《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

Psychological Sclence OnlineFirst,published on January 28,2014 as dol:10.1177/0956797613516802 Research Article PSYCHO The Ontogeny of the Motivation That The Author(s)2014 Underlies In-Group Bias 0.1177 567y761351602 SAGE David Buttelmann'2 and Robert Bohm2> Business and Economics,RWTH Aachen University Abstract r bias toward membe s of thei own group over members of other groups in a variety of een argue rlying this in-group one: dem ated ir n hias ar hildren and infar othin is knon out the s of thi bias.Using a novel game,we found that in-group love is already present in children of preschool age and can motivate group-biased behavior across chilhood.n contrast,out-group hate develops only after a child's sixth birthday and the mnnmnaianorngop nool age onward. Keywords n bis,ny chiod developmnrp dyn Received /2/Revision accepted 11/21/13 Whether in-group love,out-group hate,or both are the e th or engagement and cohesion within the in-group and hatred of and con is the recipients'group memberships (Allport,1954; tempt toward the out-group are inseparable motivation Brewer Caporael emerge simultaneousl (Sherif,1966;Sumner 1906 0 ave arguec nat in-group sand inte ups)in social decision-making situations (Brewer, the in-group.whereas attitudes toward the out-grour 1979:Hewstone,Rubin,Willis,2002:Taifel Turner, may range from hatred to indifference and may even be 1986).Given its severe negative consequences for human positive (although at a lower leve than toward the in aing and m imizing intergroup group: Supporting the latter favoring one's in-group over out-groups increases the in- help the in-group rather than an option that (in addition) group's absolute velfare.On the other hand,such favo actively hurts the out-group (De Dreu et al..2010:Halevy it-groups, Bornstein,Sagiv,2008:Halevy,Weisel,Bornstein that lead to these ences of in- Corr nding author: mpm group bate (or out-group derogation:Brewer, 1999 1,201

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 recip￾ients. 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 dis￾criminate against the members of other groups (out￾groups) 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 dis￾crimination 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 in￾group’s absolute welfare. On the other hand, such favor￾itism 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 in￾group bias and intergroup discrimination have been labeled in-group love (or in-group favoritism) and out￾group 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 con￾tempt toward the out-group are inseparable motivations that emerge simultaneously (Sherif, 1966; Sumner, 1906). Other authors have argued that in-group bias and inter￾group 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 in￾group; Allport, 1954). Supporting the latter view, recent research has shown that group members prefer a behav￾ioral 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 in￾group love and out-group hate develop in early child￾hood, 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 spe￾cific motivations that underlie children’s behavior. Investigating the developmental origins of in-group love and out-group hate is important not only from a theoreti￾cal 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 motiva￾tions 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 develop￾mental 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 develop￾mental 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–dicta￾tor 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 in￾group 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 motiva￾tions, 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 pos￾sible 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 experimen￾tal 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 vol￾unteered 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 sub￾jects) design. Procedure Group induction. After the children had been wel￾comed 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 pup￾pets (each operated by a different female experimenter), one with a green and one with a yellow T-shirt, wel￾comed 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 chil￾dren’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 cen￾tral 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 yel￾low) 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 chil￾dren were allowed to ask clarifying questions. Working independently in their assigned cubicles (without communicating with others), participants subse￾quently 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 impor￾tant and that everybody is equal. The whole experiment took about 25 min to complete. Approximately half of the younger children had par￾ticipated in another experimental game directly before the experiment reported here (a short break was pro￾vided between the games). However, there were no behavioral differences between those participants and the children from their age group who had not partici￾pated in the preceding experiment. Allocations in the experiment were fictitious and had no real consequences for the recipients (i.e., the pup￾pets). 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., egocen￾trism) 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 self￾control 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 in￾group 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 alloca￾tions 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 allo￾cations 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 abso￾lute 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 out￾group 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 com￾parison 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 alge￾braic 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 com￾pared 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 identi￾cal 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 in￾group love may not serve as a motivation for in-group￾biased behavior: For negative resources, the 6-year-olds (n = 45) allocated 12% of the items to the in-group mem￾ber, 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 con￾sidering egalitarian allocations (i.e., we aggregated Downloaded from pss.sagepub.com by Cai Xing on February 13, 2014

