Dissociative storage systems in human evaluative conditioning.

There is strong evidence in the literature that human evaluative conditioning can occur in the absence of conditioned stimulus-unconditioned stimulus (CS-UCS) (contingency) awareness, yet this evidence has been disputed on methodological grounds. The current study replicated evaluative conditioning with some procedural modifications, including the use of mental imagery as a way of associating a UCS with a CS picture, and tests of long-term retention of contingency memory and preference ratings. While the acquisition of evaluative responses was found to be significantly dependent upon contingency awareness (especially for pairings with unpleasant images), preference ratings for the CSs 2 months later were still biased by their associated images but subjects could not recall the image for more than 90% of the pictures. These results demonstrate that performance of the evaluative response can occur independently of conscious memory for the contingencies involved, provide further support for a model which supposes the existence of dissociative storage structures in human classical conditioning.