Re-examination of the poisoned-partner effect with the two-bottle testing method.

Revusky, Coombes and Pohl (Animal Learning and Behavior 10 (1982) 83-90) suggested that poisoned conspecifics function as aversive unconditional stimuli (USs) for rats (the poisoned-partner effect). The present study re-examines this effect with the two-bottle testing method. Rats were first given saccharin and later exposed to a poisoned conspecific. They exhibited an aversion to saccharin in the subsequent tests involving a choice between saccharin solution and water. Furthermore, the subjects that were only exposed to the poisoned conspecific later avoided saccharin. The poisoned-partner effect, therefore, can also be explained by sensitization. This finding suggests that poisoned conspecifics are simply salient stimuli that attract the rat's attention, rather than aversive USs of food aversion learning for rats.