Table 2.

Relationship of cognitive and physical measures to safe driving performance.

Test name/description	Cognitive processes and physical functions measured	Relationship to driving	Scoring
Cognitive measures
DSB  A set of increasingly longer number spans are presented and the participant is asked to repeat the number spans in reverse order.	Working memory	Retaining and manipulating information including awareness of traffic situations and the ability to recall positions of other vehicles	Number of digits repeated in correct order; longer correct spans indicate better working memory
DSF  The participant is verbally given a set of non-sequential numbers of increasing length and asked to repeat them in the presented sequence.	Immediate serial recall	Remembering driving directions, addresses, and obeying traffic warnings	Number of digits repeated in correct order; longer correct spans indicate better immediate serial recall
DST  Visual test using 6 typical driving scenes from the perspective of being behind the wheel of an automobile. After viewing a target picture a similar picture was displayed and the participant identifies differences (such as missing or added items) between the 2 pictures.	Visual scanning, visual attention, attention to detail, selective attention, working memory	Correlated with on-road driving performance; face validity and acceptability	1 point given for each detail identified; scores range from 0 (worst) to 70 (best) for all 6 driving scenes; higher scores indicate better visual attention
Maze navigationa  Tracing a route from start to finish on 2 mazes of increasing difficulty.	Judgment, planning, visual attention, forethought, simple recall	Route planning, judgment, attention	Completion time and errors; faster times to completion indicate better executive function
Three-word recalla  Three words orally presented; participant repeats the 3 words. After several minutes of intervening activities participant is asked to recall as many of the 3 words as possible.	Memory	Remembering addresses, driving instructions, and upcoming road hazard warnings	More words recalled (such as three-out-of-three) indicate better delayed recall
UFOV (subtest 2)a  The participant is presented a central object to identify and must also identify the location of an additional target object briefly presented in the peripheral field.	Visual speed of processing, divided attention	Visual attention to activity in the central field of view while simultaneously monitoring activity in the peripheral fields	Response times and error rates; faster times indicate better speed of processing and divided attention
VMI (computerized version of the Motor-free Visual Perception Test/Visual Closure subtest)a  The participant is asked to match 11 partially completed line drawings to a complete target object.	Information processing, inference, outcome prediction, visual perceptual ability	Spatial integration; identification of objects when partially visualized	Number of correct responses; more correct responses indicate better information processing, inference, outcome prediction, and visual-perceptual ability
VSA (computerized TMT–A)a  Screen with scattered numbers (1–25).	Information processing speed, visual search, attention	Scanning, searching, and monitoring the driving environment; maintaining attention	Completion time, accuracy; shorter times and better accuracy indicate better visual search and information processing
VSB (computerized TMT–B)a  Screen with scattered letters and numbers (1-A, 2-B, 3-C, etc.)	Information processing speed, visual search, attention, attention switching	Scanning, searching, and monitoring the driving environment; maintaining attention to sequencing mental flexibility	Completion time, accuracy; shorter times and better accuracy indicate better visual search and sequencing, information processing, and attention switching
Physical measures
RFTT  The participant taps their right foot alternately 5 times on each side of a 2-inch 3-ring binder as quickly as possible for a total of 10 taps.	Lower extremity control, flexibility, and proprioception	Moving between the brake and gas pedal	Completion time; shorter times indicate better right lower extremity control, flexibility, and proprioception
Rapid Walk Testa  The participant walks as quickly and safely as possible for 10 feet around a cone or other marker, and returns to their starting place (total distance walked is 20 feet).	Lower extremity strength and mobility	General lower extremity strength and mobility; moving the leg and foot between the brake and gas pedals, and entering and exiting the vehicle	Completion time; shorter times indicate better general mobility and lower extremity strength
Head and neck flexibilitya  The participant is seated in a chair and must look over their shoulder without moving their hips and identify a shape on the computer screen 10 feet directly behind them.	Head and neck flexibility, range of motion	Visualizing traffic, pedestrians, and other objects when changing lanes, at intersections, or when backing up	Pass or fail indicating head and neck flexibility and range of motion
High and low contrast visual acuity and contrast sensitivitya  The participant is presented with a series of progressively smaller and less contrasted “E” symbols and must detect the E with a different orientation than the others.	Visual acuity, contrast sensitivity	Read traffic signs, see road markings, and navigate safely in low-light situation such as dusk, fog, or rain	Fewer errors indicate better visual acuity and contrast sensitivity

Note: All measures are valid and reliable for use in the study population.

Abbreviations: DSB = digit span backward; DSF = digit span forward; DST = Driving Scenes Test; RFTT = Right Foot Tapping Test; TMT–A = Trail Making Test A; TMT–B = Trail Making Test B; UFOV = Useful Field of View Test; VMI = Visualizing Missing Information; VSA = visual search–A; VSB = visual search–B.

^aComponent of the DrivingHealth Inventory.