Behavioral Defeat in Squirrel Monkeys: An Experimental Model of Reactive Depression

Abstract

The combination of a progressive FR schedule of reinforcement and the opportunity to “escape” from this schedule produced a syndrome in the squirrel monkey with prima facie similarity to human reactive depression. This condition was created by a progressive increase in work demanded per reward and a corresponding reduction in density of reinforcement. The syndrome was characterized by progressive reduction of positively reinforced behavior, withdrawal from the environment, task ambivalence, and signs of emotional stress. These behaviors were ameliorated by environmental change which reduced the experientially produced stress and were dramatically reversed by the anti-anxiety agent, chlordiazepoxide.