Pavlovian conditioning: the CS-UR relation.

A new Pavlovian procedure used fluid-elicited throat-movement responses of the pigeon (N=66) to study the effects on conditioning of the temporal relation of the conditioned stimulus (CS) to the unconditioned stimulus-unconditioned response (US-UR). Because the throat-movement response has a substantial latency and duration, the relation of the CS to the US and UR could be independently evaluated. Four experiments indicated that, operationally, the relation of the CS to the UR--not to the US--is critical for conditioning in this preparation. The conventional emphasis on CS-US relations is based on procedures that confound the occurrence of the US with the UR and that foster generalization decrement between training and testing. The authors indicate how several conditioning phenomena may be reinterpreted in terms of CS-UR relations.