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Abstract
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The logical assumption has always been made that vision plays an important role in the driving task. This assumption has traditionally been accepted by driver-licensing agencies and used as the basis for incorporating one or more vision tests in procedures for evaluating driver license applicants. Such universal usage notwithstanding, however, there has been in fact no definitive experimental evidence relating visual ability to driving ability and, thus, no experimental justification for the use of vision tests for screening license applicants.
A detailed survey pointed out that few, if any, basic relationships between vision and driving have been established by previous research, largely for the following reasons:
1. Vision is only one of many factors influencing driving performance; hence, it is unlikely that a close relationship exists between any single vision characteristic and a measure of driving performance, such as number of crashes.
2. It is difficult, if not possible, to ascertain the efficiency with which an individual's visual capabilities are utilized in driving.
3. Visual characteristics evaluated in research may not correspond closely to visual functions required in driving.
4. The reliability and validity of the measure (e.g., number of crashes) used as a criterion of driving performance may be questionable.
5. The research study may have had methodological shortcomings, such as an inadequate and/or unrepresentative sample of the driving population, uncontrolled extraneous variables (e.g., mileage driven), or unreliable measures of visual performance.
Driver-licensing officials are faced with the responsibility of determining effective screening procedures of all types for driver license applicants and are keenly aware of the need for accurate information upon which to base their operational decisions. In an effort to provide such information in the area of vision, the Institute, in conjunction with the California Department of Motor Vehicles (DMV), began in 1962 a large-scale, long-range study of the relationships between visual ability, as measured on several standard and nonstandard screening tests and driving performance, as reflected in driving record. The purpose of this paper is to present major findings resulting from the first phase of this research program, which involves comparing visual performance with three-year driving records. A second phase of the study is currently underway and involves (a) retesting a number of the original subjects, after a period of two to three years, to determine whether an appreciable change in visual performance occurs over this relatively short period of time; (b) accumulating driving record information over a six-year period, to provide a more valid and reliable measure of driving performance; and (c) in-depth analysis of the massive amount of data accumulated in the study, to evaluate such things as the relationship between specific types of crashes and specific types and degrees of visual degradation. |