Luminance is processed linearly in apparent motion, vernier offset and stereo depth

<p>PURPOSE Two potential motions occur when a black and white bar suddenly exchange luminances. The bar differing most from the surround luminance is seen as moving (Anstis & Mather, 1985). We now extend this result to stereo and Vernier acuity. METHOD Light and dark bars produced opposite motions, vernier offsets or stereo on a grey surround (see Fig.) 5s measured the indifference luminance level of the surround at which motion, Vernier offset or depth were ambiguous or minimal. RESULTS A linear visual response to luminance would put the indifference surround luminance halfway between the luminances of the two bars and the data should lie on the plane surface (x+y)/2. A visual logarithmic transform of input luminance would put the data on the convex-upwards curved surface â??(xy). The motion results (below) fit the plane best, so luminance processing is linear. All 3 tasks gave similar results. CONCLUSION Input luminance is processed linearly for all three tasks, with no log transform.</p>