People whose minds wander intensely while driving are significantly more likely to be responsible for a crash and are threatening safety on the roads, researchers warn.
The term "mind wandering" has been coined to describe thinking unrelated to the task at hand. It happens most often at rest or during repetitive tasks.
All drivers experience occasional drifting of their minds towards internal thoughts, a temporary "zoning out" that might dangerously distract them from the road.
External distractions (such as from mobile phones) are known to be linked with crashes, but inattention arising from internal distractions (such as worries) is still poorly understood in the context of road safety.
A team of researchers from France therefore wanted to see if mind wandering would increase the risk of being responsible for a crash.
They interviewed 955 drivers injured in a motor vehicle crash attending the emergency department at Bordeaux University Hospital between April 2010 and August 2011. All participants were 18 years or older.
Patients were asked to describe their thought content just before the crash. Researchers also assessed how disruptive/distracting the thought was.
Mitigating factors considered to reduce driver responsibility, such as road environment, traffic conditions, traffic rule obedience and difficulty of the driving task were also taken into account.
Finally, blood alcohol level was tested as well as the driver's emotional state just before the crash.
They classified 453 (47 per cent) drivers as responsible or the crash and 502 (53 per cent) as not responsible.
Over half (52 per cent) reported some mind wandering just before the crash, and its content was highly disrupting/ distracting (defined as intense mind wandering) in 121 (13 per cent).
Intense mind wandering was associated with greater responsibility for a crash - 17 per cent (78 of 453 crashes in which the driver was thought to be responsible) compared with 9 per cent (43 of 502 crashes in which the driver was not thought to be responsible).
The authors concluded in a statement that the association between intense mind wandering and crashing "could stem from a risky decoupling of attention from online perception, making the driver prone to overlook hazards and to make more errors
The study was published in British Medical Journal.