Was Pavlov an Equal Opportunity Conditioner?

Ivan PavlovThe spring 2007 issue of the Journal of Mind and Behavior, 28 (2), contains an article on whether the famed Russian physiologist Ivan Pavlov would have agreed with American behaviorists of the mid-20th century that virtually any sensory object has the equivalent potential as a conditioned stimulus. The claim, dubbed by Seligman (1970) as “equivalence of associability,” was often attributed to Pavlov, and was a virtual article of faith among American behaviorists until studies such as those by the Brelands (1961) and by Garcia and Koelling (1966) demonstrated that different animals have different propensities to associate certain kinds of CS with certain classes of response.

By contrast, in the article “Pavlov and the Equivalence of Associability in Classical Conditioning,”

although Pavlov held that most cues can be made into effective CSs, he did not claim that different classes of cues have the same potential for conditioning. That is, he endorsed weak equivalence but not strong equivalence of associability: he could hardly be regarded as an apostle of the full, undifferentiated version of the equivalence of associability of cues in classical conditioning.

The article also investigates some of the social and philosophical reasons that researchers such as Garcia and Koelling had such trouble publishing a result that now seems so plainly obvious to so many — that different species of animal with different evolutionary histories are going to be differentially responsive to different phenomena, and why the behaviorist community was so strongly arrayed against such a conclusion in the 1960s.

The full abstract of the article is copied below.


Breland, K., & Breland, M. (1961). The misbehavior of organisms. American Psychologist, 16, 681-684.

Garcia, J., & Koelling, R. A. (1966). Relation of cue to consequence in avoidance learning. Psychonomic Science, 4, 123-124.

Seligman, M. E. P. (1970). On the generality of the laws of learning. Psychological Review, 77, 406-418.


The discovery of selective associability of cues in classical (Pavlovian) conditioning has often been treated as an embarrassment to Pavlov, because he has been represented as a proponent of the “equivalence of associability of cues.” According to that doctrine, except for the influence of differences in stimulus intensity, all environmental stimuli are equally susceptible to becoming conditioned stimuli (CSs) if they are arranged in a suitable time-relation to any effective unconditioned stimulus (US). The current paper asks whether Pavlov explicitly made such a claim and, if not, whether he could have endorsed equivalence of associability. Scientific controversy, the role that “the classics” play in scientific specialties, and the emblematic standing of the founding figures of a discipline or specialty constitute a framework for discussion of Pavlov’s stand on the equivalence of associability.

About Christopher Green

Professor of Psychology at York University (Toronto). Former editor of the Journal of the History of the Behavioral Sciences. Creator of the "Classics in the History of Psychology" website and of the "This Week in the History of Psychology" podcast series.