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SUMMARY RECOMMENDATIONS 29
compensate for ambient dysfunction, the pursuit system is activated to preserve gaze stability (Leibowitz and
Post, in press). Such illusory motion is difficult if not impossible to distinguish from true object or self-motion.
RECOMMENDATIONS
The working group recommends that research be conducted on how to integrate tests of ambient vision with
tests of focal vision. For example, the contrast sensitivity function represents a significant improvement in the
evaluation of focal vision. Some tests of ambient vision are available, but they are not as well developed.
Although there exist excellent techniques for assessing vestibular sensitivity, the integrated function of the
components of the ambient system has not been extensively investigated. Quantitative evaluation of body sway
has shown considerable promise in clinical diagnosis and represents a potentially powerful methodology for
assessing task performance (Dichgans and Brandt, 1978). Individual differences in illusory self-motion (vection)
and induced tilt are marked, but their origin and significance are unknown. Sensitive measures of optokinetic
nystagmus are in extensive clinical use, but the visual parameters have not been studied in detail. Questions such
as the relative contribution of various areas of the visual field and the role of spatial frequency, contour extent,
and contrast remain to be answered. In many respects, then, the ambient system and in particular its visual
component represents an uncharted frontier with important implications for psychophysics, medicine, and human
engineering. In evaluating the role of vision in adjustment, tests of focal function are indispensable but
incomplete. Tests of spatial orientation are wanted and wanting.
SUMMARY RECOMMENDATIONS
In the body of this report the working group has discussed the value or potential value of four emerging
techniques of assessing visual function: (1) contrast sensitivity function; (2) dark-focus of accommodation; (3)
dynamic visual acuity and depth tracking; and (4) the distinction between ambient and focal modes of visual
function. The detailed recommendations made at the end of each section are often for further research.
In this section the working group offers summary recommendations based on the content of the previous
sections. These recommendations are designed to meet some immediate needs about improving the assessment
of vision and to provide a knowledge base that, 5 or 10 years from now, will be extremely valuable in the
use the print version of this publication as the authoritative version for attribution.
application of the emerging techniques to practical problems. Their ultimate goal is to provide a large data base
of basic measures and to provide further insight into the relationship between these measures and performance of
real-world visual tasks. In order for the data to be useful to a wide variety of investigators, they must be collected
with a reasonably uniform degree of reliability and
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SUMMARY RECOMMENDATIONS 30
must be free of the confounding effects of response bias. Therefore, we recommend:
(1) That a large scale program of measurement and evaluation of the contrast sensitivity function and
the dark-focus on personnel entering pilot training be initiated. Both the dark-focus and the contrast
sensitivity function should be measured using psychophysical methods that control response bias
and give a known level of statistical reliability. Personnel performing high-stress or visually critical
tasks should be periodically reexamined.
(2) That selected personnel be studied in greater depth to determine the relationship between
performance on specified visual or visual-motor tasks and their contrast sensitivity function, dark-
focus, and dynamic visual acuity. An example of such an area of study is pilots and pilot
performance during training and during operational duty. No personnel selection based on either the
dark-focus or the contrast sensitivity function should be made at this point. The large quantities of
information collected would yield solid normative data that could be used in the future for selection,
should this phase of the study show any systematic relationship between the basic measures and
performance.
(3) That these data be stored in a computer-based data access system and be made available to the vision
research community for further study. The data on contrast sensitivity, dark-focus, and dynamic
visual acuity could be used to explore many interesting issues, such as possible progressive changes
in vision during a pilot's career. A large data base would provide prevalence data on variability and
prevalence of different types of contrast sensitivity functions and dark-focus variability. The data
base would also serve as large-scale screening for the early detection of visual pathology.
(4) That an advisory panel be formed to make specific recommendations concerning the implementation
of this research program. This panel should be composed of vision researchers in the relevent fields
with the appropriate expertise.
Such an undertaking will be an exciting challenge. Although many decisions not covered by this report will
have to be made, the potential benefits are enormous. A rational basis for personnel selection based on visual
tests may be developed, avoiding the waste associated with training individuals for tasks that they will not be
able to perform. Normative standards will emerge against which an individual can be compared; the prevalence
of various types of functions will be known. A deeper understanding of vision and its relationship to task
performance will emerge.
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