig. 1. Example stimuli from the experimental game. The displays shown here are (a) the black-square presentation (displayed before and
after each trial) and (b) a negative-resource presentation (of a spider).
Downloaded from pss.sagepub.com at TECHNISCHE HOCHSCHULE AACHEN on April 10, 2014
Buttelmann, Böhm
924
than real. However, there is evidence that children
younger than 9 years of age do not have sufficient selfcontrol to suppress their personal preferences (Houser,
Montinari, & Piovesan, 2012). In other words, 6-year-olds
and 8-year-olds, as represented by our sample, are very
likely not to discriminate between real and fictitious
outcomes.
Coding and analyses
The dependent variable was participants’ allocations of
resources in two types of third-party mini–dictator games:
allocation of positive resources and allocation of negative
resources. In the case of positive resources, participants
could choose between a (+1, 0) allocation (giving the
item to the in-group puppet), a (0, 0) allocation (putting
the item in the box), or a (0, +1) allocation (giving the
item to the out-group puppet). In the case of negative
resources, participants could choose between a (−1, 0)
allocation (giving the item to the in-group member), a (0,
0) allocation (putting the item in the box), or a (0, −1)
allocation (giving the item to the out-group member). We
aggregated allocation decisions of the 15 positive and 15
negative resources separately and transformed them into
percentages.
For participants’ level of intergroup discrimination in
positive- and negative-resource domains, we compared
items given to the in-group member with those given to
the out-group member. Although this difference reveals
participants’ relative preference for the in-group over the
out-group, it ignores egalitarian motives. For example, if
a child allocated 20% of all positive items to the in-group
member and 10% of all positive items to the out-group
member, the resulting 2-to-1 ratio would suggest an ingroup bias. However, this analysis ignores the fact that
the child allocated 70% of all positive items to the neutral
box, an egalitarian allocation (in which no one received
the positive item), in the majority of trials. Therefore, to
shed light on children’s dominant behavioral motivation,
one also needs to consider their egalitarian motives.
Thus, for positive resources, we aggregated the allocations of items to the neutral box and to the out-group
member and tested this sum against the allocations to the
in-group member. As in previous research, this measure
revealed children’s behavioral intergroup discrimination
motivated by in-group love, out-group hate, or both.
Likewise, for negative resources, we aggregated the allocations of items to the neutral box and to the in-group
member and tested this sum against the allocations to the
out-group member. If children care only about the absolute outcomes of their in-group (in-group love), they
should not allocate negative resources to their in-group
member and should not distinguish between allocations
to the neutral box and the out-group member. However,
if they predominantly care about derogating the outgroup absolutely or relatively, they should allocate more
negative resources to the out-group member relative to
the box and the in-group member combined. This comparison in the domain of negative resources, in contrast
to that in the domain of positive resources, provides an
unambiguous index of children’s pure out-group hate. To
estimate age and gender differences, we calculated algebraic difference scores from the allocations of positive
(vs. negative) items to the in-group (vs. the out-group)
member and the aggregated allocations to the box and
the out-group (vs. the in-group) member and then compared these scores among groups of participants.
Results
For positive resources, the 6-year-olds (n = 45) allocated
75% of the items to the in-group member, 10% of the
items to the out-group member, and 15% of the items to
the box (see Fig. 2 for allocation percentages), which
indicated a substantial in-group bias when we directly
compared the percentages of resources given to the
in-group member with those given to the out-group
member, Wilcoxon test, T + = 990.00, p < .001, r = .86.
Furthermore, in-group love and out-group hate clearly
dominated egalitarianism, as indicated by the contrast
between positive resources allocated to the in-group
member relative to the neutral box and the out-group
member, Wilcoxon test, T + = 907.50, p < .001, r = .66. The
8-year-olds (n = 36) also showed a clear in-group bias by
allocating 90% of the items to the in-group member, 4%
to the out-group member, and 6% to the box, with identical statistical results for both types of analyses, Wilcoxon
test, T + = 666.00, p < .001, r = .88. The difference between
the age groups was significant—allocations to in-group
versus out-group: Mann-Whitney U = 512.50, p = .004,
r = .32; allocations to in-group versus neutral box and
out-group: Mann-Whitney U = 528.00, p = .006, r = .30.
