Behavioral pharmacology and verbal behavior: Diazepam effects on verbal self-reports

Abstract

Diazepam (10 mg) was administered to two men performing a delayed matching-to-sample task in which the number of elements in a compound sample stimulus (one of which appeared among 4 comparison stimuli) was manipulated from 1 to 3. After each trial, subjects pressed either a “Yes” or “No” button in response to a computer-presented query about whether the last choice met a point contingency requiring selection of the matching comparison stimulus within a time limit. Diazepam simultaneously produced marginal decreases in matching-to-sample performance and more pronounced decreases in the accuracy of self-reports about the same performance. Diazepam selectively increased false reports of success; false reports of failure were not systematically affected. A signal-detection analysis summarized these patterns as a decrease in self-report discriminability (A′) with no systematic change in bias (B′_H). These preliminary results converge with those of clinical lore and the results of studies with other benzodiazepine drugs in suggesting that diazepam can produce an “overconfidence” in performance self-evaluation, the mechanisms and parameters of which remain to be identified. The results were inconsistent with those of one previous study of diazepam’s effects on performance self-evaluation, but given procedural differences between the two studies, the discrepancy may reflect the functional independence of verbal operant classes in Skinner’s (1957) taxonomy.