The Left Hand Man

Left-handers make great baseball pitchers, but they’re generally considered lousy subjects for studies of the brain. “Every good neuroscientist knows you don’t test lefties,” explains Daniel Casasanto, assistant professor in psychology. “They mess up your data.”

Perhaps it’s justice. After years of being relegated to uncomfortable right-handed desks (to say nothing of scissors or spiral notebooks) lefties exact their revenge in MRIs. Among righties, brain lateralization—the control of functions and behaviors by particular brain hemispheres—is fairly consistent. Among lefties, however, it’s messier and much less predictable, complicating results.

But rather than avoiding southpaws, Casasanto has devoted years to studying them, hoping to learn how and why their brains diverge from those of right-handers. It’s part of a larger effort to understand the relationship between our bodies and our minds. Does experiencing the world in different bodies cause us to develop correspondingly different brains? Casasanto thinks so.