Behavioral determinants in the expression of the Kamin blocking effect: Implications for associative learning theory

Associative learning makes important contributions to our behavior and decisions. The Kamin blocking effect is an associative learning phenomenon that plays a central role in understanding of the psychological principles underlying associative learning. However, several recent failures to replicate the blocking effect suggest that the conditions necessary for blocking are poorly understood. To understand the conditions necessary for blocking, here we review studies into the expression of blocking in subjects that either approach and interact with the conditioned cue (sign trackers) or approach and interact with the reward location (goal trackers) during appetitive classical conditioning. Psychological theory and the neurophysiological correlates of appetitive classical conditioning make opposing predictions regarding the expression of blocking in sign and goal trackers. We reconcile these opposing predictions in a qualitative model using two parallel learning processes. Such models offer a better framework for understanding the psychological associative structures acquired during learning, their interactions contributing to the conditioned response, and how they affect subsequent learning and the expression of the Kamin blocking effect.