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Steven K. Shevell, Sherry X. Xian; Chromatic induction from grouping. Journal of Vision 2003;3(12):32. doi: 10.1167/3.12.32.
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© ARVO (1962-2015); The Authors (2016-present)
INTRODUCTION Typical demonstrations of chromatic induction have a test field within a uniform chromatic surround but natural scenes often have a surround composed of many different chromaticities. A new question arises with a complex surround: how do the various elements within it contribute to induction? While induction varies with physical features of the stimulus such as inducing light distance, size and saturation (Kirschmann's Laws, 1891), induction also may depend on perceptual grouping of fragments into distinct objects or groups. The present study examined whether local chromatic induction in one part of a scene carried over to a separate region belonging to the same perceptual group. METHODS A test square was presented on a background composed of many horizontal stripes alternating between two chromaticities, which appeared greenish and purplish. The test was centered on a border between two stripes, so its top half was on one chromaticity and its bottom half on the other. The appearance of the test square was measured by asymmetric color matching. The test's appearance was little affected by the chromatic stripes. Six horizontal “inducing bars” were added, all of which were positioned on either greenish or purplish stripes. The configuration of the 6 inducing bars plus the test square formed an ‘hourglass’ structure, so the test was grouped with the inducing bars. The stripes induced a substantial shift in the appearance of the inducing bars, in a direction away from the stripe chromaticity on which the bars were positioned. RESULTS & CONCLUSION. The color of the test shifted toward the appearance of the inducing bars, with which it was grouped. Moving all the inducing bars from greenish to purplish stripes shifted not only their appearance but also the appearance of the (invariant) test square. This demonstrated chromatic induction from grouping.
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