Thus, if intergroup discrimination can be motivated by
both in-group love and out-group hate, both age groups
showed considerable in-group-biased allocations, with a
stronger level of discrimination among the 8-year-olds
than among the 6-year-olds.
The more interesting scenario is one in which ingroup love may not serve as a motivation for in-groupbiased behavior: For negative resources, the 6-year-olds
(n = 45) allocated 12% of the items to the in-group member, 51% of the items to the out-group member, and 37%
of the items to the box (see Fig. 2), which again revealed
a significant preference for the in-group relative to the
out-group, Wilcoxon test, T + = 832.00, p < .001, r = .78.
However, when we investigated whether out-group hate
was the underlying motive for this behavior by also considering egalitarian allocations (i.e., we aggregated
Downloaded from pss.sagepub.com at TECHNISCHE HOCHSCHULE AACHEN on April 10, 2014
The Ontogeny of In-Group Bias925
6-Year-Olds
8-Year-Olds
100
90
Allocated Resources (%)
80
70
60
50
40
30
20
10
0
In-Group
Neutral Box
Out-Group
Positive Resources
In-Group
Neutral Box
Out-Group
Negative Resources
Fig. 2. Mean percentage of allocated resources as a function of age group, recipient (in-group member,
out-group member, or neutral box), and resource domain (positive or negative). Error bars show 95%
confidence intervals.
resources allocated to the in-group member and to the
neutral box and compared this sum with the allocations
to the out-group member), mere out-group hate did not
appear to be a significant behavioral motivation in this
age group, Wilcoxon test, T + = 477.50, p = .957, r = .01.
The 8-year-olds (n = 35) allocated 4% of the items to the
in-group member, 71% to the out-group member, and
25% to the box, which indicated a significant preference
for the in-group relative to the out-group, Wilcoxon test,
T + = 630.00, p < .001, r = .87. In contrast to the results
found for the younger children, the comparison of 8-yearolds’ allocations to the in-group and the neutral box with
those to the out-group revealed a significant difference,
Wilcoxon test, T + = 555.50, p < .001, r = .67, which indicated that out-group hate was the dominant motivation
for the 8-year-olds’ distributions of negative resources.
Age differences were again significant—allocations to ingroup versus out-group: Mann-Whitney U = 417.00, p <
.001, r = .40; allocations to in-group and neutral box versus out-group: Mann-Whitney U = 484.00, p = .003, r =
.33. Overall, the results indicated that in-group love is
already present in children of preschool age and can
motivate in-group-biased behavior, whereas out-group
hate develops only after a child’s sixth birthday and is
not sufficient to induce in-group-biased behavior before
that age.
Another indicator of the importance of out-group hate
for children’s level of intergroup discrimination is the correlation between intergroup discrimination in the domain
of positive and negative resources. This correlation was
stronger for the 8-year-olds, rs = .61, p < .001, than for
the 6-year-olds, rs = .30, p = .048, which provided further
evidence that the importance of out-group hate as
an underlying behavioral motivation increases with a
child’s age.
In addition to these main findings, our analyses yielded
an interesting result: There were no gender effects in any
of the analyses in the group of 6-year-olds (all ps ≥ .300).
