Daydreaming: The Other Kind of Distracted Driving

For many, the term “distracted driving” conjures up a familiar image: a motorist talking or texting on a cell phone instead of paying attention to the surrounding traffic and road conditions. The dangers of phoning or texting while driving are so evident that 13 American states have passed laws banning use of handheld devices while driving.

But can distracted driving also be caused by internal factors? Psychological scientists Matthew R. Yanko and Thomas M. Spalek of Simon Fraser University in British Columbia wanted to gauge whether simple “mind-wandering,” thinking about anything but the task at hand, would distract drivers the same way portable gadgets do. Yanko and Spalek conducted two experiments designed to test whether mind-wandering affected critical aspects of driving such as reaction time (for braking), velocity, and headway distance (space between cars).

During the first experiment, Yanko and Spalek had 17 drivers follow a car that set the pace for them and braked randomly throughout the 30-minute session. In addition, a series of auditory prompts asked the driver to indicate — by pressing one of two buttons — whether, at that moment in time, they had been focused on the task at hand or whether their mind had been wandering.

Results suggested participants were distracted, or concentrated on something other than driving, approximately 39% of the session. In addition, the vehicle velocity, and the time it took motorists to start braking when the car in front of them slowed down, both increased when drivers rated their minds as wandering. During this experiment, headway distance was controlled by the pace car, and so did not vary regardless of the drivers’ states of mind.

During their second experiment, the researchers examined in a separate set of 32 drivers whether mindless driving could affect headway distance. The lead vehicle was programmed to maintain a specific speed, while the drivers were allowed to vary their speed. In addition, Yanko and Spalek introduced another factor — a woman walking toward the road — into this experimental condition to test whether this set of distracted drivers would react more slowly to a peripheral event occurring on their left or right, just as the drivers in the first experiment did to a vehicle braking in front of them.

Yanko and Spalek found that drivers’ minds wandered approximately 42% of the session’s duration. During those mind-wandering periods, drivers followed the lead car, which was traveling at a fixed speed, more closely than when they were concentrating on driving. Furthermore, the reaction times for both tasks (braking for the lead car and for the woman stepping onto the road) increased when the drivers were distracted or thinking of something else.

The researchers’ work, detailed in Human Factors: The Journal of the Human Factors and Ergonomics, provides some of the first concrete evidence that mind-wandering affects time-sensitive aspects of driving, such as how long it takes distracted motorists to brake or whether they will speed up if they are not paying attention to the task at hand. Yanko and Spalek point out that other research has linked such behavior to increased likelihood of crashing, making it doubly important for drivers to keep their minds focused on the road ahead.