DIFFERENTIAL INFLATION WITH SHORT AND LONG CS-US INTERVALS - EVIDENCEOF A NONASSOCIATIVE PROCESS IN LONG-DELAY TASTE AVOIDANCE

Three experiments were performed to investigate the learning process u nderlying the phenomenon of long-delay taste conditioning. An associat ive model views taste avoidance as due to a conditioned stimulus-uncon ditioned stimulus (CS-US) associative structure, despite the long inte rval interposed between the flavor and illness. A nonassociative accou nt of this avoidance behavior posits that avoidance stems from the int eraction of two nonassociative processes: habituation of neophobic avo idance to a novel taste, and the poison-induced dishabituation of this process. A postconditioning inflation manipulation was used to discri minate between these two views. It has been demonstrated that enhanced responding with a US inflation manipulation depends, in part, on a pr eviously conditioned association. Therefore, if long-delay taste avoid ance arises from nonassociative processes, an inflation manipulation s hould not affect conditional responding. Experiment I demonstrated a d elay of reinforcement effect, enhanced avoidance of saccharin in the i mmediate/inflation group, and no effect of inflation in the delay grou p and sham controls. Experiment 2 revealed that this differential effe ct of inflation is not due to absolute differences in the strength of the avoidance response. In Experiment 3, we investigated a potential a ssociative learning mechanism that could account for the differential inflation effect. Together, the present results support the various pr edictions of a nonassociative account of long-delay taste avoidance.