In defense of intraperceptual theories of attention.

A distinction is drawn between intraperceptual and extraperceptual theories of attention. Only the former class allows for the selective modulation of amount of nonconscious, perceptual processing of concurrent stimuli. The adequacy of intraperceptual theory has been questioned on the basis of diverse empirical findings. This literature is critically examined and is considered inconclusive partly because of the lack of an appropriate measure of amount of perceptual processing. A new experiment that attempts to provide such a measure is reported. Subjects detected names of states of the United States in dichotically presented lists. Subjects either could focus on just one list (relevant list) or had to divide their attention between the two lists. Amount of perceptual processing of a word (e.g., voice or titre) was measured in terms of the extent to which it primed subjects' interpretations of a visually presented homograph (e.g., spoke). Priming potency of words was greatest in the relevant list and was least in the other list. The data support a broad version of intaperceptual theory that allows for birth perceptual facilitation of relevant stimuli and perceptual suppression of irrelevant stimuli.