Abstract
PURPOSE Perceptual misbinding of color during binocular rivalry reveals separate neural representations of color and form followed by a neural binding process (Hong & Shevell, Visual Neuroscience, 2006). During misbinding of color, the neural representation of color from a suppressed form is expressed within a region of the dominant form. The study here examined how color is misbound to a non-retinotopic location and considered how the neural representation of location relates to perceptual binding of color to form.
METHOD A 2 cpd square-wave vertical grating was presented to one eye and a tooth-shaped vertically oriented grating (top half of grating phase-shifted right by one-half cycle relative to bottom half) to the other eye for 90 seconds. A grating with luminance-contrast (e.g. a red/black grating) was presented to one eye, and an isoluminant grating (e.g. a green/white grating) to the other eye. The exclusive visibility time was measured for the percept of each eye's stimulus alone (dominance) and for a two-color vertical or tooth-shaped grating (e.g. a perceived red/green grating). The two different forms (vertical vs tooth-shaped) distinguished whether misbinding was perceived in the form with luminance contrast or the form at isoluminance.
RESULTS With luminance contrast of 75% or more, misbinding of color was perceived frequently within the isoluminant form but very rarely within the luminance-contrast form.
CONCLUSION The results indicate misbinding occurs within the form with a weak neural representation of location. Misbinding of a chromatic signal from the suppressed luminance-contrast form shows that location information provided by luminance-contrast edges does not inhibit binding the color to a non-retinotopic region within the dominant isoluminant form. Suppression of form may also suppress the neural representation of location but an open question is whether form and location are represented separately.
Supported by PHS grant EY-04802