Vision, Aging and Road Safety
By D. Alfred Owens, PhD
Compared
to previous generations, today's older adults are healthier, more
active and more likely to hold a driver's license. But aging takes a
toll, and accident rates begin to climb after retirement. By age 80,
fatality rates (per miles driven) approach those for teenagers (Evans,
1991). While some of the increased fatalities among older adults can be
attributed to fragility, another part of the problem is behavioral.
Age-related impairments of vision, cognition and action can interfere
with abilities to recognize and react quickly to hazards.
The
most-frequently-discussed approach to this problem is to retest older
adults for license renewal. Although this approach seems reasonable,
the standard vision tests are unable to predict which individuals are
at risk of a mishap. Indeed, recent evidence suggests that strict
screening of older drivers is counterproductive. A comparison of
Finland's rigorous re-licensing of older adults versus Sweden's
laissez-faire system found no evidence for greater safety through
re-licensing (Hakamies-Blomqvist, et al., 1996).
Recent Research
A
scientific solution to the problems of aging drivers awaits development
of valid licensing criteria, which will require a fuller understanding
of the behavioral and cognitive processes involved in driving. Recent
research is beginning to fill the gap. One promising development is the
Useful Field of View (UFOV) test, which assesses the span and speed of
visual attention by measuring one's ability to recognize targets that
are flashed briefly in the near periphery, within about 15 degrees of
fixation. The UFOV tests skills that are probably used in routine
maneuvers like lane changes and turns across traffic.
Another important development comes from research on visual guidance of locomotion, which depends on ambient vision. Recent studies have found that, for young drivers, control of steering and speed remains highly efficient, even when central vision is degraded by low luminance or blur (Higgins, Wood & Tait, 1998). In contrast, the steering ability of older drivers decreases dramatically in low light. This suggests that, along with age-related impairments of central vision, full-field ambient vision also diminishes with age. Many seniors compensate for these changes by avoiding risky situations, but developing of a practical test of ambient vision is a high priority.
In the Meantime ...
How can we address the
difficulties of older drivers until more valid, practical tests become
available? Beyond conventional vision and health exams, which can
reveal some serious impairments, two behavioral measures seem
worthwhile (Platt, 1996).
First, a road test that includes traffic situations of graduated complexity can be diagnostic of behavioral or cognitive problems. The test should begin in a familiar locale with sparse traffic, then move on to less familiar, busier situations. A "commentary" test, in which the driver reports aloud every event and action, is also quite revealing; it is difficult, and it helps the driver to recognize his/her limitations.
Older adults should also plan ahead for the likelihood of restricted driving. It is relatively easy for us to acknowledge that sometime in the future we must limit, or give up, driving. With this in mind, each individual can agree in writing that family or friends will inform him/her when problems become evident. According to this agreement, the individual will then consult with a trusted health advisor and, if the problems are confirmed, he or she will be prepared to curtail or cease driving.
D. Alfred Owens, PhD, is Professor of Psychology, Franklin and Marshall College in Lancaster, PA.
References:
Evans, L. (1991). Traffic Safety and the Driver. New York: Von Nostrand Reinhold.
Hakamies-Blomqvist,
L., Johansson, K., & Lundberg, C. (1996). Medical screening of
older drivers as a traffic safety measure -- A comparative
Finnish-Swedish evaluation study. Journal of the American Geriatric
Society, 44 (June), 650-653.
Higgins, K., Wood, J., & Tait, A.
(1998). Vision and driving: Selective effect of optical blur on
different driving tasks. Human Factors, 41 (2), 224-232.
Platt, F.N. (1996). Going on 80 II. Tune Up Your Driving Skills. Kennett Square, PA: Fletcher N. Platt, AlphaGraphics
Source: Lighthouse International's Aging & Vision newsletter (Summer-Fall 2001)
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