ABSTRACT
The most perverse feature of stimulus-response theories has always been their claim that knowledge about the consequences of actions and about the predictive implications of stimuli plays no role in the genesis of conditioned behavior. The natural interpretation of conditioning is that an animal comes to expect the reinforcer following either an established conditioned stimulus or an instrumental action and that such expectations act as causal agents in performance. In one form or another this position was vigorously defended throughout the heyday of stimulus-response theory by Tolman (1932, 1951, 1959) and his collaborators, but by the 1950s the parties to the dispute appeared to despair of a resolution with the result that the question of “what is learned” came to have less and less prominence in discussions of conditioning. Some with positivist inclinations (e.g., Kendler, 1952) abandoned the issue altogether because it was thought to be closed to empirical resolution (but see Ritchie, 1953, for an interesting rejoinder), whereas others (e.g., Thistlethwaite, 1951) were disillusioned by the variability of the empirical evidence.
