Inhibition and Mediated Activation Between Conditioned Stimuli: Parallels Between Perceptual Learning and Associative Conditioning

This series examines the associative basis of inhibitory perceptual learning. Four experiments demonstrate that inhibitory perceptual learning, like Pavlovian conditioned inhibition, is affected by manipulating the number of training trials. Specifically, many interspersed XB/AB training trials (in which letters represent initially neutral stimuli such as tones, clicks, and flashing lights) followed by A-US pairings caused X to act like a conditioned inhibitor (Experiment 1), which is presumed to suggest that an inhibitory association between conditioned stimuli X and A had been formed (i.e., inhibitory perceptual learning). Conversely, few XB/AB training trials followed by A-US pairings produced conditioned responding to X (Experiment 2), which suggests that an excitatory association between X and A had been formed. Additionally, associations with the common element, B, appear to play an inconsistent role across inhibitory and excitatory perceptual learning situations, as extinction of B attenuated excitatory (Experiment 3) but failed to have an influence after inhibitory (Experiment 4) pretraining. The viability of several different accounts of perceptual learning is discussed in light of these observations.