Pre-exposure to contrast selectively compresses the achromatic half-axes of color space

The gamut of perceived colors can be represented in a space with bright-dar k, red-green and blue-yellow axes. Pre-exposure to a field that changes per iodically over time in luminance or along one of the color axes reduces viv idness of colors along the entire axis [Webster and Mellon (1991) Nature, 3 49, 235-238]. But is it possible to reduce vividness or perceived contrast selectively for half-axes in color space? We assessed such selective compre ssion of the bright-dark axis using a task where subjects matched tests in a pre-adapted region to ones in an un-adapted region. Tests were bright or dark pinstripes on a gray background, and pre-exposure was to multiple drif ting pinstripes. Matches made after pl-e-exposure indicate a combination of symmetric and asymmetric compression, with more compression when adapting and test stimulus were similar in contrast polarity. (C) 2000 Elsevier Scie nce Ltd. All rights reserved.