Using smartphones for social networking while driving is more dangerous than drink driving or being high on cannabis behind the wheel, according to research published today by the IAM (Institute of Advanced Motorists).

Despite this, 8% of drivers admit to using smartphones for email and social networking while driving - equivalent to 3.5 million licence holders, while the problem is greater with younger drivers with 24% of 17-24 year olds - a group already at higher risk of being in a crash - admitting to using smartphones for email and social networking while driving.

For their research, the IAM and TRL (Transport Research Laboratory) used DigiCar - TRL's car driving simulator - to examine the effects of young drivers using smartphones to access Facebook. In every test of driving performance, young people who were using Facebook while driving were badly affected.

When sending and receiving Facebook messages: reaction times slowed by around 38% and participants often missed key events; participants were unable to maintain a central lane position resulting in an increased number of unintentional lane departures; and were unable to respond as quickly to the car in front gradually changing speed.

When comparing these new results to previous studies the level of impairment on driving is greater than the effects of drinking, cannabis and texting.

• Using a smartphone for social networking slows reaction times by 37.6%

• texting slows reaction times by 37.4%

• hands-free mobile phone conversation slows reaction times by 26.5%

• cannabis slows reaction times by 21%

• alcohol (above UK driving limit but below 100mg per 100ml of blood) slows reaction time by between 6 and 15%

• alcohol at the legal limit slows reaction times by 12.5%

The IAM is calling for government action to highlight the dangers of using smartphones behind the wheel. Phone manufacturers and social network providers also have a key role to play in spreading the message. Attitudes to seatbelts and drink driving have changed dramatically over the last thirty years, and, with the right information, halting smartphone use could become a similar success story.

IAM chief executive Simon Best said: "This research shows how incredibly dangerous using smartphones while driving is, yet unbelievably it is a relatively common practice. If you're taking your hand off the wheel to use the phone, reading the phone display and thinking about your messages, then you're simply not concentrating on driving. It's antisocial networking and it's more dangerous than drink driving and it must become just as socially unacceptable.

"Young people have grown up with smartphones and using them is part of everyday life. But more work needs to be done by the government and social network providers to show young people that they are risking their lives and the lives of others if they use their smartphones while driving."

TRL senior researcher Nick Reed said: "Our research clearly demonstrates that driver behaviour was significantly and dramatically impaired when a smartphone was being used for social networking. Drivers spent more time looking at their phone than the road ahead when trying to send messages, rendering the driver blind to emerging hazards and the developing traffic situation.

"Even when hazards were detected, the driver's ability to respond was slowed. The combination of observed impairments to driving will cause a substantial increase in the risk of a collision that may affect not only the driver but also their passengers and other road users. Smartphones are incredibly useful and convenient tools when used appropriately and responsibly. Their use for social networking when driving is neither."