How many times have we heard about ‘all X’s are the same’? People tend to group people who share some kind of trait under a single definition, falsely attributing to them common characteristics.

This phenomenon is what in social psychology has been called effect of homogeneity relative to the exogroup , and in the present article we are going to see it with greater depth.

Homogeneity effect relative to the exoskeleton: definition

The effect of homogeneity relative to the exo-group is a social phenomenon that occurs when a person, who belongs to a certain group, sees the members of other groups as more similar to each other, while he or she perceives the members within the same group as very varied. That is to say, this phenomenon refers to how we people tend to see the exogroup, that is to say, an alien group, as something uniform , while we are aware of the nuances present in the endogroup, our own.

When we meet someone, we tend to get a first impression, which can be very influenced by the way we see, in very general terms, the rest of their fellow human beings who share some characteristic. These characteristics may be race, gender, age, nationality, profession, among many others .

As you can understand, this trend, so common in most human beings, is the raw material that stereotypes are used for.

Between the error bias and the adaptive mechanism

There is some controversy about whether this phenomenon should be considered as a bias due to mistaken beliefs or, instead, whether it serves as an adaptive mechanism of social perception.

With bias, in this case, we would refer to that people, based on a wrong information, establish judgments of others without really knowing how they are , while, as an adaptive mechanism of social perception, this effect would have the function of simplifying the information of the world, making that the generalization and categorization would help us to synthesize the world.

Study of this phenomenon

One of the first scientific approaches to this effect is found in the work of Jones, Wood and Quattrone in 1981. In their study they asked college students, who frequented four different clubs, what they thought of the members of their own club and those who frequented the other three.

The results showed that there was an important tendency to generalize in terms of the description of the members of the other clubs, attributing to them the same characteristics and behaviors. On the other hand, when they talked about their own club, they emphasized more that there were individual differences , that each one was like he was and not because they went to the same place they had to be the same.

Many other studies have addressed this phenomenon but taking into account characteristics that are difficult to modify, such as gender, race and nationality. It is well known that in the United States, especially in cities where the distribution of black and white people is very localized in different neighborhoods, as one moves away from black majority neighborhoods and into white majority neighborhoods, the idea that the other race is all the same becomes much stronger.

Possible explanations for this effect

Although research might suggest that the reason people tend to generalize about the characteristics of people who belong to a group other than their own is because of a lack of contact between members of one group and another, this has been found not to be the case.

One might think that, not knowing the members of another group, encourages stronger stereotypes and prejudices, arising from lack of contact and avoidance of taking it. However, there are many cases in everyday life that prove this belief to be false.

A clear example of this is the differentiation that men and women make with respect to the other gender. These prejudices do not arise because men have little contact with women and vice versa , given that, although it is true that men and women tend to have more friends of their gender, there are not few people of the other gender who are usually part of the contact list. Sayings such as ‘all men/women are equal’ do not arise precisely from ignorance, but from an interest in generalizing about the other group.

It is for this reason that it has been necessary to put forward some more sophisticated explanations to better understand why this is so. One of them is the way in which humans store and process information concerning the endo and exogroup . One of the theories that has best exposed this idea is the theory of self-categorization.

Theory of self-categorization

According to this theory, the effect of homogeneity to the exogroup is given due to the different contexts present at the time of perceiving the endo and exogroup.

Thus, hypothetically, the effect of homogeneity to the exogroup occurs because of different contexts, in which both intra and inter-group comparisons are made .

When a person who belongs to a certain group is aware of another group, it is normal to make a comparison between his group and the other, and here an inter-group process takes place.

To facilitate this comparison, it is necessary to synthesize the information corresponding to both one’s own group and the other, that is, to make generalizations about both the endo and the exo group; this way the process is easier.

It is here that special emphasis is placed on characteristics that are shared by the majority of the members of the ex-group, with the idea that they are all equal remaining in the memory . However, when we move on to exclusively compare the members of the endogroup, that is, an intragroup process, it happens that we pay more attention to differential features among its members.

By being part of the same group and getting to know several of its members better, he will be aware of the individual differences of his peers, differentiating between himself and his peers.

The theory of self-categorization has shown some evidence that in inter-group situations, both the endo and the exo-group are perceived more homogeneously. However, in a context where one group is isolated from others, differences and heterogeneity arise more easily.

Bibliographic references:

  • Quattrone, G. A.; Jones, E. E. (1980). The perception of variability within in-groups and out-groups: Implications for the law of small numbers. Journal of Personality and Social Psychology. 38 (1): 141-152. doi:10.1037/0022-3514.38.1.141
  • Judd, C. M.; Ryan, Carey S.; Park, B. (1991). Accuracy in the judgment of in-group and out-group variability. Journal of Personality and Social Psychology. 61 (3): 366-379. doi:10.1037/0022-3514.61.3.366
  • Rubin, M., Hewstone, M., Crisp, R. J., Voci, A., & Richards, Z. (2004). Gender out-group homogeneity: The roles of differential familiarity, gender differences, and group size. In V. Yzerbyt, C. M. Judd, & O. Corneille (Eds.), The psychology of group perception: Perceived variability, entitativity, and essentialism (pp. 203-220). New York: Psychology Press.