Verbal overshadowing of perceptual discrimination.

We examined effects of verbal interference on a perceptual discrimination task. Participants were presented with a series of faces, described (or did not describe) an additional face, and then made face/ nonface decisions to both the original faces and new faces, intermingled with nonfaces. This enabled us to examine the effect of making a verbal description, relative to an unrelated filler task in a control condition, on the perceptual discrimination of faces seen for the first time and faces encountered previously, and also on repetition priming (i.e., the facilitative effect of an encounter with a stimulus on subsequent processing of the same stimulus). Verbalization interfered with performance on both new and studied faces, but it did not interfere with priming. We argue that verbalization encouraged a relatively long-lasting shift (over a number of trials) toward greater visual processing of individual facial features at the expense of more global visual processing, which is generally beneficial for the recognition of faces and important for discriminating faces from nonfaces in the face decision task.