Punishment of schedule-induced drinking in rats by signaled and unsignaled delays in food presentation.

Food-deprived rats were exposed to a fixed-time 60-s schedule of food-pellet presentation and developed schedule-induced drinking. Using an ABA reversal design, three experiments investigated the effects of events then made dependent on licks. In Experiment 1, lick-dependent signaled delays (10 s) in food presentation in general led to decreased drinking, which recovered when the signaled delays were discontinued. The drinking of yoked-control rats, which received food at the same times as those exposed to the signaled-delay contingency, showed much smaller changes. Experiment 2 showed that 10-s lick-dependent signals alone did not reduce drinking. In Experiment 3, when licks produced unsignaled 10-s delays in food there were less marked and more gradual changes in drinking than in Experiment 1, although these effects again were greater than with yoked-control animals. We concluded that both signaled and unsignaled delays functioned as punishers of drinking. These findings support the view that schedule-induced drinking, like operant behavior, is subject to control by its consequences.