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Researchers of visual perception have long been interested in the perceived slant of a surface and in the gradients that purportedly specify it. Slant is the angle between the line of sight and the tangent to the planar surface at any point, also called the surface normal. Gradients are the sources of information that grade, or change, with visual angle as(More)
, for example , are known to be about 14,000 years old, but with the recently discovered paintings in the Grotte Chauvet, the origin of representational art appears to have been pushed back even further years ago if not longer. 1 Thus, these paintings date from about the time at which homo sapiens sapiens first appeared in Europe (Nougier, 1969). We should(More)
When an individual moves through a cluttered environment, he or she often fixates an object relatively near his or her path in the middle distance and uses pursuit eye movements to follow it while moving forward. On the basis of previous evidence, either motion fields or displacement fields around the fixated object--two alternative representations of the(More)
People find their way through cluttered environments with ease and without injury. How do they do it? Two approaches to wayfinding are considered: Differential motion parallax (DMP) is a retinal motion invariant of near and far objects moving against fixation; the information in optical flow (IOF) is a radial pattern of vectors, relying on decomposition of(More)
In three experiments we tried to mask the motions of human gait. We represented human walkers as a set of 11 computer-generated elements on a display monitor, moving as a nested hierarchy of motions that mimicked the motions of the head and m~jor joints. The walker was seen in sagittal view, facing either right or let~ and walking as if on a treadmill. On(More)
In natural vision, information overspecifies the relative distances between objects and their layout in three dimensions. Directed perception applies (Cutting, 1986), rather than direct or indirect perception, because any single source of information (or cue) might be adequate to reveal relative depth (or local depth order), but many are present and useful(More)
  • J E Cutting
  • 1987
Pictures and cinema seen at a slant present the optics of virtual objects that are distorted and inconsistent with their real counterparts. In particular, it should not be possible for moving objects on slanted film and television screens to be seen as rigid, at least according to rules of linear perspective. Previous approaches to this problem have(More)
When comparing psychological models a researcher should assess their relative selectivity, scope, and simplicity. The third of these considerations can be measured by the models' parameter counts or equation length, the second by their ability to fit random data, and the first by their differential ability to fit patterned data over random data. These(More)
The three-dimensional space around us is conveniently and reasonably Euclidean. Can we assume our perception of this space, and of objects in it, would follow suit? This assumption is quite natural, but empirical results suggest that it is also quite wrong, except in narrow circumstances. Perceptual space grades from being nearly Euclidean within a meter of(More)