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ELECTRONIC TRAVEL AIDS: NEW DIRECTIONS FOR RESEARCH Working Group on Mobility Aids for the Visually Impaired and Blind Committee on Vision National Research Council National Academy Press Washington, Die. 1986

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NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance. This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The National Research Council was established by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy's purposes of furthering knowledge and of advising the federal government. The Council operates in accordance with general policies determined by the Academy under the authority of its congressional charter of 1863, which establishes the Academy as a private, nonprofit, self-governing membership corporation. The Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in the conduct of their services to the government, the public, and the scientific and engineering communities. It is administered jointly by both Academies and the Institute of Medicine. The National Academy of Engineering and the Institute of Medicine were established in 1964 and 1970, respectively, under the charter of the National Academy of Sciences. Available from: Committee on Vision National Research Council 2101 Const itution Avenue Washington, D.C. 20418 Printed in the United States of America

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WORKING GROUP ON MOBILITY AIDS FOR THE VISUALLY IMPAIRED AND BLIND EMERSON FOULKE (Chair), Perceptual Alternatives Laboratory, University of Louisville (low vision) PAUL BACH-Y-RITA, Clinical sciences Center, University of Wisconsin (physiology) BRUCE B. BLASCH, Waisman Center, University of Wisconsin (blind rehabilitation) JOHN BRABYN, Smith-Kettlewell Eye Research Foundation, San Francisco (rehabilitation engineering research) JAY ENOCH, School of Optometry, University of California, Berkeley (optometry, low vision) ELEANOR E. FAYE, New York Lighthouse for the Blind (ophthalmology, low vision) GREGORY GOODRICH, Veterans Administration Medical Center, Palo Alto, California (low vision) ARTHUR H. KEENEY, Department of Ophthalmology, University of Louisville (ophthalmology, ocular injuries) LAWRENCE SCADDEN, Electronics Industry Foundation, Washington, D. C. (low vision) DAVID H. WARREN, Department of Psychology, University of California, Riverside (psychology) ~

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COMMITTEE ON VISION ANTHONY J. ADAMS (Chair), School of Optometry, University of California, Berkeley ROBERT SEKULER (Past Chair), Departments of Psychology, Ophthalmology, and Neurobiology/Physiology, Northwestern University IRVING BIEDERMAN, Department of Psychology, State University of New York, Buffalo RANDOLPH BLAKE, Cresap Neuroscience Laboratory, Northwestern University RONALD E. CARR, New York University Medical Center SHELDON EBENHOLTZ, Department of Psychology, University of Wisconsin ANN B. FULTON, Department of Ophthalmology, Children's Hospital, Boston CHRIS A. JOHNSON, Department of Ophthalmology, University of California, Davis JO ANN KINNEY, Surry, Maine AZRIEL ROSENFELD, Center for Automation Research, University of Maryland PAMELA EBERT FLATTAU, Study Director 1V

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FOREWORD The Committee on Vision is a standing committee of the National Research Council's Commission on Behavioral and Social Sciences and Education. The committee provides analysis and advice on scientific issues and applied problems involving vision. It also attempts to stimulate the further development of visual science and to provide a forum in which basic and applied scientists, engineers, and clinicians can interact. Working groups of the committee study questions that may involve engineering and equipment, physiological and physical optics, neurophysiology, psychophysics, perception, environmental effects on vision, and treatment of visual disorders. To perform its role effectively, the committee draws on experts from a wide range of scientific, engineering, and clinical disciplines. The members of the working group responsible for this report were chosen for their expertise in vision research and for their familiarity - w~th past efforts by government and private agencies to harness advanced technology to serve blind and visually impaired persons. The report reflects their evaluation of the usefulness and durability of uresent- day mobility aids given the tasks confronting bland or visually impaired pedestrians. The report provides an account of the mobility task and of the r)ercentual . mini ~ ive, And maker f''n - it; rung:: ''navel vi no The _ . . . . . . _ , ~ ~ _ _ _ _ = ~ , _ _ ~ _ _ performance of that task. The report describes the people who might profit from using effective mobility aids and some of the techniques currently being used to judge the effectiveness of available aids. The report reviews information regarding the sensory systems available to blind and visually impaired pedestrians and the possibilities for the . ~ . . _ . . . . . . . . . . . . application or new technologies to the mobility task given those sensory processes. The observations and recommendations arising from the efforts of the working group merit consideration by mobility specialists whether they are involved in the assessment and training of the blind and visually impaired, the design of the mobility aids to serve the needs of that population, or the support and conduct of basic research in this area. - v Anthony J. Adams, Chair Committee on Vision

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CONTENTS PREFACE SUMMARY AND HIGHLIGHTS 1: INTRODUCTION The Problem of Mobility for Blind and Visually Impaired Pedestrians, 5 The Mobility Task, 5 Abilities and Skills, 6 Establishing Performance Criteria, 7 Component Skill Criteria, 8 Guide to the Report, 8 2: THE DEMOGRAPHY OF BLIND AND VISUALLY IMPAIRED PEDESTRIANS Some Definitions, 10 Demographic Characteristics, 11 Age, 13 Onset of Visual Problems, 15 Degree of Visual Impairment, 17 Additional Impairments, 18 Social Factors, 19 Approaches to Aiding Mobility, 20 Patterns of Use and Nonuse, 21 Recommendations, 23 Surveys of ETA Users and Technology Diffusion, 23 A Normative Data Base, 24 A Survey of the Needs of Older Blind People, 24 Review and Analysis of Existing Data Bases, 24 Study of Multiple Impairments, 25 Development of a Research Agenda, 25 3: THE ASSESSMENT OF MOBILITY Individual Characteristics, 26 Psychosocial Characteristics, 27 Sensory and Motor Characteristics, 27 Perceptual and Cognitive Characteristics, 28 vii xi 1 4 10 26

