An experimental analysis of "empathic" response: Effects of pain reactions of pigeon upon other pigeon's operant behavior.
Suppression of operant behavior by exposure to pain reactions of conspecifics was examined with pigeons. Three groups of pigeons were trained on a VI schedule, and were then exposed to the pain reactions of an adjoining bird to electric shocks. Although every subject showed suppression of responding, the suppression decreased with repeated exposures. Following this assessment, a conditioning group received conditioned suppression training in which the pain reaction of the adjoining bird was the CS and an electric shock was the US; a shock exposure group received the electric shock without any explicit CS; and, a no-shock group did not receive any shock. After these treatments, every group was exposed to the pain reactions of the adjoining bird (test 1). The conditioning group and the shock exposure group showed clear suppression in responding, but the no-shock group did not. The no-shock group then received the shock exposure treatment and the conditioned suppression training succesively, and the shock exposure group received the conditioned suppression training. Results of tests with the pain reaction of the adjoining bird supported the results of the test 1, however, suppression caused by the shock exposure was not so clear in the no-shock group. The present results demonstrated that conspecific behavior can become a CS by conditioned suppression training, and, the behavior to an aversive stimulus can acquire aversive properties for other conspecifics when they have shared the exposure to the same aversive stimulus.