However, gender differences did appear among the
8-year-olds. For positive resources, 8-year-old boys (n =
17) and girls (n = 19) respectively allocated 94% and 86%
of the items to the in-group member, 2% and 6% of the
items to the out-group member, and 5% and 8% of the
items to the box, which yielded a significant gender
effect in in-group bias when we compared the difference
scores for the allocations of positive items to the in-group
member and the aggregated allocations to the neutral
box and to the out-group member, Mann-Whitney U =
102.00, p = .046, r = .33. For negative resources, 8-yearold boys (n = 16) and girls (n = 19) respectively allocated
approximately 3% and 5% of the items to the in-group
member, 84% and 60% of the items to the out-group
Downloaded from pss.sagepub.com at TECHNISCHE HOCHSCHULE AACHEN on April 10, 2014
Buttelmann, Böhm
926
member, and 13% and 35% of the items to the box. These
differences indicated an even larger gender gap in ingroup bias when motivated by pure out-group hate,
Mann-Whitney U = 58.00, p = .002, r = .53.
Discussion
Our aim in the current study was to investigate whether
6- and 8-year-olds show an in-group bias in their allocation of positive and negative resources. Specifically, we
wanted to find out what motivations underlie in-groupbiased behavior among children. We developed a new
experimental game based on a behavioral measure that
allowed us to discriminate between positive and negative
group-based preferences, that is, in-group love and outgroup hate. Both age groups showed a clear in-group
bias in both domains of resources, positive and negative.
With regard to the underlying motivations, however, our
results showed a primacy of in-group love relative to outgroup hate in human ontogeny. When both in-group love
and out-group hate were able to serve as a behavioral
motivation (i.e., in the allocation of positive resources),
there was already substantial intergroup discrimination
among the 6-year-olds, which became even stronger
among the 8-year-olds. In contrast, when in-group love
was excluded as a potential source of this effect (i.e., in
the allocation of negative resources), we found out-group
hate to be a behavioral motivation for intergroup discrimination among the 8-year-olds only. Whereas the
younger children only prevented their in-group from
receiving negative items, the older children intentionally
harmed the out-group by giving the majority of negative
items to the out-group rather than putting them in the
neutral box (i.e., an egalitarian allocation). Thus, we conclude that in-group love develops before out-group hate
in human ontogeny. Accordingly, the positive consequences for one’s own group constitute the foundation of
in-group bias and discrimination, whereas the negative
consequences for other groups become a behavioral
motivation only at a later stage in human development.
It is interesting that among 8-year-olds, boys in particular showed out-group hate. From an evolutionary
perspective, there are good reasons for why males are
more prone than are females to engage in competitive
intergroup conflict (e.g., the male-warrior hypothesis;
Van Vugt, De Cremer, & Janssen, 2007), which is likely to
be reinforced through cultural processes. This gender
gap is also consistent with other research findings that
have indicated that it is mainly boys who show parochial
altruism (Fehr et al., 2008). Our study, however, provides
the first evidence that differences in group-based preferences (i.e., out-group hate) between boys and girls may,
at least partially, contribute to a gender gap in children’s
competitive orientation (e.g., Gneezy & Rustichini, 2004;
Moely, Skarin, & Weft, 1979).
The current study leaves some questions unanswered.
Specifically, it is unclear whether we were able to exclude
or control for all of the demand characteristics of our
task. We tried to keep them as low as possible by making
it clear that both puppets would like to receive positive
resources and avoid negative resources and that the children’s allocations would not result in any personal gains
or losses. Furthermore, in the current study, we used fictitious instead of real outcomes. Although we have argued
that this should not be a problem for children at the ages
of our participants, future research should include real
outcomes. For instance, one could provide recipients
with an endowment (of, e.g., candy) that may increase
(positive domain) or decrease (negative domain) as a
function of participants’ allocations. Finally, there might
be different motivations that underlie the conception of
out-group hate: to absolutely harm the out-group or to
maximize the relative difference between the in-group
and the out-group. Until now, these differences in motivation have not been distinguished empirically. Refining
the distinction between competitiveness and pure harm
on a behavioral level may be a direction for future
research.
The implications of the obtained findings are farreaching. The increase of cooperation and solidarity
within groups clearly is of utmost importance for human
societies. However, intragroup cooperation can sacrifice
collective efficiency if the aim is to harm other groups to
win an intergroup conflict (Böhm & Rockenbach, 2013).
