During the tests, volunteer drivers were asked to wear a device that tracked eye movements and then asked to perform a number of tasks while driving. The data shows that rather than being attributed to the holding of a handset, the risk of in-car mobile phone use should be attributed to performing a cognitive task. When using a mobile phone, eye movement tends to be narrow – thus posing a threat on the roads.

The biggest risk to drivers occurs when thinking about things such as lists or numbers or previous conversations, rather than when performing tasks like turning the radio on – these affect the range of vision temporarily.

Researchers will continue to investigate the matter, but meanwhile are encouraging drivers to use mobiles only during good weather, good traffic conditions and on open flat roads.