Current thinking about Pavlovian conditioning differs substantially from that of 20 years ago. Yet the changes that have taken place remain poorly appreciated by psychologists generally. Traditional descriptions of conditioning as the acquired ability of one stimulus to evoke the original response to another because of their pairing are shown to be inadequate. They fail to characterize adequately the circumstances producing learning, the content of that learning, or the manner in which that learning influences performance. Instead, conditioning is now described as the learning of relations among events so as to allow the organism to represent its environment. Within this framework, the study of Pavlovian conditioning continues to be an intellectually active area, full of new discoveries and information relevant to other areas of psychology.

Pavlovian conditioning is one of the oldest and most systematically studied phenomena in psychology. Outside of psychology, it is one of our best known findings. But at the same time, within psychology it is badly misunderstood and misrepresented. In the last 20 years, knowledge of the associative processes underlying Pavlovian conditioning has expanded dramatically. The result is that modern thinking about conditioning is completely different from the views psychologists held 20 years ago. Unfortunately, these changes are very poorly appreciated by psychologists at large. The last time many psychologists read anything about Pavlovian conditioning was before these changes took place. Even those more recently educated often received that education from textbooks and instructors that had largely ignored the dramatic conceptual changes that had taken place. The result is that many think of Pavlovian conditioning as an obsolete technical field that is intellectually stagnant.

My intention in this article is to show that this view is incorrect. First, I will review some of the changes that have occurred in Pavlovian conditioning in order to give the flavor of its contemporary form. I will argue that it is an intellectually challenging field, in which substantial and exciting progress has been made. Second, I will argue that conditioning...