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《社会心理学》课程教学资源（文献资料）attitude&stereotype——The Ontogeny of the Motivation That Underlies In-Group Bias

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Psychological Science 1–7 © The Author(s) 2014 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/0956797613516802 pss.sagepub.com Research Article 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, 516802PSSXXX10.1177/0956797613516802Buttelmann, BöhmThe Ontogeny of In-Group Bias research-article2014 Corresponding Author: David Buttelmann, University of Erfurt, Nordhaeuser Strasse 63, D-99089 Erfurt, Germany E-mail: david.buttelmann@uni-erfurt.de The Ontogeny of the Motivation That Underlies In-Group Bias David Buttelmann1,2 and Robert Böhm2,3 1 Kleinkindforschung in Thüringen Research Group, University of Erfurt; 2 Center for Empirical Research in Economics and Behavioural Sciences, University of Erfurt; and 3 School 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 Psychological Science OnlineFirst, published on January 28, 2014 as doi:10.1177/0956797613516802 Downloaded from pss.sagepub.com by Cai Xing on February 13, 2014

Buttelmann,Bobm 2012).However.given that all of these studies have member.In our research,in contrast,participants'giving focused on adole more negative items to an out-group membe r than to an group love and out-group ha ite dev In-group member and the neutral box sole indicate ently of e (e.g.,through reciprocal benefits:Trivers. 1971 important because it excluded the children's individual ren (Buttelmann,Zmyj.Daum,Carpen 2007. stech.1978) cedures used have not focused on revealing the spe cific motivations that underlie children's behavior. Materials and Method out-g oup hate is n not onl Participants and design For instance.to develop effective programs that may The participants were 45 children aged 6(mean age=6 reduce prejudice and discrimination in childhood.it is years 0 month age range =5 years 6 months to 6 years important to know 9 months;19 girls s,20 Doys)and 5o children age 8 (mea nee phenomen. 19 girls.17 dditi with members of the in-groun exceed interactions with 6-vear-olds were tested but were not included in the final members of the out-group in frequency and importance mple because they did not understand the experimer aporael,Caporael,9),in-group love tal game eover,as a resu of technical proble of the this hypothesis in a behavioral experiment in which6 and 8-year-olds participated in a computer-mediated participate in child-development studies in We chose these um-s V.Ihere were there 3 to 10 .e.g..Fehr et al..2008).Children subiects)(resources:positive vs.negative:within sub in each experimental session were randomly assigned to jects)design one of two groups (green or yellow).The use of artificial udes confounding vari Procedure real g ins acquired thre induction After the children had been Killen,2010)or the transmission of group-based attitudes the laboratory,they entered the laboratory and drew a parentsto childre n(C telli,Zogm heir group co ade third tor decisions when allocating 15 positive resources (e.g. one with a rreen and one with a vellow T-shirt wel. a balloon,a cookie,a teddy bear)and 15 negative comed the c hildren to their assigned groups in opposite (e.g..piec moldy f the laboratory. The puppe interacte uPpt【ha or a real mem the out-group member or a neutral box (ie an egalitarian their hair color (lack ys blond.counterbalanced with allocation)】 respect to group color between experimental sessic To investigate the underl ying group-ba d motiv. S1 in the Supplem nta availabl the cns e pup a in h the chil of a neutral option (ie.,the box).In previous research dren's identification with their un we rovided ther in-group love,out-group hate,or both could motivate the with a T-shint in their group's color and took pictures of dominant allocation of positive resources to an in-group each child wearing his or her T-shirt.Moreover,children

2 Buttelmann, Böhm 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 6- and 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 by Cai Xing on February 13, 2014

