The effect of US preexposure on conditioned taste aversion: lack of postconditioning recovery of the aversion.

Although the CS preexposure effect in CTA was once viewed exclusively as an acquisition failure, recent studies have suggested that the latent inhibition phenomenon is the result of retrieval impairment. This interpretive challenge is based on the unexpected finding that recovery of the aversion occurs over a long retention interval following conditioning (Kraemer, Lariviere, & Spear, Animal Learning and Behavior, 16, 185-190, 1988; Bakner, Strohen, Nordeen, & Riccio, Physiology & Behavior, 50, 1269-1272, 1991). This study examined whether a similar recovery occurs after US preexposure. Following preexposure to the US (LiCl), rats received a sucrose-illness pairing and were subsequently tested after either short or long training-to-test intervals. In contrast to the findings with the CS preexposure effect, US-preexposed subjects did not show a spontaneous increase in CTA following the long retention interval.