Locus of the effect of specific practice in continuous visual search

Specific practice in a visual search task can result either in a selective elaboration of the feature lists of the task stimuli or in a selective emphasis of their status within the task (targets vs. nontargets). According to the first explanation, which is related to the differentiation principle of perceptual learning, specific practice enhances the operation of stimulus identification. According to the second explanation, which is related to the enrichment principle of perceptual learning, it enhances the operation of response selection. Evidence from two transfer experiments with a reversal paradigm argues in favor of the second view, at least for tasks with easily codable letter stimuli. The results are discussed in the framework of a recent model of information integration in visual search.