When we start to align our identity to group membership there are many troubling ways of thinking that we might find ourselves falling into. The out-group homogeneity effect is once such way of thinking. Put in simple terms it is the effect of thinking that those within your group are complicated, diverse we nuanced and differing opinionl, perspectives and motivations. However those to whom your group holds itself in opposition are simplistic and all the same.
This way of thinking is clearly flawed,
There is always the danger that those who think alike should gravitate together into ‘coteries’ where they will henceforth encounter opposition only in the emasculated form of rumor that the outsiders say thus and thus. The absent are easily refuted, complacent dogmatism thrives, and differences of opinion are embittered by group hostility. Each group hears not the best, but the worst, that the other groups can say.
The out-group homogeneity effect is part of a broader field of research that examines perceived group variability. This area includes in-group homogeneity effects as well as out-group homogeneity effects, and it also deals with perceived group variability effects that are not linked to in-group/out-group membership, such as effects that are related to the power, status, and size of groups.
The out-group homogeneity effect has been found using a wide variety of different social groups, from political and racial groups to age and gender groups.
The implications of this effect on stereotyping have been noted. Perceivers tend to have impressions about the diversity or variability of group members around those central tendencies or typical attributes of those group members. Thus, outgroup stereotypicality judgments are overestimated, supporting the view that out-group stereotypes are overgeneralizations.
The outgroup homogeneity effect is sometimes referred to as "outgroup homogeneity bias". Such nomenclature hints at a broader meta-theoretical debate that is present in the field of social psychology. This debate centres on the validity of heightened perceptions of ingroup and outgroup homogeneity, where some researchers view the homogeneity effect as an example of cognitive bias and error, while other researchers view the effect as an example of normal and often adaptive social perception.