Some unresolved issues in perceptual learning.

Perceptual learning has been studied extensively using a procedure in which subjects (involving both humans and nonhuman animals) are exposed to two similar stimuli (to be referred to as AX and BX, where A and B represent distinctive features and X the features they hold in common), prior to a test of their ability to discriminate between AX and BX. Performance on the discrimination is found to be enhanced by this procedure, particularly if the preexposure arrangement involves intermixed presentations of AX and BX (a regime that might be expected to facilitate comparison of the stimuli). This perceptual learning effect has generated a range of theoretical interpretations that have focused, for the most part, on how exposure to a stimulus (or feature of a stimulus) can change its effectiveness, by which is meant its ability to command processing and to control responding. But a consensus is difficult to achieve, given that some aspects of what must be explained remain uncertain. Three issues are discussed here: Does appropriate exposure to the stimuli reduce the effectiveness of the common, X, elements? Does exposure enhance the effectiveness of the unique (A and B) elements? Are any such effects enhanced by the opportunity to compare the stimuli? It will require further experimental work to answer these questions, but raising them may promote this and thus facilitate achieving a satisfactory theoretical analysis. (PsycInfo Database Record (c) 2021 APA, all rights reserved).