An in-group’s absolute welfare, in particular, can be
severely damaged by engaging in long-lasting intergroup
conflicts. Given that our results suggest not only that ingroup love and out-group hate are independent of each
other but also that in-group love emerges before outgroup hate in human development, it is possible to affect
both of these motivations separately by building on
humans’ inherent prosocial nature. Children, and in particular boys, should be taught as early as preschool age
that intragroup cooperation and loyalty are valuable and
beneficial for humanity, and even for their own group in
the long run, only if they do not imply out-group derogation at the same time.
Author Contributions
D. Buttelmann and R. Böhm designed the study and collected
the data. D. Buttelmann analyzed the data. Both authors drafted
the manuscript and approved the final version of the manuscript for submission.
Acknowledgments
The authors are grateful to their students M. Aßmann, I. Dübner,
and K. Gerst, who provided excellent research assistance. We
thank M. Pigors for valuable advice on technical implementation, the research group at the Center for Empirical Research in
Economics and Behavioral Sciences for inspiring discussions,
Downloaded from pss.sagepub.com at TECHNISCHE HOCHSCHULE AACHEN on April 10, 2014
The Ontogeny of In-Group Bias927
and K. Gellén for her helpful comments on an earlier draft of
the manuscript. This research was carried out in accordance
with the provisions of the World Medical Association Declaration
of Helsinki.
Declaration of Conflicting Interests
The authors declared that they had no conflicts of interest with
respect to their authorship or the publication of this article.
Supplemental Material
Additional supporting information may be found at http://pss
.sagepub.com/content/by/supplemental-data
References
Allport, G. W. (1954). The nature of prejudice. Cambridge, MA:
Addison-Wesley.
Böhm, R., & Rockenbach, B. (2013). The inter-group comparison–
intra-group cooperation hypothesis: Comparisons between
groups increase efficiency in public goods provision. PLoS
ONE, 8(2), e56152. Retrieved from http://www.plosone.org/
article/info%3Adoi%2F10.1371%2Fjournal.pone.0056152
Brewer, M. B. (1979). In-group bias in the minimal intergroup
situation: A cognitive-motivational analysis. Psychological
Bulletin, 86, 307–324. doi:10.1037/0033-2909.86.2.307
Brewer, M. B. (1999). The psychology of prejudice: Ingroup
love and outgroup hate? Journal of Social Issues, 55, 429–
444. doi:10.1111/0022-4537.00126
Brewer, M. B., & Caporael, L. R. (2006). An evolutionary perspective on social identity: Revisiting groups. In M. Schaller,
J. Simpson, & D. Kenrick (Eds.), Evolution and social
psychology (pp. 143–161). New York, NY: Psychology
Press.
Buttelmann, D., Zmyj, N., Daum, M., & Carpenter, M. (2013).
Selective imitation of in-group over out-group members
in 14-month-old infants. Child Development, 84, 422–428.
doi:10.1111/j.1467-8624.2012.01860.x
Caporael, L. R. (1997). The evolution of truly social cognition:
The core configurations model. Personality and Social
Psychology Review, 1, 276–298. doi:10.1207/s15327957
pspr0104_1
Castelli, L., Zogmaister, C., & Tomelleri, S. (2009). The transmission of racial attitudes within the family. Developmental
Psychology, 45, 586–591. doi:10.1037/a0014619
De Dreu, C. K. W., Greer, L. L., Handgraaf, M. J. J., Shalvi,
S., Van Kleef, G. A., Baas, M., . . . Feith, S. W. W. (2010).
The neuropeptide oxytocin regulates parochial altruism in
intergroup conflict among humans. Science, 328, 1408–
1411.
