Mobile phone use drastically reduces our ability to pay attention to things going on around us.

So claims researchers at Western Washington University who have studied the ability of around 300 individuals to notice a unicycling clown in a busy square on the university campus.

Of those using a mobile phone, just 25 per cent noticed the clown, while those walking alone, in pairs, or listening to music noticed the clown more than 50 per cent of the time.

Even worse, the study showed that mobile phone use even affects our ability to walk properly. Those talking on their phones tended to walk slower, change direction and weave more often and acknowledge other individuals more rarely.

Dr Ira E Hyman Jr, head researcher of the study, said the results of the survey proved the sense of restricting mobile phone use while driving.

"If people experience so much difficulty performing the task of walking when on a [mobile] phone, just think of what this means when put into the context of driving safety," he noted.

The results of the study are to be published in an upcoming issue of Applied Cognitive Psychology.