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.The distinction between stimulus identification and response selection is generally considered as a basic framework for the analysis of performance in speeded classification tasks. The operation of stimulus identification provides a categorization of the stimulus as one of the possible alternatives on the basis of the physical stimulus properties. The operation of response selection then provides a selection of one of the possible responses on the basis of the information associated with the corresponding category (cf. Smith, 1968).The distinction between stimulus identification and response selection can also be applied to the analysis of performance in continuous visual search tasks. In the first operation, a list item, (e.g., a letter) is identified. In the second operation, information about the item's status is retrieved (target vs.