Keywords

Social exclusion is a common experience in social life, and it begins in childhood. Persistent or prolonged experiences of exclusion in childhood are related to long-term negative consequences, such as depression, social withdrawal, and anxiety (Bierman, 2004; Rubin, Bukowski, & Parker, 2006). When children withdraw from social interactions and social relationships, a negative cycle ensues, because positive social experiences in childhood are important for healthy emotional wellbeing, academic success, and productive work experiences in adulthood (Buhs & Ladd, 2001; Coie, Terry, Lenox, & Lochman, 1995; DeRosier, Kupersmidt, & Patterson, 1994; Prinstein & Aikins, 2004). Most developmental research on interpersonal peer exclusion has documented how patterns of victimization and bullying behavior reflect individual differences in temperament, attachment, confidence, and social-cognitive skills like intention attribution (e.g., Gunnar, Sebanc, Tout, Donzella, & van Dulmen, 2003; Masten et al., 2009). For example, children who are extremely shy, fearful, and wary are more vulnerable to victimization, whereas children who are highly externalizing are at risk for becoming bullies (Hodges, Boivin, Vitaro, & Bukowski, 1999; Olweus, 1993; Rubin et al., 2006).

Recently, Killen, Mulvey, and Hitti (2013) differentiated interpersonal peer exclusion from intergroup social exclusion in childhood. This distinction has been well charted in social psychology research with adults (Abrams, Hogg, & Marques, 2005), but has only been extensively documented in the past decade from a developmental perspective. Intergroup social exclusion is a highly salient form of peer exclusion based on group membership, such as gender, race, ethnicity, sexual orientation, or culture (Killen & Rutland, 2011; Rutland, Killen, & Abrams, 2010). That is, there are times in children’s and adolescents’ lives when the source of exclusion lies with prejudicial attitudes about group membership rather than with individual differences in personality traits that contribute to negative interpersonal relationships. Prejudicial attitudes are often designed to maintain social hierarchies, status, and power, and are prevalent throughout childhood and into adulthood (Killen, Mulvey, & Hitti, 2015). Processes examined from an intergroup perspective include group identity, in-group bias, out-group threat, and stereotypic associations about traits assigned to members of groups (Dovidio, Glick, & Rudman, 2005).

One of the most compelling distinctions between interpersonal peer exclusion and intergroup social exclusion pertains to the relevant form of intervention to improve developmental outcomes. The causes of interpersonal social exclusion (e.g., aggression) are often exacerbated by the experience of exclusion, creating a cycle of victimization (Dodge et al., 2003; Ladd, 2006). Similarly, socially withdrawn children’s experiences of loneliness are often explained by their experiences of exclusion by peers (Boivin, Hymel, & Burkowski, 1995). For excluded children, even one stable best friendship results in better mental health in adulthood (Bagwell, Newcomb, & Bukowski, 1998). Through interventions, victimizers and victims can learn social skills, such as reading social cues better (victimizers) and being more confident (victims), gaining social competence and resilience (Bierman, 2004; Rubin et al., 2006).

By contrast, intervention programs for intergroup social exclusion are targeted at awareness for all children, and particularly for the high status groups that are often more likely to hold prejudicial attitudes (Abrams & Killen, 2014; Rutland & Killen, 2015). The percentage of children who are at risk for exclusion based on personality traits is approximately 10–15 %. By contrast, the percentage of children who are at risk for becoming the target of prejudicial attitudes can be much higher, depending on the type of prejudicial attitude that perpetuates intergroup exclusion. While research on interpersonal exclusion is extremely important for understanding individual differences in vulnerability to victimization, exclusion of a peer on the basis of personality (e.g., shyness) is different from exclusion of a peer on the basis of group membership (e.g., gender). Complementing research on interpersonal peer exclusion, research on intergroup social exclusion is designed to understand the origins of prejudice and the roles that group identity, group norms, and group dynamics play for fostering or inhibiting discrimination and social exclusion.

In this chapter, we focus primarily on intergroup social exclusion, given the extensive treatment of interpersonal peer exclusion that already exists in literature in both developmental and social psychology. Intergroup social exclusion involves processes different from those involved in interpersonal peer exclusion, but results in some of the same long-term negative developmental outcomes such as depression, distress, and anxiety (Brown, Bigler, & Chu, 2010; Fisher, Wallace, & Fenton, 2000). In fact, the urgency of research on intergroup social exclusion has been made clear by research on the negative outcomes of discrimination and bias, which reveals a host of physiological distress signals (Neblett, White, Philip, Nguyên, & Sellers, 2008; Seaton & Yip, 2009; Yip & Douglass, 2011).

