Perspective and perception: vision and touch

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Pictures are one of our most effective ways to communicate information. But their uses remain mysterious and their potential is still unknown. How do we perceive and represent 3D space? Remarkably, blind people use perspective to solve this problem, not just the sighted. But how? Both vision and touch must have a way of responding to the features of perspective pictures. Vision is often correct in estimating the shape of middle-distance objects sitting on the ground. But since the geometry of perspective was first devised it has been obvious that there are striking limits to the perspective pictures that perception can handle. Distant tiles on a floor can look stubby. Tiles on the sides of pictures can look very stretched; that is, on the margins of perfect perspective pictures, forms appear distorted, highly distended. This is why cameras for everyday only use contain narrow-angle lenses, not wide-angle lenses that reveal the marginal distortions. These effects may all be caused by perception's underestimation of foreshortening. The same effects may occur in touch, as well as vision, as sighted-blindfolded and truly blind people point to a row of objects receding into the distance.