Fehr, E., Bernhard, H., & Rockenbach, B. (2008). Egalitarianism
in young children. Nature, 454, 1079–1083. doi:10.1038/
nature07155
Fischbacher, U. (2007). z-Tree: Zurich toolbox for ready-made
economic experiments. Experimental Economics, 10, 171–
178. doi:10.1007/s10683-006-9159-4
Gneezy, U., & Rustichini, A. (2004). Gender and competition
at a young age. American Economic Review, 94, 377–381.
doi:10.1257/0002828041301821
Halevy, N., Bornstein, G., & Sagiv, L. (2008). “In-group love”
and “out-group hate” as motives for individual participation
in intergroup conflict: A new game paradigm. Psychological
Science, 19, 405–411.
Halevy, N., Weisel, O., & Bornstein, G. (2012). “In-group love”
and “out-group hate” in repeated interaction between
groups. Journal of Behavioral Decision Making, 25, 188–
195. doi:10.1002/bdm.726
Hewstone, M., Rubin, M., & Willis, H. (2002). Intergroup bias.
Annual Review of Psychology, 53, 575–604. doi:10.1146/
annurev.psych.53.100901.135109
Houser, D., Montinari, N., & Piovesan, M. (2012). Private and
public decisions in social dilemmas: Evidence from children’s behavior. PLoS ONE, 7(8), e41568. Retrieved from
http://www.plosone.org/article/info%3Adoi%2F10.1371%
2Fjournal.pone.0041568
Hughes, J. M., Bigler, R. S., & Levy, S. R. (2007). Consequences of
learning about historical racism among European American
and African American children. Child Development, 78,
1689–1705. doi:10.1111/j.1467-8624.2007.01096.x
Kinzler, K. D., Dupoux, E., & Spelke, E. S. (2007). The native
language of social cognition. Proceedings of the National
Academy of Sciences, USA, 104, 12577–12580. doi:10.1073/
pnas.0705345104
Lam, V., Guerrero, S., Damree, N., & Enesco, I. (2011). Young
children’s racial awareness and affect and their perceptions about mothers’ racial affect in a multiracial context.
British Journal of Developmental Psychology, 29, 842–864.
doi:10.1348/2044-835X.002013
McClintock, C. G. (1974). Development of social motives in
Anglo-American and Mexican-American children. Journal
of Personality and Social Psychology, 29, 348–354.
doi:10.1037/h0036019
McGlothlin, H., & Killen, M. (2010). How social experience is
related to children’s intergroup attitudes. European Journal
of Social Psychology, 40, 625–634. doi:10.1002/ejsp.733
Moely, B. E., Skarin, K., & Weft, S. (1979). Sex differences in
competition-cooperation behavior of children at two age
levels. Sex Roles, 5, 329–342.
Moore, C. (2009). Fairness in children’s resource allocation
depends on the recipient. Psychological Science, 20, 944–
948. doi:10.1111/j.1467-9280.2009.02378.x
Sherif, M. (1966). In common predicament: Social psychology of intergroup conflict and cooperation. Boston, MA:
Houghton Mifflin.
Sumner, W. G. (1906). Folkways: A study of the sociological importance of usages, manners, customs, mores, and
morals. Retrieved from http://www.gutenberg.org/files/
24253/24253-h/24253-h.htm
Tajfel, H., & Turner, J. C. (1986). The social identity theory of
intergroup behavior. In S. Worchel & W. G. Austin (Eds.),
Psychology of intergroup relations (2nd ed., pp. 7–24).
Chicago, IL: Nelson-Hall.
Toda, M., Shinotsuka, H., McClintock, C. G., & Stech, F. J. (1978).
Development of competitive behavior as a function of culture, age, and social comparison. Journal of Personality
and Social Psychology, 36, 825–839. doi:10.1037//00223514.36.8.825
Trivers, R. L. (1971). The evolution of reciprocal altruism.
Quarterly Review of Biology, 46, 35–57.
Van Vugt, M., De Cremer, D., & Janssen, D. (2007). Gender differences in cooperation and competition: The male-warrior
hypothesis. Psychological Science, 18, 19–23.
Downloaded from pss.sagepub.com at TECHNISCHE HOCHSCHULE AACHEN on April 10, 2014