The new NAB Driving Scenes test appears to have good ecological validity for on-road driving abilities in older adults, including healthy elderly and individuals with very mild dementia. Our findings revealed a strong association between scores on the NAB Driving Scenes test and on-road driving test score. Moreover, those rated as “safe” by the driving instructor performed significantly better on the NAB Driving Scenes than those rated as either “marginal” or “unsafe.” The NAB Driving Scenes test was able to correctly classify 66% of the participants into these three driving safety categories.
These findings suggest that the NAB Driving Scenes test has utility in clinical evaluations of older adults whose driving abilities are in question. Difficulty on the NAB Driving Scenes test suggests that a formal driving evaluation should be recommended, particularly in combination with findings on other neuropsychological tests associated with driving abilities, such as the Trail Making Test (DeRaedt & Ponjaert-Kristoffersen, 2001
; Odenheimer et al., 1994
; Rizzo et al., 1997
). As with any neuropsychological measure, when interpreting test results or making recommendations pertaining to driving ability, alternate explanations for poor performance must be entertained (e.g., fatigue, poor motivation) as well as converging evidence from a wide range of sources, such as clinical history and significant others (Sbordone & Purisch, 1996
Another advantage of the NAB Driving Scenes test for use with older adults is its face validity for driving abilities. The stimuli are digitally-smoothed, life-like color drawings of a visual perspective from behind the steering wheel of a car driving on a two-lane road through the downtown of a small city. In addition, aspects of the pictures that change or are added are commonly encountered events while driving (e.g., stop light turns red, child runs into road, engine heat indicator increases). The face validity of the test makes it more palatable to examinees, and may also decrease the likelihood of the examinees refusing participation altogether. Patients, their families, and caregivers will likely be more open to driving-related recommendations when they are made and explained on the basis of a test (such as the NAB Driving Scenes) that clearly appears to be related to aspects of real-world driving. The NAB also includes two equivalent forms, as well as six-month test–retest data, thus making reevaluation with the Driving Scenes test possible with little or no practice effects. Finally, the NAB may also have advantages over computerized tests, such as ease and convenience of administration and acceptableness to older adult examinees.
In one review of the literature, the relationship between most neuropsychological test scores and various measures of everyday functioning was estimated to range between 0.20 and 0.50, which are low to moderate correlations (Williams, 1996
). In a recent meta-analysis of the relationship between neuropsychological test performance and on-road driving skills (Reger et al., 2004
), the mean correlations were 0.36–0.48. Laudably, the NAB Driving Scenes test’s association with driving abilities falls at the upper end or greater of those previous findings. One limitation of our findings is the small sample size in the discriminant function analysis, which may create instability in those findings. Thus, replication is warranted with a larger sample.
In summary, the NAB Driving Scenes test provides an ecologically valid measure of driving abilities. As pressure increases from clinical, legal/forensic, and research-oriented consumers/users of neuropsychological test data for ecologically-valid information, this test may be an appropriate addition to a testing battery for a variety of purposes.