The Role of Background Stimuli during Pavlovian Conditioning

Abstract

An investigation was carried out into the part played by background stimuli during Pavlovian conditioning. Groups of rats were presented with tone CSs and unavoidable foot-shock USs. Both CS-US conditional probabilities and US intensity were manipulated across groups. Subsequently all animals were tested for their reactions to the environment in which they had previously been trained. During tests neither the CS nor the US was presented. It was found that the degree to which rats avoided the environment was inversely related to the probability of the CS being followed by a US and directly related to the level of US intensity to which they had been exposed during training. The results largely supported Rescorla and Wagner's (1972) theory of Pavlovian conditioning.