A RESPONSE-TIME THEORY OF SEPARABILITY AND INTEGRALITY IN SPEEDED CLASSIFICATION

A theoretical framework is developed for the speeded classification tests of perceptual separability and integrality, which were popularized by Garner (1974, The processing of information and structure, New York: Wiley). The theory generalizes general recognition theory (Ashby & Townsend, 1986, Psychological Review 93, 154-179) by incorporating the assumption that response time decreases with the distance between the perceptual representation of a stimulus and the decision bound. We show that if decisional separability holds and if there are no stimulus context effects, then the filtering and redundancy tasks provide good tests of separability and integrality. However, if the subject responds optimally then redundancy gains are likely, regardless of whether the dimensions are integral or separable. Context effects also may invalidate both tests. Finally, we propose a new test of separability that can be performed on data collected in the filtering task, which is not susceptible to context effects or to changes in the subject's decision strategy. (C) 1994 Academic Press, Inc.