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A colored line flanking a darker border will appear to assimilate its color onto the enclosed white area over distances of up to 45 deg (the Watercolor Effect). This coloration is uniform and complete within 100 ms. We found that thin (6 arcmin), winding inducing lines with different contrasts to the ground are generally more effective than thick, straight,(More)
With strict fixation, a small uniform target of medium contrast, placed at 10 deg eccentricity, faded much faster when presented on a dynamic random noise background than on either a static random noise background or a uniform background of the same luminance. Time to first disappearance was between 10 and 16 sec when the background was dynamic, 26 sec when(More)
When a dark chromatic contour delineating a figure is flanked on the inside by a brighter chromatic contour, the brighter color will spread into the entire enclosed area. This is known as the watercolor effect (WCE). Here we quantified the effect of color spreading using both color-matching and hue-cancellation tasks. Over a wide range of stimulus(More)
Psychophysical research on the Hermann grid illusion is reviewed and possible neurophysiological mechanisms are discussed. The illusion is most plausibly explained by lateral inhibition within the concentric receptive fields of retinal and/or geniculate ganglion cells, with contributions by the binocular orientation-specific cortical cells. Results may be(More)
Previous work showed that adapting to low spatial frequency gratings (below 1.5 cycles/degree) may cause maximal spatial adaptation at a significantly higher spatial frequency. It has been suggested that there are no adaptable spatial-frequency channels tuned to below 1.5 c/deg. Contrary to this view, we found that adaptation and masking with low spatial(More)
The watercolor effect (WCE) is a phenomenon of long-range color assimilation occurring when a dark chromatic contour delineating a figure is flanked on the inside by a brighter chromatic contour; the brighter color spreads into the entire enclosed area. Here, we determined the optimal chromatic parameters and the cone signals supporting the WCE. To that(More)
Classical receptive-field concepts have been used to explain local perceptual effects such as border contrast and Mach bands, but are not sufficient to explain global perceptual effects. Examples are the perception of illusory contours, area contrast, color constancy, depth planes, coherent motion and texture contrast. These diverse effects require(More)
We have measured the perceptive field, the psychophysical correlate of the physiologically determined receptive field, in man and monkey. Measurements were made using the Hermann grid illusion and the Westheimer paradigm. The following results were found: First, in both man and monkey, the size of perceptive fields and field centers increases from the fovea(More)
We determined how much motion coherence was needed to detect a target group of four moving dots in a dynamic visual noise (DVN) background. The lifetimes of the trajectories of the target and that of the noise dots were the same. In addition to parallel trajectories and collinear dot arrangements, divergent, convergent, or crossing trajectories and(More)
Gestalt psychologists in the early part of the century challenged psychophysical notions that perceptual phenomena can be understood from a punctate (atomistic) analysis of the elements present in the stimulus. Their ideas slowed later attempts to explain vision in terms of single-cell recordings from individual neurons. A rapprochement between Gestalt(More)