Abstract:
A wealth of research has identi ed how distractions impair driving performance and
compromise safety. Research has shown that drivers can strategically adapt their interac-
tions with distractions to mitigate decrements in driving performance, but the strategies
that drivers use to achieve these outcomes are still unknown. When people engage in an-
other visually demanding task while driving, they have to strategically alternate attention
between driving and the distracting task to achieve performance objectives. This is known
as task interleaving. Several studies have suggested that people switch between tasks at
sub-task boundaries to minimize the cognitive cost associated with suspending and resum-
ing a task. The driving environment, however, cannot be neglected for long without serious
safety consequences and some sub-task boundaries may be unattainable. Uncertainty about
the roadway environment increases when the driver is not attending to the roadway, and
research has shown that growing uncertainty over time dictates how drivers look to and
from the roadway.
Only two studies have examined task interleaving strategies in the driving environment,
but the in
uence of sub-task boundaries and time on participants' task interleaving strate-
gies in these studies was confounded. The current research expanded upon previous work
by systematically varying sub-task size and driving demand to tease apart the role that sub-
task boundaries and elapsed time play in people's task interleaving strategies in the driving
environment. Experiments 1 and 2 showed that drivers interleaved at sub-task boundaries
less often when sub-tasks in a distractor task were larger. Additionally, Experiments 1 and
2 showed that the time people looked away from the roadway did not change signi cantly
as sub-task size increased. Experiment 2 and 3 showed that task performance was more
e cient when sub-tasks in the distractor task were chunked in memory. Experiment 3
showed that increasing lane width increased the time drivers were willing to neglect the
driving task. While drivers still primarily switched between tasks as a function of time
in Experiment 3, sub-task boundaries did in
uence task interleaving strategies when the
sub-tasks of the distractor task were chunked in memory and participants had more time to
look away from the roadway. Overall, task interleaving strategies were primarily in
uenced
by time, but drivers seemed to be opportunistic and switched at sub-task boundaries when
the time required to complete a sub-task aligned with the time constraints of the driving
environment.
