OFF-ROAD DRIVING EVALUATIONS FOR PERSONS WITH CEREBRAL INJURY - A FACTOR-ANALYTIC STUDY OF PREDRIVER AND SIMULATOR TESTING

Objectives. Off-road evaluations composed of psychometric testing and simulator driving are commonly used in rehabilitation settings to asse ss a person's fitness to resume driving after a cerebral injury. Altho ugh the results of these evaluation methods separately provide informa tion about ability to drive, there is no clear understanding about wha t is measured in comprehensive off-road evaluations as a whole. This s tudy explored the interrelationship of perceptual, cognitive, behavior al, and operational variables that form the basis for off-road evaluat ions in order to determine whether there are basic dimensions underlyi ng performance in these evaluations and to derive a small set of varia bles that could help in refining methods for evaluating persons with c erebral injuries. Methods. One-hundred six persons with cerebral damag e due to brain injury or cerebrovascular accident were administered a predriver evaluation that consisted of selected neuropsychometric test s. Subjects were also evaluated in a driving simulator that measured t heir operational responses to filmed driving situations and assessed t heir behaviors. Principal component analysis was used to identify mani fest and latent variables contributing to the results of the evaluatio ns. Results. The analysis produced a model with five independent (orth ogonal) eigenvectors, or factors, for this population: Higher Order Vi suospatial Abilities, Basic Visual Recognition and Responding, Anticip atory Braking, Defensive Steering, and Behavioral Manifestations of Co mplex Attention. These factors accounted for 66.14% of the total varia nce in the subjects' responses to comprehensive off-road evaluations. Conclusion. The factors were useful in understanding driving performan ce and the role of predriver and simulator testing in driver evaluatio ns.