How much do you notice while you're on your cellphone? Not as much as you may think

Forget about the elephant in the room. Let's talk about the clown on the unicycle.

Just how much do you notice going on around you when talking on a cellphone? Not as much as you might think, according to a new study to be published in the December issue of Applied Cognitive Psychology.

In examining "inattentional blindness" or failing to see what's there because a person is distracted, Ira Hyman, a psychology professor at Western Washington University, looked at the effects of divided attention during walking.

Prof. Hyman and his team observed more than 100 people as they walked through the campus, some talking on cellphones or listening to MP3 players, others walking without any electronics or walking in a pair. The entire group walked past a clown riding a unicycle planted by Prof. Hyman's team and were asked afterward if they had noticed the strange sight.

Of those listening to MP3 players or walking without any devices, more than 50 per cent noticed the clown; 70 per cent of those walking in pairs saw the clown, while only 25 per cent of people on phones noticed.

"[Cellphone users] just are substantially less likely to notice things," Prof. Hyman says, adding that the study is proof that cellphones are dangerous in the hands of drivers.

"Walking is just about the easiest way of navigating you've got. If a clown hits you with a cream pie it's not the end of the world," he says.

"But when you're talking about driving and failing to notice unusual stimuli or new stimuli, you're going to miss another car, you're going to miss a pedestrian, you're going to not see that cyclist out there."