I once knew a professor who was famous for his animated teaching- he would scribble on the board with both hands at once, unable to contain his excitement for the topic. This professor was also the president of our university, and an absolute genius. He only required 3 hours of sleep each night (self-proclaimed on his facebook page), and was bouncing with energy and initiative every morning. While he wasn’t sleeping, it was easy to imagine his brain firing like a lightening storm on speed.
I was thinking about this professor while studying for my psychiatry rotation today, and wondered whether smarter people tend to be left handed or ambidextrous. Left-handed people are incredibly over represented in our med school class- while about 9 out of 10 people are right handed in the general population, I’d have to say only about 7 out 10 people are right handed in our class (myself included). It would make sense that lefties are smarter- they’re more likely to involve not only their left hemisphere for language, but also their right. This would surely force them to create more neuronal connections, no?
So, on a whim, I decided to try and use only my left hand for writing during my entire six week psych rotation. Then I promptly abandoned my studying to scribble all over the back of my notes:
You may be a lot less than impressed at my messy left handed scrawl, but before you judge, consider this: my right handed note-taking masterpiece.
Pretty similar, eh? I was so excited at the idea of becoming ambidextrous that I hopped on to my lappy and started to blog, wanting to encourage you all to try it out for a week. But my scientific conscience got the better of me (thankfully), and I slowed down to do a literature search before babbling about improving your left-hand dexterity.
The results are quite fascinating. A proportion of children (a little over 10%) develop left-handedness in every culture and ethnicity. Rates of adult handedness vary depending on the cultures’ emphasis on hand conformity. In Canada for example, the rate of left-handedness is 12.8%, compared to only 2.5% in Mexico (Perelle 2004).
Interestingly, left-handedness is seen more frequently in patients with schizophrenia, in children born pre-maturely, and in those who may have suffered a brain insult (hypoxia, menigitis) (Vuoksimma 2009). The proportion of left-handers among the cognitively impaired is also higher than in the general population.
Mixed-handedness (having dextrous use of both left and right hand) is associated with early onset dementia, and more severe atrophy of the hippocampus and amygdala (both parts of your brain involved in memory and emotion) (Cherbuin 2011).
But its not that straightforward or that depressing. Lefties are also over-represented among the extremely gifted population. Moreover, 20% of Mensa High IQ society members are left-handed, which is double the statistical norm (Vuoksimma 2009)!
Mixed-handers tend to have a thicker corpus callosum (the neuronal tissue that connects the two sides of your brain) and have been consistently shown to perform better on certain types of memory tests than their one-handed counterparts (Christman 2011).
So after all of that, I’m as conflicted about the topic as ever! I want so badly to put “ambidexterity” on my resume, but I’m a little frightened of the threat of early onset dementia. Of course, I haven’t mentioned or even looked into effect sizes, so the increased risk of losing my mind early could be tinier than a molecule’s ass =)
What do you guys think? Have you had any experiences learning to write with your other hand?