- Regular driving. Strayer gave driving with no distractions a baseline ranking of Category 1.
- Listening to the radio. This activity also rates a Category 1, as the professor calculated it only involves 121% of regular driving's "mental workload."
- Listening to books on tape. Strayer estimates listening to books on tape requires 175% the brainpower of regular driving, meaning it's still a Category 1.
- Hands-free cellphone calls. Hands-free cell calls rank a Category 2 because they require an estimated 227% as much mental work as basic driving does.
- Talking to a passenger. Holding a conversation with another person in your car is a Category 2 task because it involves some 233% as much cognitive effort as regular driving.
- Hand-held cellphone calls. Talking on a cellphone you hold in your hand ranks a Category 2, as it demands roughly 245% the concentration that driving with no distractions does.
- Dictating an email with speech-to-text system. This activity rates a dangerous Category 3 because it involves an estimated 306% as much brainpower as driving a car with no side activities.
- Doing math/memory problems. To learn whether mental distractions impair drivers more than physical ones (such as holding a cellphone), researchers gave test subjects a series of math and memory problems to solve while traveling down the road. While drivers would never do such work in real life, Strayer ranked the tests -- which involve brainpower but no physical effort -- a Category 5 because they require an estimated 500% of simple driving's cognitive effort.
BOSTON ( TheStreet) -- Hands-free cellphone systems distract drivers almost as much as holding a device up to your ear -- and voice-to-text email programs are more or less the worst of all, AAA research shows. "'Hands-free' is not risk free," says University of Utah researcher David Strayer, who recently studied distracted driving for AAA. "You can get impairments even with some of the new voiced-based
systems that allow you to keep your hands on the wheel and your eyes on the road." Strayer and his team performed a series of experiments on volunteers to measure how a range of distractions -- from listening to the radio to answering math questions -- affect driving proficiency. Using road tests and driving simulators, researchers monitored how volunteers' brake times and adherence to speed limits and proper following distances changed as subjects engaged in a series of side activities. Investigators also recorded participants' brain waves and eye and head movements to see how well drivers stayed focused on the road.