One way to explain how stereotypes are formed is to use the claims of schema theory. To recap, schema theory argues that we organize information in our mind by unconsciously creating categories (these categories are the schemas). We do this because we encounter millions of units of information on a daily basis and if we didn’t simplify this information into easily comprehensible categories (schemas), we’d burn ourselves out and our cognitive energy would be drained. So according to schema theorists, one of the primary functions of schemas is to allow us to make generalizations about people, places and things. Making these generalizations makes it easier to understand and make sense of new information we process. This includes making generalizations about groups of people.
From this summary of schema theory, it should be rather straightforward to see how this could explain stereotypes. After all, stereotypes are widely held generalizations about a group of people. Therefore, schema theory can explain the formation of stereotypes by arguing that we naturally categorize people into groups and we make generalizations about the characteristics of those groups so that it makes it less cognitively demanding (easier) think about the individuals we meet on a daily basis. For example, it’s cognitively easier for me to think about Asians as being good at math, rather than thinking that there’s as much variation in math abilities in Asian people as in any other racial group.
But where do these schemas about groups of people (the stereotypes) come from in the first place? The above explanation can give a reason why they occur, but it doesn’t necessarily explain how. In fact, the origin of schemas isn’t straightforward and is the source of much debate among cognitive and social psychologists. For a good explanation of how stereotypes form, I recommend investigating the out-group homogeneity effect (See pg. 164-65 of IB Psychology: A Student’s Guide). By combining schema theory and the out-group homogeneity effect, you can develop a well-developed explanation of the formation of stereotypes.
Schema theory is one piece of research that can be used to explain the formation of stereotypes. Another is to look at the out-group homogeneity effect, as shown in Park and Rothbart’s (1982) study on sorority girls (Read more).