University of Utah researchers used a series of driving-simulation tests to determine that hands-free gadgets such as a Bluetooth headset are just as distracting as holding a phone to your ear. Talking on a cell phone slowed the reaction times of adult drivers aged 18 to 49 to those of senior citizens, according to the study published in the Journal of Experimental Psychology.

Passengers, even chatty ones, are far less distracting because they can point out hazards or remind drivers of upcoming exits, and are more likely to change a conversation (by shutting up or talking less) when driving conditions change -- and because they're in the car, they're more likely to notice that the driver needs to focus.

Two videos from the study show the dangers of driving while phone-chatting. In one, drivers using a hands-free device to talk on the phone inadvertently pass a highway exit that they had been instructed to take. In another, the drivers aren’t on the phone, but rather are chatting with a passenger. These drivers successfully take the rest-area exit because their passengers alert them to do so.

This research reinforces earlier reports that just because you're chatting hands-free doesn't mean your driving won't suffer -- although several states have enacted such laws.

The study calls into question the safety of hands-free devices, and the benefit of state laws that require drivers to use them. Personally, I’m less aware of the road while chatting on my Bluetooth headset. So what’s the answer? If safety’s the ultimate goal, perhaps we should simply ban mobile phone use while driving. No, I’m not thrilled with that solution either, but until self-driving cars become a reality, it may be necessary.