The prototype as a construct in abnormal psychology: 2. Clarifying disagreement in psychiatric judgments.

This article examines three hypotheses suggested by the concept of a prototype. The first hypothesis is that an observer's impression of a target person depends on the number of prototypic features present in the stimulus description. Study 1 showed that a target person was judged to be more depressed if the case description contained many features of the prototype of a depressed person. The second hypothesis is that disagreement among judges occurs when fewer prototypic features are present in the stimulus. When, in Study 2, a psychiatric interview contained only a few features from the prototype of a depressed person, those features seemed to activate the full prototype in some observers and failed to do so in other observers, producing disagreement among judges about the degree of the person's depression. The third hypothesis is that a shortage of relevant prototypic features is more critical to diagnostic disagreement than the presence of irrelevant features. Study 3 supported this hypothesis. We also discuss the kind of ambiguity that occurs when "contradictory" prototypes are simultaneously activated.