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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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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.
Representative terms from entire chapter:
electronic travel
