In-group favoritism, sometimes known as in-group–out-group bias, in-group bias, or intergroup bias, is a pattern of favoring members of one's in-group over out-group members. This can be expressed in evaluation of others, in allocation of resources, and in many other ways.
This interaction has been researched by many psychologists and linked to many theories related to group conflict and prejudice. The phenomenon is primarily viewed from a social psychology standpoint. Two prominent theoretical approaches to the phenomenon of in-group favoritism are realistic conflict theory and social identity theory. Realistic conflict theory proposes that intergroup competition, and sometimes intergroup conflict, arises when two groups have opposing claims to scarce resources. In contrast, social identity theory posits a psychological drive for positively distinct social identities as the general root cause of in-group favoring behavior.
Origins of the research tradition
In 1906, the sociologist William Sumner posited that humans are a species that join together in groups by their very nature. However, he also maintained that humans had an innate tendency to favor their own group over others, proclaiming how "each group nourishes its own pride and vanity, boasts itself superior, exists in its own divinities, and looks with contempt on outsiders" (p. 13). This is seen on the group level with ingroup–outgroup bias. When experienced in larger groups such as tribes, ethnic groups, or nations, it is referred to as ethnocentrism.
Realistic conflict theory (or realistic group conflict) posits that competition between groups for resources is the cause of in-group bias and the corresponding negative treatment of members of the out-group. Muzafer Sherif's Robbers Cave Experiment is the most widely known demonstration of realistic conflict theory. In this experiment, 22 eleven-year-old boys with similar backgrounds were studied in a mock summer camp situation. The boys were divided into two equal groups and encouraged to bond, and then the researchers introduced a series of competitive activities in which the groups were pitted against one another. Hostility and out-group negativity ensued. Researchers then attempted to reverse the hostility by engaging the boys in situations of mutual interdependence, an effort which eventually resulted in relative harmony between the two groups. This study demonstrated that, regardless of two groups' similarity, group members will behave viciously toward the out-group when competing for limited resources.
According to Social identity theory, one of the key determinants of group biases is the need to improve self-esteem. The desire to view one's self positively is transferred onto the group, creating a tendency to view one's own group in a positive light, and by comparison, outside groups in a negative light. That is, individuals will find a reason, no matter how insignificant, to prove to themselves why their own group is superior. This phenomenon was pioneered and studied most extensively by Henri Tajfel, a British social psychologist who looked at the psychological root of in-group/out-group bias. To study this in the lab, Tajfel and colleagues created what are now known as minimal groups (see minimal group paradigm), which occur when "complete strangers are formed into groups using the most trivial criteria imaginable". In Tajfel's studies, participants were split into groups by flipping a coin, and each group then was told to appreciate a certain style of painting none of the participants were familiar with when the experiment began. What Tajfel and his colleagues discovered was that—regardless of the facts that a) participants did not know each other, b) their groups were completely meaningless, and c) none of the participants had any inclination as to which "style" they like better—participants almost always "liked the members of their own group better and they rated the members of their in-group as more likely to have pleasant personalities". By having a more positive impression of individuals in the in-group, individuals are able to boost their own self-esteem as members of that group.
Robert Cialdini and his research team looked at the number of university T-shirts being worn on college campuses following either a win or loss at the football game. They found that the Monday after a win, there were more T-shirts being worn, on average, than following a loss.
In another set of studies, done in the 1980s by Jennifer Crocker and colleagues, self-esteem was studied using minimal group processes in which it was shown that individuals with high self-esteem who suffer a threat to the self-concept exhibit greater ingroup biases than people with low self-esteem who suffer a threat to the self-concept. While some studies have supported this notion of a negative correlation between self-esteem and in-group bias, other researchers have found that individuals with low self-esteem have a higher prejudice to both in-group and out-group members. Some studies have even shown that high-self-esteem groups showed a greater prejudice than did lower self-esteem groups. This research may suggest that there is an alternative explanation and additional reasoning as to the relationship between self-esteem and in-group/out-group biases. Alternatively, it is possible that researchers have used the wrong sort of self-esteem measures to test the link between self-esteem and in-group bias (global personal self-esteem rather than specific social self-esteem).