The Ontogeny of In-Group Bias of the same group were seated on the same side of the receiving the example item and a negative exclamation on not receiving it)and tha ororatory,opposhc the neither puppet would like to decorate ctive group's color ing the uppe nle iter and an expression of schadenfreude on not receiving it) Experimental game.Next,the instructor explained the After the explanation of the experimental game,the chil computer-me was programmed with dren were ano clantying question was dis aticall (ithout demonstrate the game's characteristics and behavioral quently completed 30 experimental trials (15 involving options.As displayed in Figure 1,the bottom of the positive items and 15 involving negative items).Iter one puppet was prete r the prete results and the fu and a butt After all had finisk enta ed the each picture (the left and right positions of the yellow retumed their T-shirts,and the pup and green puppets were counterbalanced between the children that group membership is really not impor. of a l half of the had was located between the pictures of the pu pets.A black ticipated in another experimental game directly befor square was presented in a top-centered position (see Fig the experiment reported here (a short break was pro 1).After a mouse lick on thi square,an item appearec the games).Ho ever,there were n was een the an tral position.roughly equidistant from all three button after each allocation decision.The instructor explained Allocations in the experiment were fictitious and had and schematically showed on whiteboard that no eal consequence for the recipients (i.e.,the pup mo mpared with rea low)group and that clicking on the white button would by the decision maker only if a behavioral norm of a put the item in the box,such that"no one would receive specific outcome distribution is opposite to other (i.e. this item."Thereafter,the black square reappearec and a sion makers personal)d clck again wa required to start the ext trial.Th Ir the on make able to resource and one with a positive resource speakin decision makers might be more likely to act in line with through the puppets,the experimenters demonstrated a salient behavioral norm (e.g.,fairness)and contrary to that both puppets would like to receive positive resources their personal distributional preference (e.g.,egocen (by having the puppet express a positive exclamation on trism)if the consequences of doing so are fictitious rathe b nuli fr n the ntal The displa are (a)the black displaved before and ce pre 1,2014

The Ontogeny of In-Group Bias 3 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 by Cai Xing on February 13, 2014

Buttelmann,Bobm than real.However.there is evidence that children if they predominantly care about derogating the out- younger than 9 years of age do not have sufficient self- group absolutely or relatively,they should allocate more control to suppress o1er whs (Houser 201 olds nle tive co likely not to discriminate between real and fictitious to that in the domain of positive resources,provides an outcomes. unambiguous index of children's pure out-group hate.To estimate e age and gender differenc we calculated alge Coding and analyses ems to the all The dependent variable was participants'allocations of member and the aggregated allocations to the box and the out-group (vs.the in-group)member and then com pared these scores among groups of participants item to the in-gr Results For positive resources,the 6-year-olds (n=45)allocated 10%of the resources co se Detwee ber,and 15% allocation (putting the item in the box).or a (o-D indicated a substantial in-group bias when we directly allocation (giving the item to the out-group member).We compared the percentages of resources given to the ageeaedalocatondecisicrsncfthe5poeicamdinl in-group member with negative resources separately and tra on test positive-and negative-resource domains,we compared between positive resources allocated to the in-groun items given to the in-group member with those given to member relative to the neutral box and the out-group Although revea membe W1 070 001,r it ig nple if allocating 90%of the items to the in a child allocated 2%of all positive items to the in-group to the out-group member.and%to the box. out-group cal statistical results for both types of analyses,Wilcoxon member,the ulting an in est, 0.0,p<0 88.T difference betwee msto the ev-51250 box,an egalitarian allocation (in which no one received versus neutral box and the positive item),in the majority of trials.Therefore,to out-group:Mann-Whitney =528.00,p=006,r .30 shed light on child ominant motivation, intergroup th age ith tions of items to the neutral box and to the out-group stronger level of discrimination among the 8-year-olds member and tested this sum against the allocations to the than among the 6-year-olds. in-group membe Asn previous research. ting scenario is one in which in serve as a motivatio in-grould Likewise.for negative resources.we agg regated the allo- (n=45)allocated 12%of the items to the in-group mem cations of items to the neutral box and to the in-group ber,51%of the items to the out-group member,and 37% member and tested th ns to the ems to the box (see Fig.2),which again revea of thei should not allocate negative resources to their in-g However,when we investigated whether out-group hate member and should not distinguish between allocations was the underlying motive for this behavior by also con to the neutral box and the out-group member.However, sidering egalitarian allocations (i.e.,we aggregated

4 Buttelmann, Böhm 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 by Cai Xing on February 13, 2014

The Ontogeny of In-Group Bias 5 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 0 10 20 30 40 50 60 70 80 90 100 In-Group Neutral Box Out-Group In-Group Neutral Box Out-Group Positive Resources Negative Resources Allocated Resources (%) 6-Year-Olds 8-Year-Olds 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. Downloaded from pss.sagepub.com by Cai Xing on February 13, 2014

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