The functional properties of a time out from an avoidance schedule.

Investigations are reported of some of the discriminative (cue) and reinforcing properties of stimuli (TO(av)) correlated with the discontinuation of a free-operant avoidance schedule. After several unsuccessful initial attempts to demonstrate the positively reinforcing effect of TO(av), a special technique was developed. The subjects were trained by means of a free-operant avoidance procedure to press a lever and postpone electric shock; by pressing a second lever, they could produce a cue correlated with the TO(av) period. The importance of a distinct cue correlated with TO(av) was demonstrated in experiments in which this signal was eliminated from the procedure. The reinforcing function of the TO(av) period was explored by showing its effectiveness under various schedules of reinforcement. Other observations were made concerning the course of extinction of both TO(av)-producing responses and avoidance behavior. In further experiments in which TO(av) was used as a reinforcer, the TO(av) behavior was also brought under separate stimulus control. The development of the various discriminations involved in the resulting performance were described.