Biological basis as an effect of oxytocin
In a meta-analysis and review of the effect of oxytocin on social behavior done by Carsten De Dreu, the research reviewed shows that oxytocin enables the development of trust, specifically towards individuals with similar characteristics - categorised as ‘in-group’ members - promoting cooperation with and favoritism towards such individuals. This bias of oxytocin-induced goodwill towards those with features and characteristics perceived to be similar may have evolved as a biological basis for sustaining in-group cooperation and protection, fitting with the Darwinian insight that acts of self-sacrifice and cooperation contribute to the functioning of the group and hence improve the odd of survival for members of said group.
Race can be used as an example of in-group and out-group tendencies because society often categorizes individuals into groups based on race (Caucasian, African American, Latino, etc.). One study that examined race and empathy found that participants receiving nasally administered oxytocin had stronger reactions to pictures of in-group members making pained faces than to pictures of out-group members with the same expression. This shows that oxytocin may be implicated in our ability to empathize with individuals of different races, with individuals of one race potentially biased towards help individuals of the same race than individuals of another race when they are experiencing pain.
Oxytocin has also been implicated in lying when lying would prove beneficial to other in-group members. In a study where such a relationship was examined, it was found that when individuals were administered oxytocin, rates of dishonesty in the participants’ responses increased for their in-group members when a beneficial outcome for their group was expected. Both of these examples show the tendency to act in ways that benefit people with which one feels is part of their social group, or in-group.
Self-Identity and Social Identity
As noted in two recent theoretical reviews, the theoretical basis for the inclusion of self-identity in the theories of reasoned action and planned behavior has many similarities to social identity theory  and its extension, self-categorization theory. According to social identity theory, an important component of the self-concept is derived from memberships in social groups and categories. When people define and evaluate themselves in terms of a self-inclusive social category (e.g. a sex, class, team) two processes come into play : (1) categorization, which perceptually accentuates differences between in-group and out-group, and similarities among in-group members (including self) on stereotypical dimensions; and (2) self-enhancement which, because the self-concept is defined in terms of group membership, seeks behaviorally and perceptually to favor the in-group over the out-group. Social identities are cognitively represented as group prototypes that describe and prescribe beliefs, attitudes, feelings and behaviors that optimize a balance between minimization of in-group differences and maximization of intergroup differences.
More specifically, according to social identity theory, there is a continuum between personal and social identity shifts along this continuum determine the extent to which group-related or personal characteristics influence a person’s feelings and actions. If a particular social identity is a salient basis for self-conception, then the self is assimilated to the perceived in-group prototype which can be thought of as a set of perceived in-group norms such that self-perception, beliefs, attitudes, feelings and behaviours are defined in terms of the group prototype. Thus, social identities should influence behaviour through the mediating role of group norms. People will be more likely to engage in a particular behaviour if it is in accord with the norms of a behaviourally relevant group membership, particularly if the identity is a salient basis for self-definition. If the group membership is not salient, then people’s behaviour and feelings should be in accord with their own personal and idiosyncratic characteristics rather than group norms.
On the other hand, the self-identity theory poses that the self is often a reflection of expected norms and practices in the role that the person places him/herself in. At the center of it is the proposition that the self is made up of multi-faceted and differentiated components that exist in an organized manner for the sake of filling in roles in society. People are able to create an identity for themselves only through talking to others, and often what roles they are taking on differ from one group to another. These differing roles and positions people is a result of their interactions with others and are called role identities. Role identities may be self-realized or facts like being a mother, a social worker, or a blood donor. Role identities lead people to act in certain ways due to assumed expectations for the roles. Because there is satisfaction in complying with expectations of the role, there is often distress behind an inability to appear congruent to one’s identity as defined by societal norms. There is also an existing hierarchy of importance for roles that individuals take on, and according to the hierarchical standing of roles, people become more representative of roles that stand higher hierarchically, according to them.
