STIMULUS CONTROL IN FIXED AND VARIABLE TEMPORALLY-DEFINED SCHEDULES

Résumé 0

In order to evaluate the development of stimulus control, six rats were exposed to a temporally defined reinforcement schedule (T = 60-s, = 0.5) in which tD and tΔ were correlated with different auditory stimuli and with reinforcement probabilities of 1 and 0, respectively. For three rats, tD subcycle always was followed by tΔ subcycle, while for the remaining rats both subcycles were presented randomly (p = .5) within the session. At the end of the experiment, lever-pressing response frequencies were higher during tD and in the presence of the stimulus that signaled such subcycle than during tΔ subcycle for all rats. Results indicate that the limited-hold reinforcement in temporally defined schedules does not necessarily prevent stimulus control, and that such control develops without any behavioral pattern derived from sequential regularity between subcycles. Additionally, results call in to question the possible development of a conditioned reinforcement function by the stimulus in tΔ subcycle.