TACTILE PERCEPTION IN THE VISUALLY IMPAIRED
This part of the book is about blindness and perception. While the number of totally blind people is relatively small, the number of visually impaired individuals is much larger. If we include all of those people with a visual defect, the number is tremendous. Visual problems increase with aging. If we are lucky enough to reach old age (> 65), about 95% of us will wear corrective lenses ( Morse, Silberman, & Trief, 1987). Many of these individuals will have low vision when they remove their eyeglasses. Those fortunate few with "normal" vision still have poor visual acuity under conditions of very low light or peripheral vision.
The aim of researchers in this area is to understand tactual and spatial perception in the blind person. Some researchers have been interested in the study of perception in blind people primarily because of a concern with understanding blindness. Many others have focused their research on what these experiments tell us about perception per se. Various research strategies are in use, but the most common has involved comparisons of the sighted with congenitally blind and late blind persons. The congenitally blind individual has never seen and must develop an understanding of space via the sense of touch. Late blind people have benefited from visual experience. Consequently, their use of haptics will be "colored" by visual imagery and early visual experience. Most researchers have assumed that we can learn a great deal about the sense of touch by comparing the haptic performance of sighted and congenitally blind people.
It is far too easy to confuse the issues of the ability of blind subjects versus