The belief that there is a link between talent and left-handedness has a long history. Leonardo da Vinci was left-handed. So were Mark Twain, Mozart, Marie Curie, Nicola Tesla and Aristotle. It’s no different today – business leader Bill Gates is a left-hander, as is footballer Lionel Messi.
But is it really true that left-handers are more likely to be geniuses? Let’s take a look at the latest evidence – including our new study on handedness and mathematical ability.
Unsurprisingly, the role played by handedness in mathematics has long been a matter of interest. More than 30 years ago, a seminal study claimed left-handedness to be a predictor of mathematical precociousness. The study found that the rate of left-handedness among students talented in mathematics was much greater than among the general population.
However, the idea that left-handedness is a predictor of superior intellectual ability has been challenged recently. Several scholars have claimed that left-handedness is not related to any advantage in cognitive skills, and may even exert detrimental effects on general cognitive function and, hence, academic achievement.
For example, one study discovered that left-handed children slightly under-performed in a series of developmental measures. Also, a recent review reported that left-handers appear to be slightly over-represented among people with intellectual disabilities. Another large study found that left-handers performed more poorly in mathematical ability in a sample of children aged five to 14.
Left-handers seem to have, on average, an edge when solving demanding mathematical tasks – at least during primary school and high school. Also, being strongly right-handed may represent a disadvantage for mathematics. Taken together, these findings show that handedness, as an indicator of connectivity between brain hemispheres, does influence cognition to some extent.
That said, handedness is just an indirect expression of brain function. For example, only a third of the people with a more developed right hemisphere are left-handed. So plenty of right-handed people will have a similar brain structure as left-handers. Consequently, we need to be cautious in interpreting people’s hand preference – whether we see it as a sign of genius or a marker for cognitive impairment.