Cultural beliefs about status, stereotypes based on group membership, and exclusive intergroup attitudes have been examined extensively in adult populations for more than 50 years (Dovidio et al., 2005; Dovidio, Hewstone, Glick, & Estes, 2010). Yet prejudice, stereotyping, and exclusion emerge in childhood and develop into adolescence (Killen et al., 2015). In fact, expectations about groups’ relative power and status are reflected in children’s peer interactions from as early as the preschool years (Bigler & Liben, 2006; Elenbaas & Killen, in press; Rutland et al., 2010). Intergroup social exclusion has been widely documented in countries around the world, and is disproportionally experienced by children and adolescents from cultural minority groups (Killen & Rutland, 2011; Møller & Tenenbaum, 2011; Nesdale, 2004; Verkuyten, 2008). As intergroup social exclusion emerges in childhood, it is essential to understand why, and under what circumstances, children and adolescents in countries around the world exclude peers on the basis of group membership.

One of the significant developmental processes that enables children and adults to be inclusive, rather than exclusive, is the emergence of conceptions of fairness, justice, and rights. That is, children’s moral concepts of fairness and equality are early-emerging (Killen & Smetana, 2015), and while children seek affiliation with in-groups, they also form notions of fair and equal treatment of others regardless of group membership. These moral concerns impact children’s and adolescents’ evaluations of social exclusion. Further, developing conceptions of discrimination and rights promote inclusion in development, and local and group norms can combat exclusion through promotion of tolerance and equal opportunity (Hitti & Killen, 2015; Horn & Szalach, 2009). Thus, in this chapter, we review not only how children perpetuate social exclusionary attitudes, but also how they challenge and resist such tendencies, concluding with the implications of this work for promoting equality throughout development.

Intergroup Social Exclusion in Childhood and Adolescence

Social group affiliations change across the lifespan as individuals experience different degrees of salience for their various group memberships, and vary by context as children and adolescents receive different messages about group affiliation (Edmonds & Killen, 2009; Yip, 2014). However, from an early age, children construct notions of groups’ relative status, and use stereotypes to justify excluding peers from lower-status groups. In this section, we review research on how children’s stereotypes and adherence to group norms bear on their decisions to exclude peers from groups, and review the complex roles of group identity and prejudice in social exclusion during development.

Stereotypes and Denial of Opportunity

Children’s use of stereotypes to determine who should or should not be included in social groups may deny peers who do not fit such stereotypes the opportunity to engage in group activities. For example, preschoolers have been shown to use gender stereotypes to determine whether a boy or a girl should be allowed to join a group of peers playing with dolls or playing with trucks (Killen, Pisacane, Lee-Kim, & Ardila-Rey, 2001; Theimer, Killen, & Stangor, 2001). Young children in these studies often referenced gender stereotypes about who would be better at the given activity to justify exclusion (e.g., “girls don’t like playing with trucks”). This first example illustrates how early stereotypes about individuals based on their group membership emerge. Beginning in early childhood, children start to exclude others who do not adhere to social expectations.

Over time, excluded children may be denied opportunities of increasing importance because of assumptions about who “fits” with a given group. For example, one recent study found that non-Arab-American adolescents made stereotypic assumptions that a group of Arab-American peers would choose new friends on the basis of ethnic match, even as they asserted that a non-Arab-American group would be inclusive, choosing new friends based on a match of hobbies and activity preferences and ignoring ethnicity (Hitti & Killen, 2015; see Fig. 1 for a depiction of stimuli used in this study). Further, adolescents who held stereotypes about Arab-Americans were less likely to opt to include an Arab-American peer into their own social group, demonstrating how negative messages about stigmatized social groups perpetuate exclusive attitudes and behaviors.

Fig. 1
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Ethnic peer groups as depicted in the female protocol, originally published in Hitti and Killen (2015: fig. 1) (reprinted by permission of the publisher), © 2010, Joan Tycko, illustrator

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Stereotypes about group similarities and differences, like these, are pervasive throughout childhood and adolescence. Related work has even shown that European-American children perceive two African-American peers with different hobbies to be more alike than two European-American peers with different hobbies (McGlothlin, Killen, & Edmonds, 2005). Thus, in addition to creating exclusive attitudes and barriers for friendships across group boundaries, stereotypes impact adolescents’ expectations for out-group members’ preferences and social behavior, leading to the perpetuation of misunderstanding and distrust.

