Banner -- Identifying Strategies to Collect Drug Usage and Driving Functioning Among Older Drivers
 

ON-ROAD TESTING

Naturalistic Studies (Driving In Traffic) continued...

This research deserves attention due to its careful design, seeking measures for a comprehensive range of behaviors that could be meaningful in gauging the safety of older drivers. Unfortunately, some of those measures with the highest construct validity in explaining maneuver errors at intersections, where older drivers are at greatest risk, did not yield usable data in this investigation. Their application in future studies may also be questioned, accordingly.

Specific strengths of the measurement methods employed by Roenker et al. (2003) included:

  • repeating the route to allow the subject to become more comfortable with the evaluation process and to make it more likely that the driver would revert to everyday driving behavior;
  • use of scales including four levels rather than a simple pass/fail judgment to allow for finer gradations in the observation of on-road driving behaviors;
  • use of two raters to evaluate driving behaviors, rather than one evaluator, plus checking for (and confirming) high inter-rater reliabilities, bolstering claims that driving behavior was judged objectively;
  • use of a fuller range of driving behaviors than assessed in prior research, grouped into composites which in turn were made up of numerous samples of driving behavior rather than a single instance; and
  • evaluations were conducted across all daylight hours (7 a.m. to 5 p.m.) to encompass a wide range of driving conditions.

Next, an on-road standardized driving test was developed in research performed by Richardson and Marottoli (2003) to determine which driving behaviors and situations are related to cognitive risk factors such as visual attention and spatial abilities in older people. Thirty-five community-dwelling active drivers 72 and older underwent the driving evaluation, as well as tests of visual attention, executive function, visuospatial cognition, and memory. The cognitive measures included the logical memory (verbal memory) and visual reproduction (visual memory) of the Wechsler Memory Scale-Revised, the Hooper Visual Organization Test (visuospatial cognition), the number cancellation task (visual attention), the Trail-Making Test Part B (executive function), the Symbol-Digit Modalities test, and experimental measures of simple, choice, and complex reaction times. The driving test was taken from the 36-item relicensing exam used by the Connecticut Department of Motor Vehicles for individuals referred for examination because of medical reasons. The only change made to the exam was in the scoring procedure. Instead of coding items as “pass” or “fail,” items were coded on a 3-point system, as follows: major errors/unsafe (0 points); minor errors (1 point); and good/no errors (2 points). The maximum number of points attainable was 72. The 36-item scale used to evaluate driving skills for a separate set of 357 older drivers showed high internal consistency when used by two evaluators.

The road test employed by Richardson and Marottoli (2003) began with parking lot maneuvers, and progressed to suburban roads in urban downtown traffic, and to driving on limited-access highways. The road course was 20 miles long and required 45 to 60 minutes to complete. A driving therapist riding in the passenger seat of a dual-brake equipped vehicle evaluated each participant’s driving skills. Road test scores ranged from 14 to 72. Visual attention was associated with 25 of 36 driving items, highlighted with an asterisk in the list below, and included scanning the environment, interacting with other road users, and monitoring speed and judging distances appropriately. Visual memory was associated with 16 maneuvers, and executive function was related to 17 maneuvers. Most of these maneuvers overlapped with visual attention.

  • Scan to sides*
  • Scan to rear/head check
  • Uses mirrors
  • Uses safety belt
  • Responds to traffic signals*
  • Responds to vehicles/pedestrians*
  • Grants right-of-way*
  • Centers car in lane*
  • Safe following distance*
  • Uses directional signals*
  • Positions car for turns*
  • Proper lane selection*
  • Gas-to-brake reaction time*
  • Appropriate steering recovery*
  • Acceleration
  • Braking*
  • Shifting
  • Right turns
  • Left turns*
  • Backing up
  • K turns
  • Angle parking
  • Low-density traffic*
  • Simple traffic situations*
  • Medium traffic situations*
  • Limited access highway*
  • Enter
  • Exit*
  • Merge*
  • Lane change*
  • Speed regulation*
  • Follows directions*
  • Judgment*
  • Decision-making*
  • Memory
  • Attitudes and emotions*
 

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