Role of remote adaptation in perceived subjective color.

Light adaptation to illumination that is presented peripherally changes the subjective color of a central Benham disk stimulus. In our experiments we kept the peripheral illumination achromatic and remote (not even adjacent to the test stimulus). Using a high-frame-rate monitor, we produced the subjective color stimulus, to our knowledge for the first time, on a computer screen in emulation of the Benham disk programs. The resulting changes in the perceived subjective color were as follows: (1) Remote adapting illumination caused a dramatic shift in the perceived subjective color with a span from red to green; (2) there was a trade-off dependence between the area and the intensity of the remote adapting illumination with respect to the perceived color of the test stimulus; (3) the effect of the remote adaptation showed no interocular interaction. This finding suggests that the effect is elicited from a low-level stage in the visual pathway. In addition, we were able to approximate experimentally the spatial profile of the contribution of the remote illumination through the shift in the perceived color. We also found an opposite general trend of color shifts that occurred when either the central stimulus luminance or the remote illumination was increased. A suggested model for the reversed color shifts trend is discussed.