Norms and Exclusion

In addition to stereotypic expectations about individuals based on their group membership, larger social norms and unique group norms influence children’s decisions about exclusion, particularly in later childhood and adolescence. For example, older children often expect negative outcomes for those who deviate from gender norms about appropriate activities for males and females. One recent study found that older children and early adolescents personally supported individuals’ decisions to challenge groups’ gender stereotypic activity preferences by suggesting that the group try a non-stereotypic activity (e.g., a girl in an all-girls group that always does ballet suggests that the group play football instead). However, they expected that individuals who advocated for such changes, especially boys who expressed interest in gender non-stereotypic activities (e.g., ballet), would not be well received by their groups, and would likely be excluded (Mulvey & Killen, 2015; see Fig. 2).

Fig. 2
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Likelihood of exclusion of the challenger for football and ballet, originally published in Mulvey and Killen (2015: fig. 4) (reprinted by permission of the publisher). ***p < .001

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Further illustrating how social hierarchies are established and enforced in development, adolescents have been found to judge both straight and gay peers who engage in gender non-conforming activities and appearance as less acceptable than gender conforming peers, and males, ranked higher on the gender hierarchy, rate other straight males who are gender-non-conforming as least acceptable (Horn, 2007). Likewise, older adolescents evaluate exclusion of peers due to sexual orientation as more acceptable than other forms of discrimination such as teasing, harassing, or assaulting a gay or lesbian peer, and are more likely to refer to social norms and personal choice in regard to exclusion of a sexual minority peer (Horn, 2006). Thus, exclusion of an individual because of nonconformity to social norms and expectations pertaining to their group membership is often perceived as legitimate. This demonstrates how older children and adolescents expect exclusion to be a consequence of non-adherence to social norms, emphasizing their increasing awareness that the threat of exclusion can be a social tool for promoting conformity.

Paralleling these findings, recent studies examining norms on a group level (rather than a societal level) have demonstrated that, while children often personally approve of an individual who advocates for fair resource distribution in a context of inequality between groups, they also expect that others would not like that individual as much as they would. For instance, one study found that preschoolers personally approved of a peer who went against their classroom norm of seeking to keep more toys for themselves by advocating for equal allocation, but thought that other members of the classroom would be less approving of that individual (Cooley & Killen, 2015). These same differential attributions have also been found in older children’s expectations about an after-school club’s opinion of an individual who advocated for equal allocation of money between clubs when the usual approach was to seek more for the in-group (Killen, Rutland, Abrams, Mulvey, & Hitti, 2013; Mulvey, Hitti, Rutland, Abrams, & Killen, 2014). Further, recent studies indicate that group status plays an important role in children’s expectations for how groups will respond to inequality. Under most circumstances, advantaged groups (with plentiful resources) are perceived to be less likely to take action to correct an inequality than are disadvantaged groups (Elenbaas & Killen, 2016).

In line with findings about the expected consequences of deviating from gender norms, these studies show that, from an early age, children expect that standing up to norms that exclude minority groups from opportunities and access to resources will not be easy, and will likely result in decreased support from the in-group. Together, this research reveals how, with age, children increasingly expect that groups will reject individuals who dissent from the prevailing social norms about status. Importantly, although children often personally support equality, they also recognize that voicing that opposition to the status quo may be untenable in light of dominant social hierarchies.

Social Identity and Prejudice

Interestingly, despite the strong influence of social norms and expectations on children’s decisions to exclude, several studies have shown that children who are members of groups ranked lower on the status hierarchy (e.g., often girls and racial/ethnic minority children) are less likely to view social exclusion to be acceptable than their male and racial/ethnic majority peers. Highlighting the importance of group identity in developing conceptions of exclusion and prejudice, these findings point to one of the ways in which the material consequences of reduced access to resources and opportunities directly shapes children’s support for equality and equal access.

