The psychological categorization of people into in-group and out-group members is associated with a variety of phenomena. The following examples have all received a great deal of academic attention.
In-group favoritism This refers to the fact that under certain conditions, people will prefer and have affinity for one's in-group over the out-group, or anyone viewed as outside the in-group. This can be expressed in one's evaluation of others, linking, allocation of resources, and many other ways. How we perceive the actions of others is also affected by in-group favoritism. People may perceive the same action very differently depending on whether the action was executed by a member of the same group or a member of a different group. In fact, people tend to evaluate actions of their own group or team members much more favorably than those of outgroup members. This phenomenon was demonstrated in an empirical study conducted by Molenberghs and colleagues in 2013. Although they had watched the same motion picture of the game, their versions of what transpired were so starkly different it appeared as though they had watched two totally different games. Research indicates that individuals are faster and more accurate at recognizing faces of ingroup vs. outgroup members. For example, researchers in a cross-race recognition study recorded blood oxygenation level-dependent signal (BOLD) activity from black and white participants while they viewed and attempted to remember pictures of unfamiliar black faces, white faces and objects. They found that participants in this study exhibited greater activity in the
fusiform face area (FFA), an area of the
fusiform gyrus located in the inferior temporal cortex of the brain linked to object and face recognition, when viewing same race faces compared to other race faces. This suggests out-group or unfamiliar faces may not be "faces" with the same intensity as in-group faces. Prior research has also shown that the devaluation and dehumanization of outgroup members is exacerbated when the initial encoding and configural processing of an outgroup face is impeded. So not only does this initial encoding process dehumanize outgroup members, it also contributes to a homogeneity effect, whereby outgroup members are perceived as more similar to each other than ingroup members.
Group homogeneity Categorization of people into social groups increases the perception that group members are similar to one another. An outcome of this is the out-group homogeneity effect. This refers to the perception of members of an out-group as being homogenous, while members of one's in-group are perceived as being diverse, e.g. "they are alike; we are diverse". This is especially likely to occur in regard to negative characteristics. Under certain conditions, in-group members can be perceived as being similar to one another in regard to positive characteristics. This effect is called in-group homogeneity. In-group and out-group may heavily dictate how one may think. It may rewrite threat detection to out-group members. And people filter reality through lenses that may interpret the same threats as opposite based on the group. This concept may be extrapolated to many different real-life scenarios and even wars. These radically changing thoughts between groups can be seen similarly in groupism. In-group and out-group may be differentiated very minimally, such as choosing groups by coin flip. However, although these traits may seem unintuitive, they were superior for evolution.
Out-group derogation Discrimination between in-groups and out-groups is a matter of favoritism towards an in-group and the absence of equivalent favoritism towards an out-group. Out-group derogation is the phenomenon in which an out-group is perceived as being threatening to the members of an in-group. This phenomenon often accompanies in-group favoritism, as it requires one to have an affinity towards their in-group. Some research suggests that out-group derogation occurs when an out-group is perceived as blocking or hindering the goals of an in-group. It has also been argued that out-group derogation is a natural consequence of the categorization process.
Social influence People have been shown to be differentially influenced by in-group members. That is, under conditions where group categorization is psychologically salient, people will shift their beliefs in line with in-group
social norms.
Group polarization This generally refers to the tendency of groups to make decisions that are more extreme than the initial inclination of its members, although polarization toward the most central beliefs has also been observed. It has been shown that this effect is related to a psychologically salient in-group and outgroup categorization. ==Postulated role in human evolution==