How Do Task Structure and Uncertainty Influence Task-Interleaving Strategies During Distracted Driving?

During distracted driving, people commonly alternate or interleave attention between driving and another task. One factor that influences task interleaving is task structure. Specifically, people tend to switch between tasks at sub-tasks boundaries. Uncertainty about the roadway environment during glances away from the road, however, may play a larger role in shaping task interleaving strategies during distracted driving. The purpose of this study was to examine task interleaving strategies when drivers completed a distracting task of various subtask sizes. Participants entered phone numbers, modified zip codes, or digit strings while performing a lane-keeping task. In general, the time between button presses in the secondary task was significantly greater between sub-tasks than within sub-tasks. However, as sub-tasks became larger drivers switched more frequently within sub-tasks than between sub-tasks. Additionally, participants’ did not change their visual sampling strategies as the size of sub-tasks increased. Thus, uncertainty influenced decisions to switch between two interleaved tasks in the driving environment more than sub-task boundaries.