With age, many adolescents in the USA, particularly those of African-American and Latino background, report increasing personal experiences with exclusion and discrimination perpetrated by teachers, peers , and strangers, with reports ranging from wrongful discipline in school to being hassled by store clerks to teasing and online harassment (Fisher et al., 2000; Rivas-Drake, Hughes, & Way, 2009; Umaña-Taylor, Tynes, Toomey, Williams, & Mitchell, 2015; Wong, Eccles, & Sameroff, 2003). Perhaps as a result of their personal experiences with prejudice and exclusion, several studies have revealed that older racial minority children and adolescents are less likely than their racial majority counterparts to view socially excluding a peer as acceptable, particularly in intimate situations like cross-race dating (Killen, Henning, Kelly, Crystal, & Ruck, 2007). Further, in later childhood, girls in many countries around the world have been found to be less accepting of exclusion of any kind than boys (Killen, Lee-Kim, McGlothlin, & Stangor, 2002; Killen & Stangor, 2001; Park & Killen, 2010). These findings suggest that membership in a traditionally excluded group (race, gender) can lead children to more negatively evaluate exclusion experienced by others.

Supporting this claim, research indicates that children from stigmatized groups are more aware of others’ racial stereotypes than children from non-stigmatized groups (McKown & Weinstein, 2003). Likewise, when evaluating instances of interethnic exclusion, early adolescents from ethnic minority backgrounds (both in the USA and other countries) have been found to attribute more positive emotions (e.g., pride) to ethnic out-group members who exclude an ethnic minority individual from a group than do early adolescents from ethnic majority backgrounds (Malti, Killen, & Gasser, 2012). These findings indicate that children whose social groups are the targets of habitual exclusion not only evaluate such behavior more negatively than their same-aged peers from majority group backgrounds, but they also assume that the excluding group feels proud of their biased actions.

Building on the research above concerning majority group children’s stereotypic assumptions about the similarity of minority group members, these findings suggest that minority group children often perceive hostile attitudes toward inclusion from majority groups (i.e., they believe that majority groups feel good about excluding ethnic out-group members). These perceptions further underscore the cycle of intergroup misunderstanding and cynicism about inclusion that begins in childhood and adolescence.

Importantly, however, the extent to which children and adolescents identify with their social group, beyond simply belonging to that group, influences their evaluations of other in-group members who exclude out-group peers . For instance, in a study testing the factors that contribute to social exclusion based on religious identity in peer, home, and community contexts, Jewish American and non-Jewish American adolescents who reported higher levels of identification with their culture were less inclusive than those who identified less with their culture (Brenick & Killen, 2014). This means that membership in a traditionally marginalized group is no guarantee of inclusive attitudes. Rather, children’s and adolescents’ level of identification with their social group, as well as experiences as members of that group, impacts their willingness to include out-group peers. More broadly, research has shown that whether or not children demonstrate prejudice toward members of out-groups depends on the strength of their identification with their group, whether or not the out-group is perceived as threatening, and whether they believe that showing prejudice is consistent with the norms of the in-group (Nesdale, Maass, Durkin, & Griffiths, 2005; Rutland, Cameron, Milne, & McGeorge, 2005).

Developmental Outcomes of Intergroup Social Exclusion

In addition to the social, cognitive, and emotional consequences of intergroup social exclusion described above, exclusive behavior based on group membership in childhood and adolescence perpetuates social hierarchies that restrict access to resources for disadvantaged groups. For example, a large body of research has documented the consequences of socioeconomic disparities, particularly on health and academic achievement (Bradley & Corwyn, 2002; Brooks-Gunn & Duncan, 1997; McLoyd, 1998; Orfield & Lee, 2005; Saegert et al., 2007; Shonkoff & Phillips, 2000; Yoshikawa, Aber, & Beardslee, 2012). Yet understanding how social inequalities originate and are maintained requires a focus on the social as well as the material aspects of inequality (Killen, Elenbaas, Rizzo, & Rutland, 2016).

The problems associated with disadvantage are not equally distributed across the population. Rather, children and adults in groups based on race, ethnicity, gender, and sexual orientation are disproportionally affected. Thus, exclusion pertains not only to differential access to resources, but also to a set of cultural beliefs about the “types” of people that are more esteemed, respected, and deserving of resources than others (Appiah, 2005; Ridgeway, 2014; Sen, 2009; Tajfel & Turner, 1979). Through reciprocal processes of disadvantage and stigmatization, excluded groups are further restricted from access to resources as stereotypes and biases perpetuate discrimination (Lott, 2002).

