A University of Utah volunteer drives through Salt Lake City's Avenues neighborhood as a camera tracks her eye and head movement. Another device records driver reaction time, and a cap fitted with sensors charts brain activity. AAA Foundation for Traffic Safety hide caption

toggle caption AAA Foundation for Traffic Safety

A woman uses a cellphone while driving in Los Angeles in 2011. Damian Dovarganes/AP hide caption

toggle caption Damian Dovarganes/AP