The Beckman Institute driving simulator has been home to many studies of driver distraction, but Human Perception and Performance group member Dan Simons has used it to take a fresh look at the topic.

Simons, a Professor of Psychology at Illinois, ran an experiment in the simulator that tested driver distraction during real-world driving situations such as changing lanes or passing in traffic with cars traveling at variable speeds. The results were reported in a paper by Simons and lead author William Horrey that appeared recently in a special issue of the journal Ergonomics dedicated to driver safety.

"What made our study different is that we were looking at how people compensate for distraction under more naturalistic driving conditions, Simons said. "Other people have looked at compensation effects, but they havent directly compared compensation for distraction under steady-state performance and tactical control situations."

Simons said their study contrasted steady-state car following (following another car going at a constant speed), one of the standard tasks in driver distraction studies, with tactical control driving (making decisions, such as whether to speed up in order to pass), which is closer to what drivers typically find in the real world.

Past research has shown that performing another task while driving (such as talking on a cell phone) leads to slower responses and greater risk of accidents. To compensate for these impairments, drivers in steady-state driving conditions adaptively increase their safety margins such as the distance between their vehicle and the one they are following.

Simons and Horrey found the same pattern for steady-state driving, but they also discovered that drivers in tactical control conditions do not in fact compensate for the extra mental workload by increasing their safety margins in dual task situations. Simons said he wasnt surprised by the findings.

"Tactical driving demands much more attention from the driver, and interference is that much more detrimental," Simons said. "More importantly, when people are engaged in tactical driving, they are less attuned to the distraction of the dual tasks, so they do not adjust their driving safety margins sufficiently.

"More broadly, drivers often do not realize the effect that distraction has on their driving performance. To paraphrase Ellen Goodman from a column she wrote for the Boston Globe, 'everybody else when they are driving and talking on a cell phone is an idiot, but Im fine.'"

Simons said that people might not realize the extent to which distraction affects their ability to respond to unexpected events while driving. Consequently, they do not compensate for those impairments.

For more on the paper, click here.