For example, though economic inequality affects children of all racial/ethnic backgrounds, approximately two-thirds of African-American, Latino, and Native American children live in low-income families, in contrast to approximately one-third of their European-American and Asian-American peers (Addy, Engelhardt, & Skinner, 2013). As a result of economic inequalities, more than two thirds of African-American and Latino students attend lower-income schools, compared with less than one third of Asian-American and European-American students (Orfield & Lee, 2005). Likewise, the more time young children spend in same-sex peer groups, the more they tend to endorse gender stereotypic attitudes and behaviors (Maccoby, 2002; Martin & Fabes, 2001). Gender stereotypic assumptions about girls’ abilities have detrimental impacts on their self-esteem, as well as academic motivation (Brown & Bigler, 2005; Halpern et al., 2011). And although both men and women are affected by gender stereotypes, in adulthood, women’s median income is lower than men’s on average, even when they have the same occupation and level of education (Saegert et al., 2007).

Children’s social experiences in peer groups , making decisions about inclusion and exclusion and resource distribution and access, are connected to the social inequalities of their surrounding environment. Research on exclusion in development that includes consideration of social status helps to explain part of the reproduction of power and privilege that perpetuates inequality, through a dual focus on the material consequences of social resource disparities as well as the norms and beliefs about power and status that reinforce existing social hierarchies.

While the research discussed thus far provides ample evidence of how children’s and adolescents’ biases, adherence to group norms, and discriminatory actions establish and maintain social hierarches throughout development, there is also evidence that reasoning about inclusion and equality emerges early in development and reflects concern for the fair treatment of peers (Killen & Smetana, 2015). In the next section, we outline how research in developmental science reveals that, as children develop social cognitive categories related to group identity and morality, and become aware of status hierarchies, in many cases they begin to argue for rectifying inequalities, drawing on their concerns for others’ welfare, rights to resources, and equal treatment (Elenbaas & Killen, in press; Killen et al., 2016).

Fairness and Inclusion in Childhood and Adolescence

As members of social groups, children often seek a balance between preserving group norms, equal and just treatment of others, adherence to societal norms, and expectations from both peers and parents. Children are not always subject to intergroup biases, rather, they reason about the legitimacy of social norms and exclusive attitudes (Killen, Rutland, et al., 2013). Just as children sometimes use stereotypes to condone exclusion, there are times when they reject discrimination in favor of inclusion and equality, drawing a balance between group affiliations and support of others’ rights to resources (Helwig, Ruck, & Peterson-Badali, 2014; Killen & Smetana, 2015). Through investigation of these dynamic processes, the immediate and long-term negative consequences of social exclusion on developmental outcomes can be reduced (Abrams & Killen, 2014).

Perceptions of Discrimination

Children’s ability to detect exclusion, prejudice, and discrimination in others’ actions increases with age. For instance, between early and middle childhood, children become increasingly aware of existing economic inequalities between racial groups (Bigler, Averhart, & Liben, 2003), and by middle childhood, children in the USA and in other countries spontaneously offer the example of unequal distribution of goods between groups when asked what kinds of behaviors constitute discrimination (Brown & Bigler, 2005; Verkuyten, Kinket, & van der Wielen, 1997). Further, in older childhood and adolescence, children increasingly perceive racial bias and discrimination in the US political system (Bigler, Arthur, Hughes, & Patterson, 2008), and recognize that racial minority groups are more likely to be the targets of institutional discrimination than racial majority groups (Brown, Mistry, & Bigler, 2007). Thus, older adolescents more readily identify the institutionalized biases of their social environment, recognizing that people may act on their stereotypes and biases, and that historically marginalized groups are often the targets of exclusion.

Similarly, with age, children draw progressively stronger connections between their own daily experiences and overarching social biases. For instance, when evaluating the exclusion of an African-American child from a group of European-American peers, African-American children and adolescents have been found to reason about the wrongfulness of this action in the larger context of society by elaborating on the negative consequences of discrimination (Killen et al., 2002). These findings illustrate how, between middle childhood and adolescence, children begin to connect their own everyday experiences of exclusion with larger, systemic inequalities in their social environment. Notably, children are especially likely to perceive gender or racial discrimination in familiar contexts if the potential perpetrators have a history of biased behavior in line with their current actions. That is, children are more likely to recognize someone’s behavior as discriminatory when they have converging evidence of that individuals’ past behavior or present prejudicial attitudes (Brown, 2006; Brown & Bigler, 2004).

