[6] Lastly, researchers 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.
Sherif concluded from this experiment that negative attitudes toward out-groups arise when groups compete for limited resources.
[6] However, he also theorized that inter-group frictions could be reduced and positive relations created,[6] but only in the presence of an overarching goal, which could only be achieved with the two groups' cooperation.
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.
[1] 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.
[13] 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 odds of survival for members of said group.
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.
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.
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.
Various neural correlates are impacted by group membership, which can shed light on the development of biases toward in-group members.
The brain plays a critical role in how individuals classify themselves and others into groups based on personal attributes, as explained by the social identity theory.
[25] Research shows that the medial prefrontal cortex (mPFC) region displays increased activity when individuals engage in group categorization.
[26] More specifically, the ventral medial prefrontal cortex becomes active when individuals categorize themselves into groups with whom they already share prior experience which can be based on characteristics such as race, ethnicity, or gender.
This region of the brain is activated due to emotional social reasoning where self-referential processing leads individuals to view the in-group as closer to the self than the out-group.
[27][25] Alternatively, the dorsal medial prefrontal cortex is activated when individuals categorize themselves into groups with whom they have no prior experience with such as randomly being divided into teams to compete in a task.
In this case, individuals must use abstract social reasoning, a part of the dorsal medial prefrontal cortex, to form self-guided ideas for categorical identification.
[27][25] It is important to note that with newly formed groups, individuals do not have an emotional component which is why the ventral medial prefrontal cortex is not activated.
Efferson, Lalive and Fehr published such a study in 2008, utilizing a series of coordination games to mimic cooperation between individuals.
The study found that cultural groups were able to form endogenously through creation of a linkage between a payoff-relevant behavior and a payoff-irrelevant marker.
Their study supported the hypothesis that the formation of cultural groups alters selective pressure facing individuals, and thus leads to certain behavioral traits being advantageous.
Subjects at Purdue and Rutgers University participated in computerized tasks that measured automatic attitudes based on how quickly a person categorizes pleasant and unpleasant attributes with each gender.
[30] In 2001 Fershtman and Gneezy found that men showed in-group biases in a "trust" game based on ethnicity, whereas this tendency was not present in women.
The results showed that men displayed significant in-group favoritism from June all the way to the DNC in August.
[35] Researchers theorized that in-group bias was strong in June, as the competition to be the Democratic nominee in the elections was still recent and thus salient.
Research analyzing articles about 35 inter-group conflicts (e.g., Falklands War) by comparing the corresponding language versions of Wikipedia (e.g., English, Spanish) found evidence for in-group favoritism: While the "in-group" was systematically preferred and presented in a more favorable light, the "out-group" was presented as more immoral and more responsible for the conflict.
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.
According to Ma-Kellams, Spencer-Rodgers and Peng, system justification theory seeks to explain why "minorities sometimes endorse system-justifying views of their group".
[47] Social identity theory[citation needed] and Freudian theorists explain in-group derogation as the result of a negative self-image, which they believe is then extended to the group.
[47] 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.