The Ontogeny of In-Group Bias 口6-Year-0lds口8-Year-0lds 100 90 60 0 20 10 0 In-Group Neutral Box Out-Group In-Group Neutral Box Out-Group Positive Resources Negative Resources fun )and re urce domain (po aiocdptetngoRmmandaae resources allocated to the in Another indicator of the importance of out-group hate for children's level of intergroup discrimination is the cor to the out-group member).mere out-group hate did not relation between intergroup discrimination in the domain appear to be of positive and negative resources.This correlation was age group.test. ted 402 onger fo o in-group member,71%to the out-group member.and evidence that the importance of out roun hate as 25%to the box,which indicated a significant preference an underlying behavioral motivation increases with a for the in-group relative to the out-group,Wilcoxon test, 30.00,p<.001, childs age n a ion to these main findings,our analyses yielde olds'allocations to the in-gre oup and the neutral box with of p f(all 0) those to the out-group revealed a significant difference However.gender differences did appear among the Wilcoxon test,T =555.50,p<.001,r=.67,which indi 8-year-olds.For positive resources,8-year-old boys (n t outgroup hate was the 1 19)respectively alloc ed 9 Age diffe to in. items to the out-g nd 5%6 and 8o of the oup versus out-group:Mann-Whitney U=41700 5 items to the box,which yielded a significant gende 001.r= .40;allocations to in-group and neutral box ver effect in in-group bias when we compared the difference oupMann-wh 0,p .005, ocations of pos ve items to th ent in children and can box and to the Mann-Whimey motivate in-group-biased behavior.whereas out-group 102.00.p=.046,r=.33.For negative resources,8-year hate develops only after a child's sixth birthday and is old boys (n=16)and girls (n 19)respectively allocated the items to the in-group 50% the o the ou-gou 1.201

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-year￾olds’ 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 indi￾cated that out-group hate was the dominant motivation for the 8-year-olds’ distributions of negative resources. Age differences were again significant—allocations to in￾group versus out-group: Mann-Whitney U = 417.00, p < .001, r = .40; allocations to in-group and neutral box ver￾sus 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 cor￾relation 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-year￾old 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

6 Buttelmann,Bobm member,and 13%and 35%of the items to the box.These The current study leaves some questions unanswered differences indicated an even larger gender gap in in- y,itis undand characteristics of control for .D- resources and avoid negative resources and that the chil Discussion dren's allocations would not result in any personal gains Our aim in the cu hether dy.we used fict ow an in-group biasnl we rav nd wanted to find out what motivations underlie in-group of our participants,future research should indlude real biased behavior among children.We developed a new outcomes.For instance,one could provide recipients with an endowment (of,e.g.candy)that may increase 5mnatebeteenpost and ain)as of group hate.Both age groups showed a clear in-group lly.th be different motivations that underlie the conception of bias in both domains of resources,positive and negative out-group hate:to absolutely harm the out-group or to the relative een the in-group relative to distir and out-group hate were able to serve as a behavioral the distinction between competitiveness and pure ham motivation (i.e.,in the allocation of positive resources). on a behavioral level may be a direction for future intergroup discrimination research. o-year whicl even str of the obtained findin was excluded as a potential source of this effect (ie in the allocation of negative resources),we found out-group societies.However.intragroup cooperation can sacrifice hate to be a behavioral motivation for inte oup collective efficiency if the aim is to harm other groups to criminati 8-year-on flict (Bohm Roc rely damaged by engagingin long-lasting inte harmed the out-group by giving the majority of negative conflicts.Given that our results suggest not only that in group love and out-group hate are independent of each box (ie ane but that group love emerges in human in-group p e motivati quences for one's own group constitute the foundation of humans'inherent prosocial nature.Children,and in par. in-group bias and discrimination,whereas the negative ticular boys.should be taught as early as prescho ol age groups ecom behavioral nd loyalty are valuable an t is intere in the lon ticular showed out-group hate.From an evolutionary tion at the same time. perspective,there are good reasons for why males are more prone em les to ngage in Author Contributions be reinforced through cultural processes.This gender gap is also consistent with other research findings that have indi mainly boys who show paroc Acknowledgments hat dif ences (ie..out-group hate)between boys and girls may at least partially,contribute to a gender gap in children's thank M.Pigors for valuable advice on technical implementa

6 Buttelmann, Böhm member, and 13% and 35% of the items to the box. These differences indicated an even larger gender gap in in￾group 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 alloca￾tion of positive and negative resources. Specifically, we wanted to find out what motivations underlie in-group￾biased 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 out￾group 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 out￾group 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 dis￾crimination 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 con￾clude that in-group love develops before out-group hate in human ontogeny. Accordingly, the positive conse￾quences 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 par￾ticular 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 prefer￾ences (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 chil￾dren’s allocations would not result in any personal gains or losses. Furthermore, in the current study, we used ficti￾tious 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 moti￾vation 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 far￾reaching. 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 in￾group love and out-group hate are independent of each other but also that in-group love emerges before out￾group hate in human development, it is possible to affect both of these motivations separately by building on humans’ inherent prosocial nature. Children, and in par￾ticular 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 deroga￾tion 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 manu￾script 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 implementa￾tion, the research group at the Center for Empirical Research in Economics and Behavioral Sciences for inspiring discussions, Downloaded from pss.sagepub.com by Cai Xing on February 13, 2014

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