In a recent series of studies on resource allocation and social inequalities, Elenbaas, Killen, and colleagues examined how children allocate necessary resources to groups when the same resources have been allocated unequally between racial groups in the past (Elenbaas & Killen, in press; Elenbaas, Rizzo, Cooley, & Killen, 2015; Killen et al., 2016). The aim of this work was to examine children’s responses to social inequality, testing how their affiliations with racial in-groups and out-groups interact with their support for equality and fair distribution to influence resource allocation decisions. In one study, children’s responses to an inequality of educational resources changed with age, as children considered the implications of restricting access to this important resource (Elenbaas et al., 2015). In this study, 5–6 year-olds negatively evaluated an inequality of school supplies that put their racial in-group at a disadvantage, but evaluated the same disparity neutrally when it put their racial out-group at a disadvantage. By contrast, 10–11 year-olds did not differentiate whether it was their in-group or their out-group receiving fewer resources. Older children in this study evaluated social inequality negatively, took action to correct it when they had the opportunity to allocate resources, and reasoned about the importance of equal access and correcting past inequalities, regardless of whether it was their in-group or their out-group that had received fewer resources.

Along these same lines, research has also shown that, with age, older children and adolescents determining whether to include a boy or girl in a gender stereotypic activity include children who do not match the gender stereotype when both potential playmates are equally skilled at the game and equally interested in joining (Killen & Stangor, 2001). This demonstrates a concern for fairness and inclusion in older children that relates to providing opportunities for under-represented groups. Together these and other findings indicate that, with age, children not only recognize restriction of access to resources for certain social groups as discrimination, but also take action to ensure equal access when they have the chance to allocate resources and opportunities. Thus, when children and adolescents have direct evidence of discrimination, they often seek to rectify past disparities, even if it means that their own group receives less of a valued resource. These findings reveal the strength of children’s developing concern for others’ wellbeing, and highlight the developmental process whereby children formulate an understanding about social inequalities.

Support of Rights

In addition to detecting discrimination, research indicates that, with age, children and adolescents are increasingly able to reason about their own and others’ rights to resources. Recent studies indicate that, from as early as 6 years of age, children recognize that restricting groups’ access to resources that are needed to avoid harm (e.g., medicine) has negative implications for individuals’ welfare (Rizzo, Elenbaas, Cooley, & Killen, in press). It is not until early adolescence, however, that children begin to reason about their own and other’s equal rights to access societal resources (Helwig et al., 2014; Peterson-Badali & Ruck, 2008; Ruck, Tenenbaum, & Willenberg, 2011).

For example, research on children’s conceptions of nurturance rights indicates that, by about 10 years of age, children support their own and others’ rights to quality education and medical care (Peterson-Badali, Morine, Ruck, & Slonim, 2004). One study found that even young children negatively judged a law prohibiting certain groups of children from receiving the same type of education as their peers, or prohibiting doctors from treating poor people (Helwig & Jasiobedzka, 2001). Endorsing others’ rights to access resources like these (i.e., education and medical care) is not the same, however, as actively reasoning about these issues as entitlements, rather than privileges that could be taken away. Reasoning along these lines emerges and develops in adolescence (Ruck, Keating, Abramovitch, & Koegl, 1998). Interestingly, one study found that adolescents were more likely than younger and older children to reject a hypothetical governmental decision to exclude children of one race from attending school, on the basis of their reasoning that all children deserve education (Killen et al., 2002).

Notably, research indicates that, in many cases, issues of individual rights are not subordinated to community norms or obedience to authority, even in cultures traditionally characterized by high adherence to group norms or hierarchy (Helwig et al., 2014). Rather, individual rights and fairness are important to adults and children in diverse cultural settings, and reasoning based on rights and autonomy increases with age in children around the world (Elenbaas & Killen, in press). Together, these findings indicate that, in later childhood and adolescence, children’s negative evaluations of resource inequality begin to incorporate notions of larger-level disparities apparent in their everyday lives, expanding to an emerging recognition of rights violations for certain groups. This suggests that, although their personal experience with acquiring access to resources like education and medical care is second hand, they often deem that these social resources should be fairly distributed.

