Date of Award


Degree Type


Degree Name

Doctor of Philosophy in Psychology



First Advisor

David Faust


A correct diagnosis may be critical to the implementation of an appropriate treatment plan for a patient. Many factors contribute to the difficulty of assigning a correct psychiatric diagnosis, including misuse, or less than optimal use, of information. Many studies have documented underutilization of base rate data in prediction. Research into the use of stereotypes has demonstrated that too much reliance on an individual's membership in a group may also affect decision making. What is the appropriate use of base rate data and group membership in psychiatric diagnosis? It was hypothesized that participants would underutilize base rates in a low base rate condition and overutilize base rates in a high base rate condition when gender stereotypes were not a factor. This hypothesis was supported by the results of the study, that is, there was a marked tendency for participants' answers to deviate from the base rate, in the high (80%) and low (20%) base rate cases, toward the midpoint (50%). It was further hypothesized that gender stereotypes would unduly influence psychologists' estimates that a patient has a particular personality disorder, that is, that clinicians would underutilize base rate information and rely on their prototypes of two personality disorders to make diagnostic decisions. This hypothesis was partially supported by the results of this study. Although clinicians underutilized base rate information, it was not apparent that their decision making was adversely affected by gender stereotypes. Rather, participants tended to rely on a piece of extraneous information that was provided, that is, the diagnosticity of a test that was given as 50%. It was also hypothesized that clinicians would assign higher probabilities for psychopathology to females than to males overall. This hypothesis was not supported by the results of this study. This may be because psychologists are not inappropriately influenced by gender stereotypes, at least within certain contexts. Certain limitations in the study may also contribute to the findings.



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