On the directionality of key pecking during signals for appetitive and aversive events

Abstract

Pigeons were exposed to a signal paired with either blackout or blackout plus shock and to another signal paired with food superimposed on a baseline of concurrent variable-interval reinforcement of pecks on two keys. The signals were changes of color of one of the two keys. The rate of pecking both keys during the signal paired with blackout or blackout plus shock was lower than the baseline rate of pecking (a conditioned emotional response), but the decrease in pecking was greater on the signal key. When the intensity of shock was increased, the rate of pecking did not decrease further on the signal key but did decrease on the other key. Rate of pecking during the signal paired with food increased sharply on the signal key (an autoshaping effect) and decreased sharply on the other key. These results support a view that there are two effects of the interaction between classical and instrumental conditioning, a stimulus-directed effect and a generalemotional effect.