Out-group homogeneity effect
Also known as: Out-group homogeneity
'They' all seem alike; 'we' are richly individual.
What it means
The out-group homogeneity effect is the tendency to perceive members of an out-group as more similar to one another than members of one's own in-group, whom one sees as varied and distinct individuals. The mechanism is partly informational — people typically have more and deeper exposure to in-group members, encountering them across many contexts, while out-group members are met more rarely and in narrower roles — and partly motivational, as categorizing 'them' simplifies a less familiar group. Because the out-group is encoded at the level of the category rather than the individual, its members are stored as interchangeable exemplars of a type, which is the cognitive substrate of stereotyping. The effect is not merely a function of group size, since even majorities can show it toward minorities, and it can attenuate with genuine, individuating contact. It contributes to prejudice, dehumanization, and the discounting of out-group members' individuality and suffering. It matters because seeing an out-group as a uniform mass makes stereotypes feel accurate and makes empathy and fair treatment harder.
Examples
Fans of a rival team are dismissed as 'all the same,' while your own fans are obviously a diverse bunch of distinct people.
Engineering discusses 'what sales is like' as if the department had a single personality, while cheerfully listing seven distinct characters within its own team — the seven it eats lunch with.
Older colleagues describe Gen Z as one mind with one attitude to work. The same people can tell you in detail how each of their three grandchildren differs from the other two.
First described in Quattrone & Jones (1980).