An analysis of drug-seeking behavior in animals.

This article reviews the literature on the behavioral aspects of opiate dependence. Available data on the variables affecting drug-maintained behavior are presented. These variables are: (a) reinforcement variables, including parameters such as delay, magnitude, rate and duration of the reinforcing stimulus; (b) antecedent conditions, such as deprivation and satiation; (c) organismic variables, such as genotype, species, sex and age; (d) current environmental contingencies, such as the schedule of reinforcement in effect, or extinction; and (e) such experiential variables as pharmacological and behavioral history of the organism. The review ends with a discussion of the implications of these variables for the treatment of drug abuse.