From general processes to individual differences: Pavlov’s legacy

Pavlov observed his dogs salivated not only when food was directly introduced into their mouths, but also during other stimuli that had co-occurred with the delivery of food in the past. This serendipitous finding has had a profound impact in many fields of science and is one that is widely known to non-specialists and lay publics alike. Pavlov imagined the general principles discovered in studying what came to be known as Pavlovian conditioning might have broad applicability, and the study of Pavlovian conditioning has resulted in general-process models of learning and memory that have themselves had significant impact. However, Pavlov also observed marked individual differences in the behavior of his dogs, which he was keen to bring within his general-process perspective. In this spirit, our own recent research concerns reconciling general-process theories of associative learning with qualitative and quantitative individual differences in such conditioned behaviors; in particular, responses directed toward the conditioned stimulus (called sign-tracking) and those reflecting the unconditioned stimulus (called goal-tracking). The research has prompted some revisions to received wisdom, including the nature of associative structures involved, and the rules governing their acquisition and translation into behavior.