The effects of satiation after first- and second-order appetitive conditioning in rats.

Rats received first- and second-order conditioning based on a food unconditional stimulus (US). The effects of postconditioning satiation on the performance of detailed behavioral components of general activity evoked by first- and second-order conditional stimuli (CSs) were then assessed in extinction tests. Satiation reduced the frequency of all components of general activity evoked by first-order CSs but had little or no effects on behaviors evoked by second-order CSs. These results are consistent with earlier suggestions that first- but not second-order conditional responding is mediated by a representation of the US and that a major effect of satiation is to devalue that representation.