Context-US Associations Rather Than Occasion Setting in Taste Aversion Learning

Abstract

Two experiments using a discriminative flavor-aversion procedure with rats analyzed the possible role of the contextual stimuli as an occasion setter. In Experiment 1, contextual control of the fluid ingestion was observed in that rats reduced consumption of a flavor in a context in which the fluid was paired with lithium chloride (LiCl) but did not reduce fluid ingestion in another context never paired with the lithium. Furthermore, significantly less consumption in the non-poisoned context was observed when a nonconditioned flavor was tested. In Experiment 2, the conditional control of flavor consumption survived even when the associative strength of the paired-lithium context had been extinguished by exposing the animals to water in the contexts after discriminative training. Extinction of the excitatory strength of the training flavor eliminated, however, the differential consumption. The results are interpreted as evidence that contextual control of performance in taste aversion learning is mediated by context-US associations. Alternative accounts in terms of occasion setting by contextual cues and configural conditioning are discussed.