Driver behaviour and training edition:4 location:Amsterdam date:24-25 November 2009
Multiple Sclerosis (MS) is a chronic illness of the central nervous system causing different symptoms that affect important skills in the driving task. The condition is progressive, so that there is a point in time in which the patient is no longer capable of safe driving.
The purpose of the study was to assess whether persons with MS can evaluate their own driving skills accurately.
20 persons with MS (mean age 49 ±9) and 17 healthy controls (mean age 41 ±16) from 22 to 62 years old took part in the experiment. The male-female ratio (40%-60%) was equal in both groups. All participants drive a normal car with a gear shift (without adjustments) regularly.
The results of a subjective measure of driving skills (questionnaire) were compared to an objective measure (driving simulator test). The driving test consisted of three separate trajectories assessing skills that may be affected by visual, cognitive and physical limitations. The questionnaire contained the same items.
Results of the questionnaire indicate that persons with MS acknowledge that they have problems while driving, which are caused by MS, but they do not think these have a significant effect on their driving abilities. They rate their own abilities even higher than the healthy control group does on questions such as “how much difficulty do you have with overtaking?”. In contrast, their self-evaluation is relatively pessimistic in questions about divided attention. The simulator driving test revealed that persons with MS perform worse than healthy controls, especially on a secondary task and when having to overtake other vehicles.
When subjective and objective measures of driving skills are compared, persons with MS overestimate themselves more than the healthy control group. The overestimation is significant but does not necessarily indicate a problem of unsafety in traffic. The overestimations are more prominent when judging traffic flow, operationalized by overtaking manoeuvres, and to a lesser extent concerning divided attention. The group is more accurate in assessing their physical abilities, but their performances are also the best in this domain.