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Crowding and surround suppression share many similarities, which suggests the possibility of a common mechanism. Despite decades of research, there has been little effort to compare the two phenomena in a consistent fashion. A recent study by D. M. Levi, S. Hariharan, and S. A. Klein (2002) argues that the two are unrelated because crowding effects can be(More)
Amblyopia ("lazy eye") is an impairment in visual acuity resulting from abnormal neural development in the visual cortex. We tested the responses of ten amblyopic and six normal observers to illusions of perceived orientation in textures of Gabor patches: the "Fraser illusion," the "phase illusion," and a "tilted chain" illusion. The illusory tilt of the(More)
The abundant literature on crowding offers fairly simple explanations for the phenomenon, such as position uncertainty or feature pooling, but convincing evidence to support these explanations is lacking. In part, this is because the stimuli used for crowding studies are usually letters or other complex shapes, which makes it hard to determine exactly what(More)
We investigated over what central area disparity in a random dot stereogram is integrated to stimulate an initial vergence response. Vergence was measured subjectively, with a forced choice dichoptic nonius vernier task following a brief (230 msec) stimulus presentation. Stimuli were random-dot stereograms showing a central circular disc of 12.5 min arc(More)
In the attentional blink [Raymond, J. E., Shapiro, K. L., & Arnell, K. M. (1992). Temporary suppression of visual processing in an RSVP task: An attentional blink? Journal of Experimental Psychology: Human Perception and Performance, 18(3), 849-860.], the second of two targets in a Rapid Serial Visual Presentation (RSVP) stream is difficult to detect and(More)
Our ability to align three Gabor patches depends upon their internal carrier orientation; we are better at aligning vertical or horizontal patches than oblique patches (Keeble and Hess, 1998). However, the tuning of alignment to patch orientation has not studied in detail. We measured the alignment of a vertical target with reference patches varying in(More)
In the Fraser phase-illusion [Popple & Sagi. Vision Research, 40 (2000) 873-878] rows of Gabor patches appear tilted because successive elements are shifted in phase. We measured this bias in global orientation judgment, while varying the number of patches in each row, and their separation. We found that illusory tilt increases with the number of patches,(More)
The twisted-cord illusion is a powerful demonstration of interaction between 1st-order (luminance-defined) and 2nd-order (contrast-defined) orientation processing. The perceived orientation of contrast-defined objects is pulled towards their 1st-order orientation content when the difference in orientation is small (Fraser effect), yet is pushed away from(More)