Even hands-free mobile phones are dangerous for drivers

Don't - seriously, don't - ask your lover over the mobile what they're wearing while you're driving, even if you're hands-free.

The latest study on drivers' use of mobile phones concludes talking on a hands-free phone while driving is just as hazardous as holding the phone in your hands. And the most dangerous kind of conversation is one which sparks your visual imagination. Participants in the study who were distracted by visual imagery reacted half as fast to hazards as those who were not distracted.

It needn't even be something as exciting as a vision of your beloved in lycra. Simply imagining the facial expression of the person you're talking to is enough, said senior psychology lecturer Dr Graham Hole of the University of Sussex, because "the visual imagery competes for processing resources with what the driver sees in front of them on the road."

The experiment required 20 males and 40 females to sit in a car seat behind a steering wheel with pedals representing a brake and an accelerator. They were shown seven minute videos simulating road driving in which they had to respond to unexpected hazards by hitting the brake. One group was not distracted, the other group was distracted by a male voice on a loudspeaker making statements they had to identify as true or false. 

All the distracted drivers had slower response times than those who weren't distracted, but those whose answers required visual thinking - for example, "a ten pound note is bigger than a five pound note, true or false" - had the worst responses. Sentences such as "Leap years have 366 days" were less distracting.