In three experiments, the hypothesis that diazepam (Valium) selectively impairs the transfer of information from short-term to long-term memory was supported by differences between placebo and drugged subjects in effects of item difficulty, serial position (primacy-recency), and list length. In Experiment I, diazepam reduced recall in the primacy portion of the serial position function, but produced no performance difference in the recency component. Recall decreased in placebo subjects as item difficulty increased, but drugged subjects were relatively uaffected by manipulation of difficulty. In Experiments 2 and 3, subjects treated with diazepam exhibited smaller gains in immediate recall with increasing list length than placebo controls. Retrieval of words learned before drug administration was not impaired by diazepam; in fact, it was significantly enhanced relative to control performance. The results add further support to the distinction between short-and long-term memory.Since the 1960s, a dominant approach to learning and memory processes has been to divide memory into two components: a limited-capacity, short-term-memory (STM) store and a large-capacity, long-term-memory (LTM) store (see Atkinson & Shiffrin, 1968, 1971, and Waugh & Norman, 1965. Although there are a number of criticisms of the duplex model that have forced modifications of the theory (for a review, see Klatzky, 1980), it continues to be a comprehensive and useful approach to the analysis of human memory. The present paper is intended to illustrate the usefulness of the model in the growing area of cognitive psychopharmacology and also to illustrate how pharmacological manipulations can be utilized to investigate specific human memory processes.The literature on cognitive psychopharmacology contains many studies of drugs with similar and specific detrimental effects on memory (e .g., Birnbaum & Parker, 1977;Crow & Grove-White, 1973 ;Darley, Tinklenberg, Roth, Hollister, & Atkinson, 1973; Ghoneim & Mewaldt, 1975. Illustrative of these drugs is diazepam (Valium), until recently the most often prescribed drug in the world. The specific memory impairment produced by diazepam has been well demonstrated.This research was supported by NIMH Grant MH 35324. A portion of this paper was presented at the Psychonornic Society meeting in Minneapolis, November 12, 1982. We thank Nancy Fallis and Janis L. Berie for their assistance. Requests for reprints should be sent to Steven P. Mewaldt, Department of Psychology, Marshall University, Huntington, West Virginia 25701.For example, diazepam impairs acquisition of serial, paired-associate, and free-recall lists, but does not affect performance on a Brown-Peterson distractor task or a short memory span task, or, apparently, hinder retrieval of previously acquired information (see Clarke, Eccersley, Frisby, & Thornton, 1970; Dundee & Pandit, 1972; Ghoneim & Mewaldt, 1975 Hinrichs, Mewaldt, Ghoneim, & Berie, 1982). We have interpreted these data as suggesting that diazepam leaves STM and retrieval from LT...