Prejudice: Definition and How It Forms in the Mind and in Groups

Prejudice and Stereotypes: Definition and a Few Examples

A policy resolution from the American Psychological Association draws a clear line between the two terms. A stereotype is a generalized belief about the traits of a group; prejudice is an unfavorable emotional reaction toward that group. Discrimination is about behavior: differential treatment carried out by individuals, or policies and institutional settings that keep an inequality going over time.

The APA notes that the shape these take shifts with the historical and social moment. Open, hostile forms of prejudice exist alongside more modern, automatic ones that are hard to spot in any single instance; some blend positive and negative feelings, such as a patronizing attitude or envy toward a group. They fall most often on groups with less social power, for instance by ethnicity or economic standing, and research cited by the APA measures a real cost in lower psychological wellbeing and changed behavior among the children who are their target.

How They Form: Social Categorization

A 2019 developmental psychology review by Marjorie Rhodes and Andrew Baron, published in Annual Review of Developmental Psychology, points to social categorization as the shared mechanism behind both stereotypes and prejudice, a topic close to psychological science more broadly. It is a universal process: it helps children, and later adults, make sense of an otherwise overwhelming social world by grouping people according to shared traits. In adults this sorting happens on its own and shapes how we think and act. Rhodes and Baron argue that the very ability that lets people navigate the social world is also the ground on which stereotypes, prejudice and discrimination can grow.

Infants start sorting faces into distinct categories around six months of age, according to the same review. Categorizing by gender comes a little later, between seven and ten months.

The ability to tell apart faces of different races also depends on the environment a child grows up in. A 2006 study of three-month-old infants in Israel and Ethiopia, cited by Rhodes and Baron, found that babies raised in a visually homogeneous racial environment looked longer at faces from their own ethnic background, while infants exposed to both white and Black faces showed no such preference. The belief that race is an objective way to divide people develops later, between seven and ten years of age, and its strength varies with the diversity of the community a child grows up in and with their parents’ political views.

The Minimal Group and the Weight of Belonging

In the 1970s, psychologist Henri Tajfel and his colleagues proposed social identity theory: people identify with members of their own group, and that self-identification feeds back into social categorization. One of the most cited findings from the research tradition that followed, the minimal group paradigm, is that favoritism toward one’s own group appears even when the similarity between people is minimal and entirely arbitrary, with no competition or cooperation involved. Simply perceiving oneself as a member is enough; there is no need to know anything about the other members or ever expect to meet them.

This favoritism shows up readily in preschool and early school-age children: being randomly assigned to a group is enough to make a child want to play with its members and trust them more. The same preference also leads to sharing more with them and, overall, rating them more favorably. Identifying with one’s own group also leads children to remember its positive behaviors and the other group’s negative ones more selectively, reinforcing over time a more favorable view of whoever counts as part of the same group. Kurt Lewin’s work on group dynamics starts from a related question, what holds the members of a group together. With stereotypes, the bond comes from perceived belonging itself, even when there is no real similarity behind it.

How They Spread: The Language Adults Use

Stereotypes pass from one generation to the next even without a single explicit lesson.

Practical example: an adult might simply say, in a neutral tone, “girls do this”: a generic sentence, said with no teaching intent at all, that is still enough to plant in a child’s mind the idea that the category holds deep similarities among its members.

It is the same principle behind Albert Bandura’s social learning theory: people pick up behaviors and ideas by watching others, not only by being taught directly. Sorting people into categories, for that matter, is one of the processes that cognitivism treats as active information processing.

Intergroup Contact Reduces Prejudice, Under Certain Conditions

Psychologist Gordon Allport proposed in 1954 that contact between different groups can reduce prejudice when it meets specific conditions: cooperation toward a shared goal, a perceived equality of status between the groups, an ordinary and non-artificial setting, and ideally the backing of the community’s institutions. The APA reports that taking part in demographically mixed settings has the potential to lower prejudice toward members of an outgroup.

A 2026 study in Developmental Science shows that bringing two groups together, on its own, can leave mutual prejudice unchanged. The researchers worked with 481 children aged 5 to 10, from Rohingya refugee communities and from the Bangladeshi community hosting them: both groups showed strong favoritism toward their own group, more pronounced among the host-community children and increasing with age within this range. A single virtual collaboration session with a peer from the other group left this prejudice unchanged across every measure used. The authors themselves link the result to two of Allport’s conditions their experiment did not meet, including an ordinary, non-artificial setting, one possible reason why contact on its own fell short here.