Identity salience, the likelihood of role identities being invoked in different situations, is the result of role identities being placed hierarchically in different orders from person to person. People who hold same roles may act differently because some roles are valued over others. For example, a working mother may have less time to spend with her child as opposed to a mother that doesn’t work. Behaviors are reflective of the identities that are held higher hierarchically by people, so people act out in self-worth and self-meaning according to these hierarchies. Someone who holds the identity of being a psychologist higher than the identity of being a linguist will find that while he/she may become competitive when meeting another person that is better at psychology than he/she, this individual won’t care when in contact with someone who is much better at being a linguist than he/she. In a similar way, social relationships are influenced by this salience. Self identity often places individuals in social contexts and a commitment to the role within that context becomes a big part of perpetrating the idea of self. It also finds people relating more to others that hold similar role identities at the top of their hierarchies.
Because people have self-concepts that are derived from a role they define for themselves within the context of a group, when staying within their roles, intergroup similarities are accentuated while intergroup differences are diminished. In an attempt to assimilate oneself according to the tendencies of a group, often people reconfigure their intragroup representations or identities. Certain prototypes form about these groups that reaffirms a rule by which members of the group are encouraged to follow. Shared information and views are more often discussed than novel and unshared information within a group, therefore a norm is established where the majority views are perpetuated and others silenced. This norm is fluid and changing according to different contexts, but those within the group are want to keep up with the majority views in all matters have keep an active role in affirming the views of the in-group in contest to out-groups.
Versus out-group negativity
Social psychologists have long made the distinction between ingroup favouritism and outgroup negativity, where outgroup negativity is the act of punishing or placing burdens upon the outgroup. Indeed, a significant body of research exists that attempts to identify the relationship between ingroup favouritism and outgroup negativity, as well as conditions that will lead to outgroup negativity. For example, Struch and Schwartz found support for the predictions of belief congruence theory. The belief congruence theory concerns itself with the degree of similarity in beliefs, attitudes, and values perceived to exist between individuals. This theory also states that dissimilarity increases negative orientations towards others. When applied to racial discrimination, the belief congruence theory argues that the perceived dissimilarity of beliefs has more of an impact on racial discrimination than does race itself.
Oxytocin is not only correlated with the preferences of individuals to associate with members of their own group, but it is also evident during conflicts between members of different groups. During conflict, individuals receiving nasally administered oxytocin demonstrate more frequent defense-motivated responses toward in-group members than out-group members. Further, oxytocin was correlated with participant desire to protect vulnerable in-group members, despite that individual’s attachment to the conflict. Similarly, it has been demonstrated that when oxytocin is administered, individuals alter their subjective preferences in order to align with in-group ideals over out-group ideals. These studies demonstrate that oxytocin is associated with intergroup dynamics.
Further, oxytocin influences the responses of individuals in a particular group to those of another group. The in-group bias is evident in smaller groups; however, it can also be extended to groups as large as one’s entire country leading toward a tendency of strong national zeal. A study done in the Netherlands showed that oxytocin increased the in-group favoritism of their nation while decreasing acceptance of members of other ethnicities and foreigners. People also show more affection for their country’s flag while remaining indifferent to other cultural objects when exposed to oxytocin. It has thus been hypothesized that this hormone may be a factor in xenophobic tendencies secondary to this effect. Thus, oxytocin appears to affect individuals at an international level where the in-group becomes a specific "home" country and the out-group grows to include all other countries.
Cross-cultural studies have found that in-group derogation, the tendency to criticize members of one's own group or culture more harshly than members of outside groups, is more common among members of disadvantaged and minority groups than among members of the majority or dominant group. According to psychology professor Christine Ma-Kellams et al. (2011), system justification theory seeks to explain why "minorities sometimes endorse system-justifying views of their group". They said their research into in-group favoritism and derogation partially supported this theory, but that the theory failed to address all of the nuances.
