Chromatic detection and discrimination analyzed by a Bayesian classifier

Detection and threshold-level discrimination of Gabor patches were studied under the conditions of noise masking, in an attempt to isolate 'higher-ord er' or nonclassical color mechanisms. Detection contours in the equiluminan t plane of cone contrast space were measured by varying test chromaticity i n the presence of chromatic masking noise. Three equiluminant noise directi ons were used, in separate experiments. In the discrimination experiment, o bservers had to discriminate between pairs of stimuli that were fixed at th eir masked threshold contrasts. A Bayesian color classifier model was used to analyze the discrimination data, with no free parameters. There was no e vidence of nonclassical color mechanisms in either the detection or discrim ination data. (C) 2001 Elsevier Science Ltd. All rights reserved.