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Focus on Driving: How Cognitive Constraints Shape
the Adaptation of Strategy when Dialing while Driving
Duncan P. Brumby, Dario D. Salvucci, Andrew Howes
Link to CHI 2009 paper.
Overview:
As mobile devices become more common, more distracted drivers take to the roads. Over the years, studies have concluded that interacting with other people or devices while driving increases the risk of being involved in an accident. This results from the driver's need to perform multiple tasks at once--diverting their attention off of the road. These tasks must be interleaved together in order to accomplish them. This paper focuses on identifying the different methods people use to interleave concurrent tasks.
Experiment:
The experiment was conducted using a driving simulator. Subjects drove a vehicle down the center lane of the highway which was lined with construction cones on either side. The vehicle moved at a constant speed so the subjects only had to focus on keeping the vehicle in the center lane and dialing numbers on a cell phone. Key presses on the phone were recorded and timestamped.
In the first part of the experiment, participants were timed on how fast and accurately they could dial the number. Then, they interacted with the simulator, trying to keep the vehicle centered in the lane while traveling at a constant speed. In the second part of the experiment, subjects interleaved the tasks based on different priorities: dialing focus or steering focus.
Results:
The data shows that when the subjects used their phones, their performance was impaired because their attention was focused on things other than driving. Improvements in lane keeping only occurred during long delays between key presses, and the vehicle moved further away from the lane center during shorter key press intervals. The duration of time between key presses can be used to determine when drivers were focusing their attention on the driving task.They also saw that participants use hierarchical chunks to determine when they were to switch from one task to another (ex: xxx-xxx-xxxx). The experiment shows that they would break the dialing up into these chunks and lane keeping would improve during the period of time between these chunks.
From here, they tried to determine which strategy of task interleaving would be most efficient in terms of driver performance. For this, they used a Cognitive Constraint Modeling (CCM) framework to explore alternate task interleaving strategies. They were able to derive performance predictions for each strategy that was implemented.They found that drivers who didn't return their attention to the driving task at least twice experienced large lane deviation. Those who made a correction to steering after dialing the first chunk experienced less lane deviation while dialing the second chunk. Though it might have not been needed the first time, it decreased the amount of lane deviation they experienced in the future.
Conclusion:
Their findings support the idea that the total time a driver is distracted from their primary task is less important than the extent to which they glance back at the road while trying to complete the secondary task. Designing mobile devices that don't require long periods of interaction could be helpful in reducing the "deleterious effects of distraction."
