Facilitation of appetitive conditioning with naturalistic conditioned stimuli: CS and US factors

Adding limited female cues to a conditioned stimulus (CS) facilitates condi tioned male sexual responding. In two experiments, we examined the mechanis ms of this facilitation effect. The color of the female cues on the CS was varied in Experiment 1. Similarity between the CS plumage color and the col or of the live female (the unconditioned stimulus [US]) could only partiall y account for the results. The extent to which the facilitation effect repr esents a specialization of sexual behavior was examined in Experiment 2 by comparing conditioning with either food or copulation as the US. The CSs wi th female cues elicited more approach and grab responses regardless of whic h US was used. However, uniquely sexual conditioned responses (mounts and c loacal contacts) were enhanced only when sexual reinforcement served as the US. These findings suggest that the facilitation effect of female cues rep resents a general feature of appetitive behavior systems.