Flashing anomalous color contrast

Abstract

A new visual phenomenon that we call flashing anomalous color contrast is described. This phenomenon arises from the interaction between a gray central disk and a chromatic annulus surrounded by black radial lines. In an array of such figures, the central gray disk no longer appears gray, but assumes a color complementary to that of the surrounding annulus. The induced color appears: (1) vivid and saturated; (2) self-luminous, not a surface property; (3) flashing with eye or stimulus movement; (4) floating out of its confines; and (5) stronger in extrafoveal than in foveal vision. The strength of the effect depends on the number, length, width, and luminance contrast of the radial lines. The results suggest that the chromatic ring bounding the inner tips of the black radial lines induces simultaneous color contrast, whereas the radial lines elicit, in conjunction with the gray disk and the ring, the flashing, vividness, and high saturation of the effect. The stimulus properties inducing the illusion suggest that flashing anomalous color contrast may be based on asynchronous interactions among multiple visual pathways.

Fig. 1

Three phenomena arising from radial lines: Ehrenstein illusion (top), anomalous brightness (middle), and scintillating luster (bottom). Depending on the size of the figures, it may be necessary to vary the viewing distance to optimize the effects described in the text.

Fig. 2

Flashing anomalous color contrast. The induced yellowish-green color is vivid, flashes with eye movements, floats out of its confines with stimulus movement, and is stronger in peripheral than in foveal vision.

Fig. 3

Flashing anomalous color contrast. Gray disks surrounded by green annuli are perceived as reddish flashing lights.

Fig. 4

Mean ratings plotted as a function of the number of radial lines. Here and in the following figures the calibration line denotes the mean standard deviation.

Fig. 5

Mean ratings plotted as a function of radial line length.

Fig. 6

Mean ratings plotted as a function of radial line width.

Fig. 7

Mean ratings plotted as a function of luminance contrast (log scale) between the radial lines and the background.