- 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.
The Biggest 'Distracted-Driving' Dangers
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