A recent study of driving behaviour in the US has concluded that up to 25% of all road accidents could be caused by distracted drivers.

Rather than analyse drivers directly, the study, performed by the Governors Highway Safety Association (GHSA), looked at research from over 350 scientific papers on driver distraction in an attempt to provide a comprehensive overview of the problem.

The study identified four types of driver distraction: looking at something other than the road (visual), hearing something not related to driving (auditory), manipulating something other than the wheel (manual) and thinking abut something other than driving (cognitive).

Inevitably, most in-car distractions combine two or more of these distraction types and some of the research found that drivers were distracted for between 25% and 50% of the time they were behind the wheel of a car.

It’s important to note, however, that most distractions only last a second or two, but such things as glancing at a vehicle’s controls and chatting to a passenger while driving both count as distractions — and they can be too numerous to count on a journey.

Although much of the study might sound like common sense to anyone with more than an ounce of it, many road traffic laws are decided on a state-by-state basis in the US and there’s a wide variation in what drivers are allowed to do across the country.

Many states, for example, only consider not wearing a seatbelt to be an offence if the driver is first stopped and issued a ticket for another driving offence. Similarly, handheld mobile phone use while driving is only prohibited in nine states and even handheld text messaging is legal in some.