Supporting this claim, recent research indicates that children’s awareness of overarching societal disparities between groups predicts their responses to group-based resource inequalities (Elenbaas & Killen, in press). For example, one recent study found that, with age, both European-American and African-American children gained increasing awareness of economic disparities between African-Americans and European-Americans. When these same children witnessed an inequality of medical supplies between hospitals serving these two racial groups, they evaluated the disparity more negatively with age. Many older children also reasoned about groups’ rights to adequate medical care, demonstrating early recognition of this issue as rights-related. Increasing awareness of overarching economic inequalities combined with increasingly negative moral judgments of the resource disparity explained age-related increases in children’s endorsement of actions taken to attenuate the inequality by giving more to a hospital serving African-Americans that had received less in the past. That is, increasing sophistication in children’s moral judgments and increasing social knowledge about groups were both important contributors to older children’s desire to rectify resource inequalities. Together this research reveals that, beyond in-group affiliations, children’s awareness of historical patterns of unequal access to important resources impacts their conceptions of group’s rights in the present and their support of actions taken to correct past inequalities and current disparities.

Intergroup Contact and Inclusion

In addition to age-related increases in recognition of discrimination and support for groups’ rights to resource access, considerable research in developmental science has focused on the social and contextual variables that support children of all ages in developing inclusive and tolerant attitudes and behaviors. In addition to reducing prejudice overall (Tropp & Prenovost, 2008), greater opportunities for contact with members of a relevant social out-group can lead to more proactive attitudes about inclusion and fairness for both majority and minority status children and adolescents.

Broadly, school diversity is a strong predictor of positive learning outcomes, heightened civic engagement, and preparation of students for a diverse workforce (Orfield & Lee, 2005). Research also indicates that racial/ethnic minority students feel safer, less harassed, and less lonely, and report higher self-worth the more racially/ethnically diverse their classrooms are (Juvonen, Nishina, & Graham, 2006). Thus, positive and cooperative interaction with members of other social groups improves not only immediate interpersonal relations, but prepares children for diverse workplaces and adult social spaces.

More specifically, both racial minority and majority children report more inclusive attitudes in diverse schools. For example, whereas younger European-American children in racially homogeneous schools demonstrate implicit negative assumptions about racial minority peers in ambiguous social interactions, children at the same age, in the same school district, enrolled in racially diverse schools demonstrate no such implicit racial biases (McGlothlin et al., 2005; McGlothlin & Killen, 2006). Further, evidence from several countries around the world indicates that racial/ethnic majority children who report greater numbers of friends from racial/ethnic minority backgrounds (i.e., cross-group friendships) experience more positive intergroup relations over time (Aboud, Mendelson, & Purdy, 2003; Feddes, Noack, & Rutland, 2009). Likewise, racial minority adolescents who report greater contact with out-group peers are more likely than their peers reporting little intergroup contact to rate intergroup exclusion as more wrong and to assert that they would intervene if they witnessed exclusion (Ruck, Park, Killen, & Crystal, 2011).

In regard to reasoning about groups’ access to resources, some studies support age-related increases in reasoning about fairness and equality among children attending diverse schools (Elenbaas et al., 2015; Killen et al., 2016), suggesting that school racial diversity may be an important factor in the decision to rectify resource inequalities between groups. Although direct comparisons with samples from racially homogeneous schools are not yet available, it is possible that conceptions of fairness in the context of resource inequality, like reasoning about peer-based inclusion and exclusion, are impacted by environmental diversity and children’s opportunities to interact with others from different backgrounds.

In addition to providing opportunities for friendship with peers of other social groups, research also supports the conclusion that more immediate level school and peer norms play an important role in children’s judgments about exclusion. For example, adolescents attending schools with safe school practices regarding sexual orientation (e.g., policies, professional development) have been found to evaluate exclusion on the basis of sexual orientation as more wrong and to use more moral reasoning in justifying their judgments than adolescents attending schools without such practices (Horn & Szalach, 2009). Research also indicates that preschoolers who use gender stereotypes to determine who should be able to join a peer group activity are willing to change their decision to focus on fairness and inclusion of underrepresented groups when the fairness of turn-taking is suggested by an adult (Killen et al., 2001). Thus, adults can have a positive impact on children’s inclusive attitudes by establishing norms about inclusion on an institutional level.