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Measures of Mobility Performance, 28 Indirect Measures, 28 Direct Measures, 29 Outcome Measures of Successful Mobility, 30 Assessment of Mobility, 31 Assessment of Mobility Aids, 31 A Standardized Method for Assessing Travel Performance, 31 Recommendations, 33 Standardized Measures of Mobility Performance, 33 Simulation Methods, 33 Improved Field Assessment Techniques, 34 Technology Benchmarks, 34 Training Programs, 35 4: PERCEPTUAL , COGNITIVE , AND ENVIRONMENTAL FACTORS The Mobility Task, 36 Perceptual, Cognitive, and Motor Functions, 36 Perceptual Information, 37 Cognitive Information, 39 Perceptual-Motor Skills, 42 Mobility Skills, 43 Applications of General Knowledge, 43 Applications of Specific Knowledge, 44 Individual Differences, 45 Risk Estimation and Risk Taking, 46 Early Versus Late Blindness, 46 Overprotection, 47 Neurological Damage, 47 Remaining Vision, 48 Conclusion, 48 Recommendations, 48 Making Information Available to the Blind Traveler, 49 Forms of Information Display, 50 The Relationship Between Perceptual and Cognitive Information, 51 Perceptual Learning Principles, 51 SENSORY ENHANCEMENT AND SUBSTITUTION The Visual System, 54 The Immediate Environment, 54 Remote Environments, 54 Sensory Enhancement, 56 The Auditory System, 56 The Somatosensory System, 5 7 Pressure, 58 Vibration, 58 Tactile Form Perception, 58 Texture, 59 Stereognosis, 59 Implications for Sensory Aids, 59 36 53

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Existing Environmental Sensors, 60 Sonar Substitution, 60 Tactile Substitution, 61 Recommendations, 62 The Somatosensory System, 62 The Auditory System, 63 Mobility and Low Vision, 64 Detrimental Effects of Mobility Aids, 65 Animal Models, 65 6 THE TECHNOLOGY OF ELECTRONIC TRAVEL AIDS Information Needs of the Pedestrian, 67 Past and Present Mobility Aids, 68 The Long Cane, 68 Electronic Travel Aids, 68 Clear-Path Indicators Versus Environmental Sensors, 69 Recent Developments, 70 Limitations of Existing Technology, 7 3 Recommendations, 74 Problem Definition, 75 Technology for Display Design and Simulation, 75 Technology for Optical Aids, 76 Technology for Information Acquisition, 7 6 Technologies for Information Display, 78 Technology for Information Processing, 80 REFERENCES GLOSSARY WORKSHOP PARTICIPANTS SELECTED BIBLIOGRAPHY 1X 67 81 91 93 95

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PREFACE r At the request of the National Institute of Handicapped Research and the National Science Foundation, the Committee on Vision established the Working Group on Mobility Aids for the Visually Impaired and Blind. The working group was asked to summarize current understanding of the basic dimensions of mobility, to comment on the status of devices that have been designed and built to assist the visually impaired people and to determine a research agenda that would strengthen the knowledge base underlying the design and use of mobility aids. To accomplish these goals, the working group organized a workshop to review what is known about the design and use of mobility aids by visually impaired and blind people. Twenty-eight specialists in the fields of demography, performance assessment and training, psychology, geography, sociology, ergonomics, engineering, and physiology met for two days in Washington, D.C., in November 1985. Workshop participants were asked to consider the current state of mobility research and to suggest what further research would improve the design and use of mobility aids. Panels were formed and asked to address five major questions: Panel 1: Who are the people who might benefit from travel aids? What dimensions might be used to classify them--along an age continuum, by kind of visual impairment, by degree of impairment? How well have people been able to use travel aids in the past? Why do some dis- continue their use? In what ways are travel aids used differently in different environments? Panel 2: Which travel aids have worked, which have not? Which which have not? How can training and performance of visually impaired and blind people be assessed--by stride length, for example, or by focusing on whole-body movement? (The emphasis of this panel is the assessment of performance, not of electronic or other aids.) Panel 3: What do blind or visually impaired people need (or might find useful) to know about the environment? Where in space is the information to be found--e.g., in the path ahead, at the surface on which they will walk? Are the processes involved conceptual? What is their relative dependence on perceptual information or on information retrieved from memory? training methods have worked, xi

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Panel 4: What are the capacities of the different senses to acquire information about space? How may acoustical and proprioceptive stimuli be used? How should information about space be displayed? Panel 5: What kinds of aids are needed, given what we know about the kind of spatial information a person is likely to use? What are the limitations of existing devices? What are the new directions that might be taken in the development of new devices. __;__ m=: A background paper addressing the target questions was prepared for each panel and distributed well in advance of the meeting. Participants prepared a brief, informal response to their panel's background paper. Background papers and panelist responses were disseminated to all work- shop participants in advance of the meeting to facilitate workshop -~rv~=ui~. finis report builds on those papers and comments as well as on discussions that took place at the workshop. In addition to the 28 participants in the workshop, a number of people contributed in important ways to the success of the workshop and to this report of its recommendations. Wayne Shebilske, the committee's study director through June 1985, planned the workshop, and Pamela Ebert Flattau, the committee's study director after July 1985, provided important assistance in organizing the effort and in preparing the workshop report. Gora P. Lerma, the committee's administrative secretary, provided valuable secretarial and administrative assistance. Christine L. McShane, editor of the Commission on Behavioral and Social Sciences and Education, helped improve the style and clarity of the report. And finally, Estelle H. Miller of the National Academy Press lent her excellent production skills to the project in preparing the report for publication. Emerson Foulke, Chair Working Group on Mobility Aids for the Visually Impaired and Blind xii