Methods for measuring the strength of discriminable drug effects

Drug discriminations can be used to investigate a variety of preclinical psychopharmacological issues. These discriminations are based on the so-called "discriminable" or "discriminative stimulus" effects of drugs. In order to conduct some types of drug discrimination studies, it is helpful or necessary to know the amount or degree of discriminability of the various drugs employed. This paper describes several methods for determining the degree of discriminability of drugs, and evaluates these methods primarily using data obtained by training rats to discriminate drug vs. no drug in a shock-escape T-maze task. The results suggest that useful indices of degree of discriminability can be computed from the rapidity with which drug discriminations are learned. Indices based on average accuracy during acquisition were found to be somewhat superior to indices based on sessions to criterion.