The Cognitive Consequences of Using Categorical versus Dimensional Classification Systems: The Case of Personality Disorder Experts


Features are inherently ambiguous in that their meanings depend on the categories they describe (e.g., small for planets vs. molecules; Murphy, 1988). However, a new proposal for the next version of the DSM (DSM-IV-TR, Diagnostic and Statistical Manual of Mental Disorders, 4th Ed., text revision; American Psychiatric Association, 2000) advocates eliminating personality disorder categories, instead describing patients using only dimensions with the well-known Five-Factor Model. We investigated whether experts in personality pathology are able to translate dimensional patient descriptions into their corresponding diagnostic categories in the current version of the DSM. The results showed that even experts had considerable difficulty disambiguating the meaning of the dimensions to determine correct diagnoses and found the utility of the dimensional system to be lacking. Implications for categorization research are discussed.

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