When we meet someone for the first time, we notice a number of things about them--clothes, gestures, manner of speaking, tone of voice, appearance, and so on. We then draw on these cues to fit the person into a ready-made category. No matter how little information we have or how contradictory it is, no matter how many times in the past our initial impressions of people have been wrong, we still classify and categorize people after meeting them only briefly.
Associated with each category is a schema, a set of beliefs or expectations about something (in this case people) based on past experience and that is presumed to apply to all members of that category. For example, if we see a woman wearing a white coat who also has a stethoscope around her neck, we might reasonably categorize her as a doctor. Further, we might conclude that she is a highly trained professional, knowledgeable about diseases and their cures, qualified to prescribe medication and so forth. These various conclusions follow from most people's schema of a doctor.
Schemata serve a number of important functions. For one thing, they allow us to make inferences about other people. We assume, for example, that a friendly person is likely to be good-natured, to accept a social invitation from us, or to do us a small favor. We may not know these things for sure, but our schema for friendly person leads us to make this inference.
Schemata play a crucial role in how we interpret and remember information. For example, in one sturdy, some subjects were told that they would be receiving information about friendly, sociable men, whereas other subjects were informed that they would be learning about intellectual men. Both groups were then given the same information about a set of 50 men and asked to say how many of the men were friendly and how many were intellectual. The subjects who had expected to hear about friendly men dramatically overestimated the number of friendly men in the set, and those who had expected to hear about intellectual men vastly overestimated the number of intellectual men in the set. Moreover, each group of subjects forgot many of the details they received about the men that were inconsistent with their expectations. In short, the subjects tended to hear and remember what they expected to.
From Psychology - an Introduction by Charles Morris with Albert Maisto, Prentice Hall, 1999
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