The elusiveness of evaluative conditioning

Evaluative conditioning (EC) is an important variant of Pavlovian conditioning in which the outcome is a change in affective response to the conditioned stimulus (CS). It is the best extant account, with evidence, for affective change in humans. Good laboratory models are available. This paper reviews a set of findings which suggest that the actual occurrence of EC, and its magnitude, varies widely in both real world and laboratory situations. Attention to known parameters of Pavlovian conditioning may account for some, but not all, of the failures and successes. Six empirical studies on humans are described; two document frequent failures of EC to occur in real world situations where the Pavlovian conditions for development of animal phobias or taste aversions are present, two are real-world experiments in which no evidence for EC is obtained, and two are laboratory failures to produce EC, by pairing neutral odor CSs with a variety of unconditioned stimuli (USs). We suggest that there are important, not understood factors, that modulate the appearance of EC, and that for both theoretical and applied reasons, these factors should be identified. (C) 1998 Academic Press.