TP 13889E
February 2002
Joanne L. Harbluk
Y. Ian Noy
Ergonomics Division
Road Safety and Motor Vehicle Regulation
Transport Canada
and
Moshe Eizenman
EL-MAR Inc.
Abstract
Driver distraction and inattention are important driving safety issues.
As the use of in-vehicle technologies becomes more popular, there is concern
about a concomitant increase in driver distraction arising from their use.
While the introduction of hands-free operation for telematics devices is
intended to reduce or eliminate the distraction due to manual operation
of these units, a significant proportion of the distraction associated with
their use may arise not from the manual manipulation of these devices, but
rather the cognitive consequences of their use.
In the present study, the impact of cognitive distraction on drivers'
behavior was investigated in an on-road experiment. Twenty-one drivers
drove an 8 km city route while carrying out tasks varying in cognitive
complexity. Each driver drove the route under three task conditions: while
performing difficult addition problems (e.g., 47+38), while performing easy
addition problems (e.g., 6+9), and with no additional task. The addition
questions and the participants' responses were communicated via a
fully hands-free cell phone so that the participants did not have to
look away from the road to manually operate the phone. Visual scanning
patterns were recorded using eye tracking equipment, measures of vehicle
control (braking/longitudinal deceleration) were obtained using the
MicroDAS system, and drivers' subjective evaluations of workload (NASA
TLX), safety and distraction were obtained through questionnaires.
An examination of drivers' visual behavior revealed that, under
conditions of increased cognitive load, they made fewer saccades, spent
more time looking centrally and spent less time looking to the right
periphery. Less time was spent checking instruments and the rear view
mirror. Many drivers changed their inspection patterns of the forward view
when performing the most demanding tasks. Marked individual differences were
observed in these patterns of change. Performing the additional tasks while
driving resulted in more incidents of hard braking while driving. The
increase in cognitive load induced by the addition questions was reflected
in drivers' increased ratings of workload and distraction as well as reduced
ratings of driving safety.
The results of this study indicate that even when in-vehicle devices
are hands-free, significant changes in driver behaviour may result due
to the cognitive distraction associated with their use. A better understanding
of the ways in which drivers interact with these devices should result in
improved designs that minimize the amount of distraction.
The study recommends public education, as well as continuing research
to determine the need for regulating original equipment.
You may download the full
report The Impact of Cognitive Distraction on Driver Visual
Behaviour and Vehicle Control, in Portable Document Format (PDF) (162Kb).
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