Is neural binding of color and form required for perception of a
unified colored object? Individual cells selectively tuned to both color
and orientation are proposed to moot the binding problem. This study
reveals perceptual misbinding of color, thereby revealing
separate neural representations of color and form followed by a subsequent
binding process. Low luminance-contrast, rivalrous chromatic gratings were
presented dichoptically. Each grating had alternating chromatic and gray
stripes (e.g., red/gray in the left eye, green/gray in the right
eye). Observers viewed the two rivalrous, 2 cpd gratings for 1 min. The
duration of exclusive visibility was measured for four percepts: left-eye
stimulus, right-eye stimulus, fusion of the two colors, or a two-color
grating (e.g. a red/green grating). The percept of a two-color grating
(misbinding) was observed with Michelson luminance contrast in the grating
up to 20%. In general, for a given level of luminance contrast either
misbinding (low luminance contrast) or color mixture (high luminance
contrast) was observed, but not both of them. The perceived two-color
gratings show that two rivalrous chromaticities are both represented
neurally when color and form are combined to give a unified percept.
“Resolution” of competing chromatic signals from the two eyes
is not restricted to color dominance and color mixture. The transition
from misbinding to color mixture by increasing luminance contrast shows
that luminance edges have an important role in correct localization of
color.