What causes highway hypnosis?

Have you ever gotten home and not remembered driving there? Have you suddenly “come to” behind the wheel of a car without remembering the last few miles? You’re in a dangerous situation, but you’re not alone. What you're experiencing is highway hypnosis.

Psychologists noticed the phenomenon all the way back in 1921, when a paper about “road hypnotism” was published, about how people traveling along roads that dwindled to a far horizon point tended to enter a “trance-like state.” In 1929, a paper entitled “Sleeping with the Eyes Open” theorized that people in monotonous situations often tended to enter a sleep-like state without closing their eyes. One major example given was long, boring drives. Both papers speculated on the idea that many of the unexplained motor vehicle accidents that occurred might be due to this mysterious trance.

What causes highway hypnosis?

What causes this? Most psychologists point to a number of factors, generally grouped into the monotony of the task, the fatigue and boredom of the driver, and the ease of the driving experience. Say what you want about city drivers that honk and swear, they’re not bored. Fatigue is a major factor, since highway hypnosis approaches sleep – which is why most agencies urge people to refrain from driving if they’re overtired. One major theory, though, puts it down to the scenery that many people get when driving. An early study linked highway hypnosis to a long road and bright fixation point that draws the eye. A later study, done in 1978, indicated that monotony of scenery can eventually cause the eyes to switch to that unseeing stare that we observe on people who have tuned out.

Even if a person is staring at a fixed point, their eyes generally make little movements. Usually those movements are in response to outside stimuli – attentive movements. It’s possible that, during highway hypnosis, the eyes move to a basic predetermined pattern – intentive movements. They glance around and, if the scenery hasn't changed to a point that "wakes them," they don’t alert the brain. A long, unchanging drive might put someone slowly into this state.

But there are ways to train oneself to guard against highway hypnosis. One teenager found himself slipping so completely into an unconscious state that he’d fall asleep at the wheel even when he was fully rested and driving only short distances. Some people might solve that problem by taking away his keys and tattooing “Mass Transit Rider” on his forehead, but instead doctors attempted to re-train him. First he was trained on how to relax deeply. Once he was relaxed, he was to picture driving. After a brief driving scene, he was to picture exciting scenes that required him to be alert and involved. Eight weeks of treatment, two times a week for a half hour, he was able to drive for two hours without a problem. After three months, he could drive across the state. We’d like to think that they put some kind of warning on his car – “Driver May Be Unconscious” – but if everyone else had highway hypnosis, they wouldn’t see it, anyway.

Image: Peretz Partensky

Via Science Direct and Traffic and Transport Psychology.