Differential Control of Responding Following Beak Injury

Abstract

A pigeon that injured its beak pecking a response key subsequently exhibited an aversion to continuous key pecking even though near 70% of free feeding weight and its beak was healed. When placed in the chamber, it would peck the key once but would not respond again for sessions of 1½ hours. Key pecking was then shaped using a procedure consisting of removing the bird after one reinforced key peck. This operation was continued for 7 “in/out” trials. On the 8th trial the bird continued responding with an interresponse time of less than 30 sec. The schedule was then faded to a terminal value. The results suggest that stimuli associated with the beginning of the session controlled the initial key peck, whereas those occurring during the session were paired with injury and inhibited continuous responding.