Ma-Kellams et al. also found that, compared to individualist cultures, people from collectivist cultures, such as East Asian cultures, tended to judge their own group members less favorably than they judged outsiders, whereas people from individualist cultures were inclined to judge members of their own group more favorably than they judged outsiders. Social identity theory and Freudian theorists explain in-group derogation as the result of a negative self-image, which they believe is then extended to the group. Ma-Kellams et al. theorized that "ingroup derogation may be more culturally normative and less troubling for East Asians" as evidenced by the fact that East Asians were also likely to report high levels of positive affect (emotion) towards members of their in-group, demonstrating ambivalence towards the unfavorable characteristics they had acknowledged about their in-group. According to Ma-Kellam et al., culturally-ingrained attitudes and beliefs, rather than low self-esteem, may play a role in collectivist cultures' in-group derogation due to their ability to tolerate holding seemingly contradictory views.
- Aronson, E., Wilson, T. D., & Akert, R. (2010). Social psychology. 7th ed. Upper Saddle River: Prentice Hall.
- Taylor, Donald M.; Doria, Janet R. (April 1981). "Self-serving and group-serving bias in attribution". Journal of Social Psychology. 113 (2): 201–211. doi:10.1080/00224545.1981.9924371. ISSN 0022-4545.
- Sumner, William Graham. (1906). Folkways: A Study of the Social Importance of Usages, Manners, Customs, Mores, and Morals. Boston, MA: Ginn.
- Billig, Michael; Tajfel, Henri (1973-01-01). "Social categorization and similarity in intergroup behaviour". European Journal of Social Psychology. 3 (1): 27–52. doi:10.1002/ejsp.2420030103. ISSN 1099-0992.
- Cialdini, Robert B.; Borden, Richard J.; Thorne, Avril; Walker, Marcus Randall; Freeman, Stephen; Sloan, Lloyd Reynolds (1974). "Basking in Reflected Glory: Three (Football) Field Studies". Journal of Personality and Social Psychology. 34 (3): 366–375. doi:10.1037/0022-35188.8.131.526.
- Crocker, Jennifer; Thompson, Leigh L.; McGraw, Kathleen M.; Ingerman, Cindy (May 1987). "Downward Comparison, Prejudice, and Evaluations of Others: Effects of Self-Esteem and Threat". Journal of Personality and Social Psychology. 52 (5): 907–916. doi:10.1037/0022-35184.108.40.2067. ISSN 0022-3514.
- Abrams, Dominic; Hogg, Michael A. (1988). "Comments on the motivational status of self-esteem in social identity and intergroup discrimination". European Journal of Social Psychology. 18 (4): 317–334. doi:10.1002/ejsp.2420180403.
- Sachdev, Itesh; Bourhis, Richard Y. (September 1987). "Status differentials and intergroup behaviour". European Journal of Social Psychology. 17 (3): 277–293. doi:10.1002/ejsp.2420170304.
- Rubin, Mark; Hewstone, Miles (February 1998). "Social Identity Theory's Self-Esteem Hypothesis: A Review and Some Suggestions for Clarification". Personality and Social Psychology Review. 2 (1): 40–62. doi:10.1207/s15327957pspr0201_3. PMID 15647150.
- De Dreu, Carsten K.W. (2012). "Oxytocin modulates cooperation within and competition between groups: An integrative review and research agenda". Hormones and Behavior. 61 (3): 419–428. doi:10.1016/j.yhbeh.2011.12.009. ISSN 0018-506X.
- Sheng F, Liu Y, Zhou B, Zhou W, Han S (February 2013). "Oxytocin modulates the racial bias in neural responses to others' suffering". Biological Psychology. 92 (2): 380–6. doi:10.1016/j.biopsycho.2012.11.018. PMID 23246533.
- Shalvi S, De Dreu CK (April 2014). "Oxytocin promotes group-serving dishonesty". Proceedings of the National Academy of Sciences of the United States of America. 111 (15): 5503–7. doi:10.1073/pnas.1400724111. PMID 24706799.
- Hogg, Michael A.; Terry, Deborah J.; White, Katherine M. (1995-01-01). "A Tale of Two Theories: A Critical Comparison of Identity Theory with Social Identity Theory". Social Psychology Quarterly. 58 (4): 255–269. doi:10.2307/2787127.
- Tajfel, Henri (1974-04-01). "Social identity and intergroup behaviour". Social Science Information. 13 (2): 65–93. doi:10.1177/053901847401300204. ISSN 0539-0184.
