Abstract
By investigating the interactions between binocular rivalry and filling-in, it may be possible to gain insight into how selective and constructive visual mechanisms interact to determine the outcome of conscious perception. Previously, we have shown that visual phantoms lead to neuronal filling-in of activity in V1 and V2, which can be dynamically gated by rivalry suppression (Meng, Remus & Tong, Nature Neuroscience, 2005). Here, we used psychophysical methods to study the temporal dynamics of filling-in by using flash suppression to trigger the phenomenal suppression or appearance of visual phantoms. In one condition, two vertical phantom-inducing gratings (separated by a horizontal gap) were presented to one eye for several seconds, followed by a dichoptic mask that consisted of two horizontal gratings presented to corresponding locations of the other eye. Observers reported when the visual phantom disappeared. In the opposite condition, two horizontal gratings were followed by two vertical phantom-inducing gratings, and observers reported when the phantom appeared. Stimulus contrasts and durations were adjusted to maximize dichoptic masking, and the gap size varied from 2–5 degrees. Although the onset of vertical grating masks eventually led to phantom filling-in, more time was required for filling-in to occur across larger gaps. In contrast, the horizontal masks led to equally rapid suppression of the visual phantom, independent of gap size. This asymmetry in the time required for perceptual completion and suppression of visual phantoms suggests that mechanisms involved in rivalry suppression precede those involved in phantom filling-in.
Research support: NEI R01-EY14202 to FT