Potentiation and overshadowing in pigeons

Abstract The present experiments investigated the relationship between potentiation and overshadowing in toxicosis conditioning in pigeons. In contrast to other experiments with these animals, Experiment 1 demonstrated that a compound consisting of a flavor and a visual cue did not lead to potentiation of visually mediated avoidance. Instead, the visual cue overshadowed flavor. Subsequent experiments examined factors that were responsible for these results. Experiments 2 and 3 indicated that reducing the intensity of eitehr the visual stimulus or the toxic US resulted in flavor-potentiated avoidance of the visual cue. Experiments 4A and 4B revealed that the manipulations used in Experments 2 and 3 not only supported potentiation, but eliminated overshadowing of flavor by visual cues. The implications of these data for theories of potentiation and overshadowing were discussed.