- Turner, John C. (1985). Advances in Group Processes: Theory and Research, Vol.2. Greenwichm, CT: JAI. pp. 77–122.
- Tajfel, Henri, John C. Turner (1979). The Social Psychology of Intergroup Relations. Brooks-Cole: Brooks-Cole. pp. 33–47.
- Stryker, Sheldon; Richard T. Serpe (1982). Personality, Roles, and Social Behavior. New York: Springer-Verlag. pp. 188–218.
- Nuttbrock, Larry; Patricia Freudiger (1991). Social Psychology Quarterly. pp. 146–157.
- Callero, Peter (1985). Social Psychology Quarterly 48. pp. 203–215.
- Tajfel, Henri (1959). British Journal of Psychology 50. pp. 16–29.
- Larson, J. R., Jr., Foster-Fishman, P. G., & Keys, C. B. (1994). Journal of Personality and Social Psychology. pp. 446–461.
- Tajfel, H., & Turner, J. C. (1979). "An integrative theory of intergroup conflict". In W. G. Austin & S. Worchel (Eds.), The social psychology of intergroup relations (pp. 33–47). Monterey, CA: Brooks/Cole
- Bourhis, R. Y.; Gagnon, A. (2001). Brown, R.; Gaertner, S. L., eds. "Social Orientations in the Minimal Group Paradigm". Blackwell Handbook of Social Psychology: Intergroup processes. 3 (1): 133–152. doi:10.1002/9780470693421.ch7.
- Mummendey, A.; Otten, S. (2001). Brown, R.; Gaertner, S. L., eds. "Aversive Discrimination". Blackwell Handbook of Social Psychology: Intergroup processes. 3 (1): 112–132.
- Turner, J. C.; Reynolds, K. H. (2001). Brown, R.; Gaertner, S. L., eds. "The Social Identity Perspective in Intergroup Relations: Theories, Themes, and Controversies". Blackwell Handbook of Social Psychology: Intergroup processes. 3 (1): 133–152. doi:10.1002/9780470693421.ch7.
- Struch, Naomi; Schwartz, Shalom H. (March 1989). "Intergroup Aggression: Its Predictors and Distinctness From In-Group Bias". Journal of Personality and Social Psychology. 56 (3): 364–373. doi:10.1037/0022-35220.127.116.114.
- West, Jeremy. "Racial Bias in Police Investigations" (PDF).
- Depew, Briggs; Eren, Ozkan; Mocan, Naci (2016-02-01). "Judges, Juveniles and In-group Bias". National Bureau of Economic Research.
- De Dreu CK, Shalvi S, Greer LL, Van Kleef GA, Handgraaf MJ (2012). "Oxytocin motivates non-cooperation in intergroup conflict to protect vulnerable in-group members". PloS One. 7 (11): e46751. doi:10.1371/journal.pone.0046751. PMC . PMID 23144787.
- Stallen M, De Dreu CK, Shalvi S, Smidts A, Sanfey AG (2012). "The herding hormone: oxytocin stimulates in-group conformity". Psychological Science. 23 (11): 1288–92. doi:10.1177/0956797612446026. PMID 22991128.
- De Dreu CK, Greer LL, Van Kleef GA, Shalvi S, Handgraaf MJ (January 2011). "Oxytocin promotes human ethnocentrism". Proceedings of the National Academy of Sciences of the United States of America. 108 (4): 1262–6. doi:10.1073/pnas.1015316108. PMC . PMID 21220339.
- Ma X, Luo L, Geng Y, Zhao W, Zhang Q, Kendrick KM (2014). "Oxytocin increases liking for a country's people and national flag but not for other cultural symbols or consumer products". Frontiers in Behavioral Neuroscience. 8: 266. doi:10.3389/fnbeh.2014.00266. PMC . PMID 25140135.
- Ma-Kellams, Christine; Spencer-Rodgers, Julie; Peng, Kaiping (2011-01-01). "I Am Against Us? Unpacking Cultural Differences in Ingroup Favoritism via Dialecticism". Personality and Social Psychology Bulletin. 37 (1): 15–27. doi:10.1177/0146167210388193. ISSN 0146-1672. PMID 21084525.