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OCR for page 29
About this PDF file: This new digital representation of the original work has been recomposed from XML files created from the original paper book, not from the original typesetting files. Page breaks are true to the original; line lengths, word breaks, heading styles, and other typesetting-specific formatting, however, cannot be retained, and some typographic errors may have been accidentally inserted. Please 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

OCR for page 29
About this PDF file: This new digital representation of the original work has been recomposed from XML files created from the original paper book, not from the original typesetting files. Page breaks are true to the original; line lengths, word breaks, heading styles, and other typesetting-specific formatting, however, cannot be retained, and some typographic errors may have been accidentally inserted. Please 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. use the print version of this publication as the authoritative version for attribution.