Consumers are increasingly using MP3 players in their vehicles, and auto makers have responded: Data show that 90% of new vehicles sold in the United States have MP3 connectivity. Makers of aftermarket MP3 controllers are also responding with devices that have claimed to decrease driver distraction. But according to human factors/ergonomics researcher John D. Lee and colleagues, MP3 players might increase distraction risk, depending on which devices drivers use and how long they look away from the road while searching for their favorite song. Aftermarket devices designed to reduce distraction can actually increase it. In a new article published in Human Factors: The Journal of the Human Factors and Ergonomics Society, 50 drivers age 18 to 25 searched for specific songs in playlists of varying lengths using either an MP3 player or an aftermarket controller. They performed this task in a driving simulator while negotiating varying road segments with frequent changes in traffic patterns and construction activity. In comparison trials they were asked to tune the radio to a particular frequency while driving.

Lee and colleagues found that drivers who searched through long playlists (580 songs) glanced away from the road more frequently and for longer durations than did those scrolling through shorter playlists, resulting in degraded driving performance. The aftermarket controller was found to lengthen, not shorten, glances away from the road. "As seen in this study, these aftermarket devices do not always have the expected effect," Lee noted.

These results are significant because they bring yet another dimension to the driver distraction challenge. The most recent figures from the U.S. Department of Transportation indicate that, despite the numerous education campaigns and laws aimed at mitigating driver distraction, the problem may actually be getting worse.

"New technology in the car often seems like familiar old technology, such as a radio, but is often much more likely to distract," said Lee. "A simple task of selecting a song from a list can seduce（引诱） you into looking away from the road longer than you might have intended, and long looks away from the road can kill."