Animal learning and motivation and addictive drugs.

Highlights of a systematic analysis of the abstracts of over 1700 publications dealing with addictive drugs (primarily alcohol) in the context of animal learning and motivation are summarized under two main headings. The behavioral effects of drugs vary with the nature of the drug, the dosage, and the behavioral baseline; behavioral tolerance frequently results from continued practice in the drug state. The paradigmatic effects show that drugs can function effectively as conditional stimuli, unconditional stimuli, responses, and reinforcers. As a result, drug habits develop their own motivational support, leading to conditioned tolerance and conditioned addiction. It is contended that principles of animal behavior can provide a basis for a theory of human drug use and abuse, but that voluntary control of addictive behavior requires uniquely human cognitive processes.