EFFECT OF LUMINANCE ON COLOR-PERCEPTION OF PROTANOPES

Small-field color-naming performance of two protanopes over a 4-log lu minance range was impoverished in comparison with that of normal trich romats, and was more strongly affected by changes in luminance. At 200 cd/m(2) responses to mid-spectral lights were dominated by 'yellow'; with lowering luminance, 'green' and 'red' were increasingly used. In the color spaces derived from these data the first two dimensions for trichromats are red-preen and yellow-blue; those of the protanopes app ear to be brightness and 'red-blue'. In the protanopes' color space th e greater separation of stimuli at 0.2 cd/m(2) suggests that with low luminance their color discrimination improves. (C) 1998 Elsevier Scien ce Ltd. All rights reserved.