Are Lefties More of a Danger on the Road?

"I think probably left-handers have more accidents because it's a right-handed world. That probably accounts for most of it," Howard Kushner, a historian of medicine and neuroscience, and the author of "On the Other Hand: Left Hand, Right Brain, Mental Disorder, and History," says.

Maybe the closest we'll get to a real answer on lefties and driving comes from a study by psychologist Stanley Coren, the author of the 1993 book, "The Left-Hander Syndrome: The Causes and Consequences of Left-Handedness." Coren points to a reflex action that may work against left-handed drivers, at least in places where cars operate on the right-hand side of the road (which, of course, is most of the world).

In his study, Coren threw foam rubber balls at people, most of whom reflectively tried to block the ball with their nondominant hand. That'd be bad news if it happened on the interstate at rush hour.

From Coren in the August 1992 issue of the American Journal of Public Health:

Cornell psychologist Daniel Casasanto sees that as a completely plausible explanation because of something called "approach and avoidance" actions, which have been physically traced in a kind of emotional map of the brain. The "approach" emotions (things like happiness) were long thought to be gathered in the right side of the brain. The avoidance (disgust, fear) were in the left.

But a few years ago, scientists found that those emotions were completely flipped in the brains of left-handers. The approach emotions — you might call that the "good" side — were on the left. The bad (the avoidance emotions) were on the right.

To the left-handed brain, left is good. Right is bad.

"The way we conceptualize emotions depends on the way we use our hands to interact with the world. That's not a theory that anybody had suggested before a few years ago," Casasanto says. "We know it's true because this, 'Right is good, left is bad' that is found across languages and across cultures is also found in the unconscious, in the right-handers' minds. But the exact opposite is found in left-handers' minds, in spite of everything that language and culture is telling us."

Back to the road: If a lefty driver sees something bad on the road ahead, Casasanto suggests, that triggers an avoidance mechanism in the brain. For the lefty, the right hand rises to avoid, either pushing the wheel initially to the left (counter-clockwise) or allowing, even briefly, more pull from the dominant, left-hand (again, counter-clockwise). That, if true, could spell trouble on the road.

(If it seems strange that you'd avoid something or try to block something with your nondominant hand, Casasanto suggests thinking more in a "sword and shield" kind of way. The sword is in your dominant hand. The shield is in the other one.)

Short of going all Mad Max to test these things out in a real-world setting, all this remains hypothesis. But it's an intriguing one. If a little scary for lefties.

We can, at times, ascribe way too much importance to handedness. Like eye color or the color of skin, which way you throw a ball doesn't, in the end, make you more or less human.

"Differences, different traits like handedness, eye color, other things that make people look different from one another," says historian Kushner, "... we shouldn't overly burden them with having some kind of deeper meaning than they actually do."

Still, there is some meaning there. Finding out why some people go left and others right, why and how different people think what they do, matters. It's why scientists have been looking at it for centuries.

"It matters because the way we interact with our environment is a huge part of how we learn," Casasanto says. "And our hands are a really important point of interface between the person and the world."