Visual Illusions - Binocular Cues

The display of observer-centered binocular cues on a Visual Display Terminal is very difficult. And even more difficult for the viewer of these illusions. A good example of these illusions are the Magic Eye book series. There are also many computer program that can generate these illusions to be printed and not viewed on the screen.
Binocular DisparityThe images received by the two eyes, located at slightly different points in space, are disparate. The degree of disparity provides a basis for the judgment of distance (Wickens, 1992).
ConvergenceThe "cross-eyed" pattern of the eyes, required to focus on objects as they are brought close to the observer, is necessary to bring the image onto the detail-sensitive retina of both eyes. Proprioception from the muscles of the eyes to the perceptual centers of the brain inform the brain of the degree of convergence and therefore of the object's distance (Wickens, 1992).
AccommodationLike convergence is a cue provided to the brain by the eye muscles. The cue in this case is from the muscles that adjust the shape of the lens to bring the image into focus on the retina (Wickens, 1992).

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Dave Crow

Last updated: Nov28,1995: Dave Crow