Gideon P. Caplovitz

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Contour curvature (CC) is a vital cue for the analysis of both form and motion. Using functional magnetic resonance imaging, we localized the neural correlates of CC for the processing and perception of rotational motion. We found that the blood oxygen level-dependent signal in retinotopic area V3A and possibly also lateral occipital cortex (LOC) varied(More)
OBJECTIVE We describe q-sequence deconvolution (QSD), a new data acquisition/analysis method for evoked-responses that solves the problem of waveform distortion at high stimulus repetition-rates, due to response overlap. QSD can increase the sensitivity of clinically useful evoked-responses because it is well known that high stimulus repetition-rates are(More)
A new motion illusion, "illusory rebound motion" (IRM), is described. IRM is qualitatively similar to illusory line motion (ILM). ILM occurs when a bar is presented shortly after an initial stimulus such that the bar appears to move continuously away from the initial stimulus. IRM occurs when a second bar of a different color is presented at the same(More)
When individually moving elements in the visual scene are perceptually grouped together into a coherently moving object, they can appear to slow down. In the present article, we show that the perceived speed of a particular global-motion percept is not dictated completely by the speed of the local moving elements. We investigated a stimulus that leads to(More)
UNLABELLED Unlike the motion of a continuous contour, the motion of a single dot is unambiguous and immune to the aperture problem. Here we exploit this fact to explore the conditions under which unambiguous local motion signals are used to drive global percepts of an ellipse undergoing rotation. In previous work, we have shown that a thin, high aspect(More)
Form analysis subserves motion processing in at least two ways: first, in terms of figural segmentation dedicated to solving the problem of figure-to-figure matching over time, and second, in terms of defining trackable features whose unambiguous motion signals can be generalized to ambiguously moving portions of an object. The former is a primarily ventral(More)
The authors are in the Department of Psychology and Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey, USA. e-mail: or people such as radiologists and pilots, whose professions often depend on being able to perceive and recognize objects at low contrast. For example, a radiologist(More)
Identical local image motion signals can arise from countless object motions in the world. In order to resolve this ambiguity, the visual system must somehow integrate motion signals arising from different locations along an object's contour. Difficulties arise, however, because image contours can derive from multiple objects and from occlusion. Thus,(More)
We present a new multistable stimulus generated by continuously rotating an ellipse behind four fixed occluders. Despite the stimulus remaining constant, observers can alternate between one of four percepts: (1) a continuously morphing cross; (2) two independent perpendicular bars oscillating in depth; (3) a rigidly rotating ellipse observed behind the(More)
The Alternating Brightness Star (ABS) is an illusion that provides insight into the relationship between brightness perception and corner angle. Recent psychophysical studies of this illusion have shown that corner salience varies parametrically with corner angle, with sharp angles leading to strong illusory percepts and shallow angles leading to weak(More)