Abstract

We have compared color discrimination thresholds for long-wavelength spectral lights presented to the fovea and to the peripheral retina. Results obtained in the fovea are similar to those obtained by other investigators. Threshold increases as the test wavelength is increased. The slope of the threshold-versus-wavelength function decreases as the stimulus field is moved further into the periphery. Peripheral thresholds are significantly higher on a blue background bright enough to desensitize rods, but they are not bright enough to raise foveal thresholds, suggesting that rod signals contribute to the peripheral thresholds. However, the shapes of the threshold-versus-wavelength functions obtained on the background differ in the fovea and the periphery, suggesting that differences between foveal and peripheral functions are not produced entirely by rods. Foveal and peripheral functions are similar in shape if the peripheral thresholds are obtained with a larger test field.

© 1990 Optical Society of America