The Science Of Being A Southpaw

by Matt Sitman

Maria Konnikova reviews shifts in the scientific understanding of left-handed people:

In 1977, the psychologist Theodore Blau argued that left-handed children were over-represented among the academically and behaviorally challenged, and were more vulnerable to mental diseases like schizophrenia. “Sinister children,” he called them. The psychologist Stanley Coren, throughout the eighties and nineties, presented evidence that the left-handed lived shorter, more impoverished lives, and that they were more likely to experience delays in mental and physical maturity, among other signs of “neurological insult or physical malfunctioning.” Toward the end of his career, the Harvard University neurologist Norman Geschwind implicated left-handedness in a range of problematic conditions, including migraines, diseases of the immune system, and learning disorders. He attributed the phenomenon, and the related susceptibilities, to higher levels of testosterone in utero, which, he argued, slowed down the development of the brain’s left hemisphere (the one responsible for the right side of the body).

But over the past two decades, the data that seemed compelling have largely been discredited. In 1993, the psychologist Marian Annett, who has spent half a century researching “handedness,” as it is known, challenged the basic foundation of Coren’s findings. The data, she argued, were fundamentally flawed: it wasn’t the case that left-handers led shorter lives. Rather, the older you were, the more likely it was that you had been forced to use your right hand as a young child. The mental-health data have also withered: a 2010 analysis of close to fifteen hundred individuals that included schizophrenic patients and their non-affected siblings found that being left-handed neither increased the risk of developing schizophrenia nor predicted any other cognitive or neural disadvantage. And when a group of neurologists scanned the brains of four hundred and sixty-five adults, they found no effect of handedness on either grey or white matter volume or concentration, either globally or regionally.

She goes on to note research that found numerous cognitive benefits associated with being left-handed, including studies that connect it to greater creativity.