More locally, children are more likely to demonstrate prejudice toward out-group members if they believe that such actions are condoned by their peer in-group (Nesdale et al., 2005; Rutland et al., 2005). Yet conversely, adolescents placed in social groups with stated goals of inclusivity (seeking to include others who are “different” from them) have been shown to be more inclusive of ethnic out-group peers than adolescents placed in similar groups with exclusive norms (i.e., preferences for those who are “similar to them”; Hitti & Killen, 2015).

These findings show how norms and expectations are at work in children’s decisions to include and exclude, from larger community norms of diversity, to local school norms of acceptance, to unique peer group practices. Adults and children alike can promote inclusion by facilitating intergroup contact and understanding. Beyond simply bringing groups together, opportunities for close friendships across group boundaries, adult-instigated policies of tolerance, and peer group-generated norms of inclusiveness have all been shown to have positive and wide-ranging effects for reducing stereotypes and promoting equality in development.

Conclusion

Children’s biases, adherence to group norms, and discriminatory actions contribute to the cycle of social exclusion that begins early in development. Yet children also display a concern for others’ welfare and equal treatment in situations that reflect diversity of group membership based on race, ethnicity, gender, culture, and sexual orientation. In fact, research indicates that these different orientations coexist within individuals throughout development. Thus, beyond consideration of the negative outcomes of exclusion, research on this multifaceted issue includes consideration of the norms and beliefs about status that reinforce existing social hierarchies. Social experiences in childhood can set the stage for adult cognition and behavior. Thus, the importance of a developmental perspective on social exclusion lies in its capacity to identify the psychological underpinnings of inequality and diminish the negative consequences of social exclusion for children and adults.

While intergroup social exclusion has sources that are distinct from the causes of interpersonal peer exclusion, some of the long-term negative consequences are the same. Moreover, there are situations in which intergroup exclusion can create problems with interpersonal relationships. For example, children who are persistently excluded because of their religion may develop negative personality dispositions, which may result in an inability to successfully form peer friendships. Conversely, children who are at risk for externalizing behavior, such as aggression, may create an exaggerated perception of out-group threat if they hold prejudicial or hostile attitudes towards others. Future research should more closely examine the potential intersections of these two forms of exclusion (i.e., intergroup vs. interpersonal).

While the consequences of exclusion and inequality are evident in the physical, cognitive, and social risks associated with group-based disparities, the origins of thinking about status and stigma are often less apparent. In this way, developmental science makes a vital contribution to understanding why and how social exclusion and social inequality persist and grow. Understanding exclusion in development, taking into consideration children’s understanding of social status, provides a window into early understanding of group dynamics, intergroup biases, and exclusive attitudes and behaviors.

As reviewed in this chapter, in some social contexts, and at particular periods in development, group identity becomes quite salient, leading children to use stereotypic expectations to guide their inclusive or exclusive attitudes towards peers. Everyday choices about restricting access to peer groups, opportunities, and resources reflect the social hierarchies of children’s worlds. These are no less damaging than the biases and discriminatory behaviors that permeate adult social relations. In fact, social exclusion of peers on the basis of group memberships like gender or race is already pervasive in childhood and adolescence, and reflects children’s developing biases, stereotypes, and beliefs about status.

Yet, as members of social groups, children often seek a balance between preserving group norms, equal and just treatment of others, adherence to societal norms, and expectations from both peers and parents. In fact, with age, children weigh stereotypes and motives to ensure fairness, consider in-group versus out-group status and identity, balance adherence to social norms with promotion of inclusion and equality, and consider rights as well as the consequences of deviating from exclusive or unequal norms. As children reflect on their experiences, considerations of fairness and equality predominate. With age, children demonstrate concern for rectifying social inequalities and challenging group norms that are exclusive or unfair.

As biases are often deeply entrenched by adulthood, understanding children’s perspectives on exclusion and inequality provides direction areas for intervention efforts in childhood. As the research in this chapter reveals, children demonstrate willingness to include out-group members in their social groups, detect discrimination, reason about others’ rights to resources, and rectify an unequal status quo. As they enter adolescence, children are afforded greater opportunity to exercise their willingness to enact social change. Fortunately, research also points to ways in which adults can structure children’s social environments to promote positive intergroup attitudes and inclusive behavior during this time, through co-construction of intergroup contact, inclusive social norms, and reasoning about equality and justice. These factors, and others, can positively impact children’s and adolescents’ views about exclusion and resource access, highlighting the significant role of social experience in the development of children’s orientations toward fairness.