learned flavor preference persists despite the extinction of conditioned hedonic reactions to the cue flavors

摘要

Learned flavor preferences can be strikingly persistent in the face of behavioral extinction. Harris, Shand, Carroll, and Westbrook (2004) suggested that this persistence may be due to flavor preference conditioning’s producing a long-lasting change in the hedonic response to the conditioned stimulus (CS1) flavor. In the present study, the CS1 flavor was presented in simultaneous compound with 16% sucrose, whereas the CS2 flavor was presented with 2% sucrose. During subsequent two- and one-bottle tests, the CS1 and CS2 flavors were presented in 2% sucrose. Hedonic reactions during training and test were assessed using an analysis of the microstructure of licking behavior. Conditioning resulted in greater consumption of the CS1 than of the CS2 that did not extinguish over repeated two- and one-bottle tests. The mean lick cluster size was higher for the CS1 than for the CS2 only on the first cycle of tests. Since lick cluster size can be used as an index of stimulus palatability, the present results indicate that although the hedonic reaction to the CSs did change, this was not maintained across repeated tests. Thus, changes in the hedonic response to the conditioned flavors cannot explain the resistance to the extinction of learned flavor preferences.