Sensory aids for the blind: A challenging problem with lessons for the future

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Abstract
The two major objectives of sensory aids for the blind are to permit access to printed matter and to permit safe travel through the environment. The difficulties of designing technological means to achieve these objectives are in many respects unrelated to the concerns of the engineering laboratory. Social, economic, political, and logistic considerations all play a role. The "blind population" in the United States includes both the totally blind and those with a wide range of visual impairment. This population totals about 400 000 people in which the aged, the multiply handicapped, and those with significant residual vision predominate. Singly handicapped, working-aged people are the initial targets of the current sensory aids. Expansion of their range of usefulness to larger fractions of the blind population is expected to come later. About 800 agencies serve the blind population in the United States, and in 1967 they were responsible for an annual expenditure of $500 million. In contrast the sensory-aids research and development budget was less than $1 million. Nevertheless, several potentially useful prototype devices have been developed and are about to be evaluated in this country; at least one is of foreign origin. But if these devices are ever to have the opportunity of reaching the blind public, then mechanisms for evaluation, field trials, manufacture, and deployment must be set up. The field of currently active sensory-aids research programs is reviewed. Several programs are concerned with increasing the convenience and accessibility of braille by the application of computer technology. Nevertheless, despite the unquestionable value of these developments, the usefulness of braille is limited by its bulk, its cost, and the transcription time. To provide direct access to printed documents several devices are being developed that transform optical images from a printed page into auditory or tactile displays requiring motivation and training for effective use. These machines are termed "direct-translation" units and are designed for simplicity and low cost. Other systems utilize print recognition techniques to create a reading machine providing braille or speech as an output. These machines offer potentially faster reading rates and their use promises to be easier to learn than direct-translation machines, but at the penalty of complexity and high cost. Several mobility aids designed to augment the cane or guide dog have recently been developed. These are also described. The prospects of achieving direct input to the visual cortex are discussed. It is apparent that the cost of this research is likely to be extremely high in relation to the size of the blind population which might ultimately benefit. Somewhat more easily realizable is a visual substitution system involving stimulation of an area of the skin. Several systems are being developed but all suffer from limitations in image resolution. Finally, an examination of the organization of research and funding reveals that the U.S. program is small, poorly coordinated, and contains some seemingly unnecessary duplication of effort. Several obvious lessons emerge which, if heeded, could greatly improve the effectiveness of sensory-aids research by providing development, manufacture, evaluation, and deployment services within an integrated program.

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