Effects of a response-reinforcer relation on elicited pecking.

Three pigeons were exposed for 22 sessions to a variant of a multiple variable-time 1-min extinction reinforcement schedule in the presence of a white key. A 1.5-s stimulus change (red) preceded each 1-min component during which food was delivered and a 1.5-s stimulus change (green) preceded each extinction component. The variable-time 1-min schedule was then changed to a variable-interval 1-min schedule for several sessions and then returned to variable time 1-min. During the first exposure to noncontingent reinforcer delivery, two of the three birds pecked frequently during the 1.5-s red stimulus but not during the other components. The third bird did not keypeck. The addition of a response-reinforcer relation resulted in all three birds pecking during the red stimulus as well as during the white stimuli. Pecking rates were usually highest during red. Response rates during green remained low. The subsequent removal of the response contingency resulted in a decrease in responding during white, and for two of the three birds, a decrease in responding during the red stimulus. The results support an interpretation of signal key pecking in stimulus separation procedures as elicited key pecking controlled by the stimulus-reinforcer relation.