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SUMMARY AND HIGHLIGHTS In this report we identify the most promising directions for research on the mobility problems of visually impaired and blind people. We show that information is not generally available on the number of people who might benefit from electronic travel aids. Although we have made some guesses about the prevalence of visual impairment and blindness in the United States, we believe them to be underestimates of the true rates. Better information is needed about this population and should be collected with certain variables in mind: age, onset, degree of impairment, and certain social factors such as income level. Information is also not available on the use of electronic travel aids. More extensive follow-up studies are needed to determine the usefulness and success of particular devices. Related to the use of electronic travel aids is the problem of the assessment of mobility performance in general. In this report we show that significant advances have been made in the development of objective measures of overt performance. These measures have not received wide- spread distribution, however, in part due to inadequate documentation of the techniques and the requirement for specialized measurement equipment to apply them. Accordingly, we believe that greater emphasis should be placed on the development and dissemination of promising assessment measures--objective and subjective, direct and indirect--and that emphasis should be given to these assessment methods in training programs for mobility specialists. Mobility is undertaken with a purpose in mind, that of reaching a destination. We have attempted to outline the nature of the perceptual processes and the cognitive knowledge base available to the blind pedestrian. In the absence of a sufficient theory of mobility, however, the theoretical underpinnings of blind mobility depend on the research traditions in perception and cognition. Unfortunatelv. r~s~r~h wi th blind individuals has received far too investigators although there are 50mR little attention by experienced _ _ ~- ~ notable exceptions. Research is needed on how much information is required by the blind traveler, the use of natural cue correspondence, the role of information redundancy, orientation in space, and the nature of the perceptual-motor learning processes that underlie the use of mobility aids. There is an urgent need to determine how--and to what extent-- sensory substitution or enhancement techniques can best be used to 1

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2 compensate for deficiencies in the acquisition of spatial motor behaviors in people with visual impairments. The visual system is capable of resolving information in both the immediate and remote environments, but this is not always true for auditory or somatosensory modalities. More emphasis is needed, therefore, on research exploring the possibility of coding spatial distance through a sonar system with some complex form of acoustical amplitude, and on the design and development of an artificial device to simulate tactile perception. With respect to the enhancement of low vision, common measurement metrics expressed in visual terms need to be developed to evaluate vision substitution systems. The first generation of mobility aids (e.g., the Russell Path- sounder, the Laser Cane, the Mowat Sensor) was criticized on grounds that included cost-effectiveness and the masking of natural echo and location cues. In the late 1970s and early 1980s, developers came up with some new solutions to address these problems. Nonetheless, existing devices still have limitations. We believe that further improvements in electronic mobility aids will be limited less by technological considerations than by the determination and definition of the information needed by the traveler and the capacity of the nonvisual senses to process the information via a suitably encoded display. This report attempts to direct future research so that we will learn more about visually impaired or blind travelers--how many there are, the prevalence of various impairments, how to assess their performance, what information they need about space to move about safely and efficiently, and what displays are likely to meet their information needs. Compared with these issues, the development of appropriate technology is relatively straightforward. Highlighted below are some of the most important points we make, cross-referenced to the appropriate recommendations in the report: Independent travel is an important goal sought by most visually impaired and blind people. While the long cane has significantly improved their mobility, many hope that advances in electronics technology will yield an electronic travel aid (ETA) that provides the same type of information about space as that which guides the travel of sighted pedestrians. To date, no ETA has been built that permits travel performance similar to that of sighted pedestrians or that enables independent and safe travel by visually impaired or blind pedestrians in unfamiliar surroundings. A better under- standing of the factors underlying the mobility process is needed if effective ETAs are to be designed, developed, and used. Information is generally unavailable about the size, characteris- tics, and needs for mobility of the population to be served by electronic travel aids. Surveys are needed to provide better information about users of this technology and about the factors that contribute to the nonuse of ETAS. (See pp. 23-24, 76) Better and more consistent information should be collected on mobility performance. Objective measures are usually not used

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3 outside the laboratories in which they were developed. Widespread use of improved measures of mobility would facilitate the comparison and/or replication of research on the problems of visually impaired and blind people; such information would also improve training strategies and enhance the use of ETAs. (See pp. 33, 74) It is generally accepted that, in order to engage in safe and efficient travel, pedestrians must have access to certain categories of information about the environment: the presence, location, and nature of obstacles; the texture, slope, and boundaries of the path or travel surface; and the spatial orientation. People vary widely--whether sighted, partially sighted, or blind--with respect to their selection and use of information about their surroundings when moving from one place to another. Advances in mobility research will depend on identification of the or it ; ~~ 1 i norms ; an used by the traveler. (See pp. ~ _ _ _ _ _% ~ _ ~ &= ~^ Ill~ ~ ~ v ~ ~ 49-52/ 75) Different methods of displaying information needed for mobility should be carefully designed to match the sensory system and should be tested by experimentation. It is possible to simulate informa- tion displays, manually or with simple technology, to test their effects on mobility performance. Yet simulation methods are often overlooked as an approach to the study of mobility performance. (See pp. 33-34, 50-51, 65, 75, 78-80) . Further improvements in electronic travel aids will be limited less by technology than by knowledge of the information needed by the traveler and the capacity of the nonvisual senses to process that information in suitably coded displays. Research is needed on how to match auditory, tactual--and, when appropriate, visual-- information displays to sensory processes so that information about the environment can be selected and used by the blind or visually impaired traveler. {See pp. 51, 62-64, 77-78) To implement the working group's recommendations, it will be necessary to enhance cross-disciplinary research on the mobility problems of blind and visually impaired people. Incentives must be provided at the national level to attract the most able researchers from a broad spectrum of fields to apply their skills to the problems of mobility outlined in this report.