Color vision in the peripheral retina. II. Hue and saturation.

Hue and saturation of spectral lights were measured (direct scaling) in the fovea and at 45 degrees in the periphery; all lights were of equal photopic retinal illuminance (1200 trolands). At each retinal location both large and small targets were used. As shown by previous studies, small peripheral targets appear desaturated and of uncertain hue, except long wavelengths which appear red. However, if target size is increased, saturation increases and a full range of hues is seen; the hue functions for large peripheral targets are comparable to foveal ones for very small targets. From a modified form of color matching, it was concluded that the color deficiency in the periphery is more tritanlike than deutanlike; this is strengthened by the observation, that, for small peripheral targets, hues are generally apportioned between two hue categories and the change from one to the other is at about 580 nm.