SPECTRAL BANDWIDTHS FOR THE DETECTION OF COLOR

The spectral properties of human color detection mechanisms were measu red using a noise masking technique that minimizes the possibility of off-axis looking and artifactually narrow estimates of bandwidth. Obse rvers were induced to use a single detection mechanism throughout a sp ectral bandwidth measurement by using sectored noise to mask a time-va rying signal of fixed chromatic properties. Sectored noise draws sampl es from sectors of variable width in the color plane, centered on the signal axis. Contrast thresholds for equiluminant signals that appeare d yellow, orange, red and violet were found to depend on the power of the noise, projected along the chromatic axis of the signal, but not o n the sector width of the noise. These results are consistent with the activity of spectrally broadband, linear detection mechanisms that ar e tuned to the signal color directions tested. (C) 1998 Elsevier Scien ce Ltd. All rights reserved.