Assisting the older driver - SWOV

Effects of a driver support system on workload and driving performance
tests were considered to be functionally younger, whereas persons scoring
relatively poor on them were considered to be functionally older.
The support system that was evaluated was designed to reduce workload
and improve driving performance. To measure whether timely information
about what to expect indeed reduced mental workload, a secondary task was
introduced (see e.g., Wickens & Holland, 2000 and Kantowitz & Simsek, 2001
for the merits of secondary‐task performance as an indicator of workload).
This secondary task consisted of a peripheral detection task (PDT; see e.g.,
Van Winsum, Martens & Herland, 1999). While driving the simulator car,
participants had to detect a signal that was sent to the screen. As soon as they
detected the signal, they had to press a button that was attached to the index
finger of their left hand. Performance on this secondary task was inferred
from the reaction time of the drivers. In addition, subjective workload was
measured. At the end of each drive, participants were asked to rate the
difficulty of the task they had just completed (i.e., driving the simulator car
with or without the support system installed) on a scale from 0 to 150 (Rating
Scale Mental Effort (RSME); Zijlstra & Van Doorn, 1985). Primary task
performance was inferred from crashes, route‐errors, and safety of the
participant’s decisions. The latter was measured by the extent to which traffic
that had right of way had to decelerate when the participant was passing an
intersection. Deceleration of these ‘other vehicles’ was considered to be the
precursor of a crash. If the drivers of those vehicles would not have reacted, a
crash would have taken place.
In general, we hypothesized that functionally older drivers would benefit
more from the information provided by the support system than functionally
younger drivers would. We expected that this benefit would be reflected in
experienced workload, in safety of driver decisions, and in appreciation of
the support system. More specifically, we expected that there would be an
interaction effect of age and driver support leading to a) a relatively larger
decrease in workload for functionally older participants, b) a relatively larger
increase in the safety of driver decisions of functionally older participants,
and c) a higher appreciation of the support system by older participants.
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