Monday, March 14, 2011

In Good Hands

It is estimated that approximately 10% of the world’s population is left-handed. And yet roughly half of my boyfriends, half of U.S. presidents over the last century, and half of the Beatles (Paul and Ringo) were/are left-handed.* Clearly, there’s something impressive about the ability to write with one’s left hand. I’ve been fascinated with left-handedness for as long as I can remember and not just because it’s a novelty to ordinary right-handers like myself. Here’s a fun fact – while most right-handed individuals process language in the left hemisphere of their brain, a sizable proportion of lefties process language equally in both hemispheres. What would cause such a difference? And why can’t I do that? Someday I hope to address such curiosities in greater detail, but today I want to discuss a recent study not about handedness prevalence or neurological organization, but rather about the causes of positive and negative association with right and left amongst individuals with different handedness.

In many cultures, right is associated with good qualities and left with evil (or at least uncouth) traits. The English word for left is derived from a Latin word also meaning “sinister”. The French word for left is the similarly unflattering “gauche”. In some theatrical traditions, good characters enter from the right while villains slink in from the left. But these patterns may just result from the broader influence of a right-handed majority. Various studies have shown preferences in both right and left-handers for the direction that matches their own dominant hand. All other things being equal, when offered a choice between two things (two paths in a forking road, two unfamiliar products, etc) right-handers generally pick the option on the right while left-handers go for the one on the left.

The current study, to be published in a forthcoming issue of Psychological Science, hypothesized that these varied preferences stemmed not from genetic differences that accounted for handedness itself, but instead resulted the actual experience of being able to move more easily with the dominant side. To test this they examined the effects of “induced handedness” (in this case, right-handed subjects being somehow made more clumsy in their genetically dominant hand) on right/left preference.

The study was divided into two parts covering two kinds of induced handedness. The first involved subjects with long-term changes in dominant hand fluency. These were individuals who had suffered strokes that weakened or paralyzed their right sides (or left sides, for the control group). During the second part, examining short-term changes, healthy subjects were rendered temporarily disabled in their right hands for a 12-minute activity that preceded their being asked to choose between right or left options. In a shining example of the creative sadism that typifies good psychological experiments, the disabling was accomplished by having the participants maneuver dominoes while wearing an unwieldy ski glove, (adding real insult to pseudo injury, a second glove was attached to dangle awkwardly from the wrist of the same hand wearing the glove).

As predicted, in those subjects with impaired right hands, both the stroke group and the glove group generally favored left side options when presented with right/left choices, a reversal of the trend seen in those with disabled left hands. 88% of right-side-impaired stroke patients now expressed preferences akin to those of natural left-handers, and the victims of right-hand gloving were five times more likely to favor left-side options than those who had the indignity foisted on their left hands.

The study was only a small one, but it’s a fun foray into the world of handedness and its peculiar effects on your brain. It’s also an handy (pun intened) reminder of how malleable one’s decisions can be, and that going with your “instincts” may just be following a pattern dictated by your environment. I’m not arguing against the existence of free will or anything that drastic. I am merely suggesting that next time you’re lost and trying to figure out if you should turn right or left, you might consider making the decision via coin flip.   

* Just to be clear, these are entirely separate statistics. I have never dated a U.S. president or a Beatle. And it goes without saying that no member of the Beatles could hold the office of U.S. president due to the requirement that this job go to a person born in the United States.

I seem to recall hearing that this technique is also employed in some films, but I couldn’t find any research confirming it. It sounds cool though, right? I mean, correct?

Please be reminded that this study examined only subjects who were naturally right-handed. And you should be grateful, as keeping track of what’s what with all this left/right business would have been doubly confusing had they also included left-handed individuals.

1 comment:

  1. The film direction bit is from Billy Wilder.

    "Gauche" means gauche in English because the left bank (like the band) of the Seine was the unfashionable side. The right bank, Rive Droit, was fashionable. Its unlikely there was any premeditated dexterphilia amongst the hoi polloi when buying real estate.