The Barnum effect in a computerized Rorschach interpretation system.

Twelve psychiatric outpatients were administered the Rorschach test, and results were interpreted using the Exner (1983, 1986) Report for the Comprehensive System computer-based test interpretation (CBTI) program. Four psychiatrists made accuracy ratings for both real and bogus reports for each of their patients. Data were analyzed using two-way analyses of covariance (ANCOVAs), where report type was a repeated main effect, psychiatrist was a random main effect, and the number of statements in the report was the covariate. Results indicated that this CBTI provided only 5% discriminating power for any one patient, with 60% of the interpretive statements merely describing typical characteristics of the outpatient population. No significant psychiatrist, interaction, or covariate effects were encountered.