Maintenance of behavior controlling the duration of discriminative stimuli.

THE MAINTENANCE OF A RESPONSE CONTROLLING THE DURATION OF POSITIVE AND NEGATIVE DISCRIMINATIVE STIMULI IN A MULTIPLE SCHEDULE WAS EXAMINED WITH RESPECT TO THE POSSIBLE CONSEQUENCES OF THE RESPONSE: none, escape from the negative stimulus, production of the positive stimulus, and initiation of the reinforcement schedule associated with the latter. The last two seemed to be the major factors in producing and maintaining the response. Escape from the negative stimulus maintained it in most subjects, but only at a much lower level.