Assessing a new analysis of contingent color aftereffects

McCollough (1965) demonstrated that exposure to colored vertical and horizontal grids results in a complementary color aftereffect contingent upon bar orientation. For example, after an induction period consisting of presentations of a grid made of green and black horizontal bars alternating with another grid made of red and black vertical bars, subjects report negative color aftereffects contingent upon grid orientation; they report that achromatic horizontal grids appear pink, and achromatic vertical grids appear green. McCollough’s discovery inspired a considerable amount of research concerning contingent color aftereffects (CCAEs) (McCollough, 1965). Results of this research indicate that CCAEs are very robust, being detectable for weeks after induction (e.g., Jones and Holding, 1975). Although most CCAE research has used adult humans, the phenomenon has been observed in young children (e.g., Meyer et al., 1982), monkeys (Macquire et al., 1980), and pigeons (Roberts, 1984). A number of theoretical interpretations of CCAEs have been proposed since the publication of McCollough’s now classic paper (McCollough, 1965). Recently, Bedford (1995) presented a new account of CCAEs, which she termed a ‘perceptual learning theory". She claimed that her account explained ‘findings difficult to account for in other interpretations including which stimuli can successfully lead to contingent after-effects, the outcome of correlation manipulations, and why the effect exists at all’ (p. 253). Bedford’s account is ingenious and comprehensive, and her approach differs from other current theoretical positions: e.g., edge-detection (e.g., Broerse and O’Shea, 1995), associative (e.g., Allan and Siegel, 1986, 1993; Murch, 1976; Siegel and Allan, 1992), and error-correction (e.g., Dodwell and Humphrey, 1990, 1993). Moreover, Bedford attempts to integrate CCAEs and prism adaptation within a single theoretical framework. We present a critical appraisal of Bedford’s account of CCAEs. Although her account is admirably creative and integrative, it makes predictions that are not in