The Role of Counter-conditioning in the Extinction of Conditioned Taste Aversions

Abstract

The experiments reported in this thesis attempted to examine the influence of thirst on the extinction of taste aversions in rats. Differences in the amount of stimulus exposure and deprivation state between groups were controlled for. The first experiment presented two novel flavours twelve times to rats when either thirsty or sated. A preference for the flavour presented when thirsty was established. The next three experiments examined whether this preference would accelerate the extinction of a taste aversion, by first pairing a novel flavour with lithium and then presenting the conditioned flavour when rats were either sated or thirsty. No evidence of accelerated extinction was found. The final two experiments examined whether the associatively-activated representation of sucrose could function to extinguish a taste-aversion to that sucrose without presenting sucrose itself. No evidence of representation-mediated extinction was found despite evidence that the context was associated with sucrose. The results indicate that the extinction of conditioned taste aversions is not influenced by counter-conditioning due to thirst relief, and extinction of such aversions appears to be due to similar processes as other forms of conditioning.