How being left-handed changes your perception of the world

The illustrations below are called Fribbles. They're generated by a computer, and psychologists can use them in Rorschach-like tests: How participants rate them says more about the participants than about the drawings.

So: Which one do you like better? Which one is more intelligent? More attractive? Happier?

In 2009, psychologist Daniel Casasanto published an experiment that asked those very same, very odd, questions. Usually, nonsense questions about nonsense drawings should not produce meaningful data. But they did.

Here's why: Forty of his 286 participants were left-handed. And when they looked at Fribbles arranged in a column on the left-hand side of a page, they tended to like them better than Fribbles on the right-hand side.

It's not just Fribbles. For lefties, the left side of the world is just ... better.

"Righties implicitly think right is good, lefties implicitly think left is good," Casasanto told me last year for a story in National Journal.

Casasanto had recently published an experiment that found — amazingly — that fictional political candidates got a 15 percent bump among left-handers if they were listed on the left-hand side of a ballot. (Casasanto said he wouldn't expect to see that large a difference in the real world, where many other factors, like party affiliation, come into play. But in light of data that finds that ballot order can, in fact, influence elections, he thinks it could potentially have an effect on less-informed or ambivalent voters.)

But why would hand dominance change the way we feel about the world? An answer can be found in a theory called embodied cognition. It's the idea that thoughts are simulations of actions.

Here's what I mean by that: When you close your eyes and imagine yourself throwing a baseball, the same parts of your brain are activated as when you actually throw the baseball. Benjamin Bergen, a cognitive scientist at UC San Diego, offers some more examples in his book Louder Than Words: The New Science of How the Mind Makes Meaning:

Think about the direction you turn the doorknob of your front door. You probably visually simulate what your hand would look like, but if you’re like most people, you do more than this. You are able to virtually feel what it’s like to move your hand in the appropriate way—to grasp the handle (with enough force to cause the friction required for it to move with your hand) and rotate your hand (clockwise, perhaps?) at the wrist. Or if you’re a skier, you can imagine not only what it looks like to go down a run, but also what it feels like to shift your weight back and forth as you link turns.

So if our bodies anchor our thoughts, do they, in turn, shape our thoughts? "If thinking is embodied in this sense," Casasanto hypothesized in his 2009 paper, "then people with different kinds of bodies must think differently."

If your body favors the left side of the world, your thoughts will, too.

We're mostly unaware of our hand bias

Here's another (very odd) experiment Casasanto conducted. Participants were told a story about a "good" animal and a "bad" animal, and then were asked to draw the animals.

Instructions indicated that when participants flipped the page they would meet a cartoon character who was planning a trip to the zoo. They were told that the character loves zebras and thinks they are good but hates pandas and thinks they are bad (or vice versa, depending on the version of the questionnaire a participant received). Their task was to draw a zebra in the box that best represents good things like seeing zebras and a panda in the box that best represents bad things like seeing pandas (or vice versa).

The lefties largely drew the good animals in a box on the left-hand side of the page. The righties drew the good animal in the right box. It's a clear difference that's not replicated when Casasanto asked his participants to draw the animals in a vertical orientation.

Casasanto, 2009

In a replication of this test, he asked his participants to guess what he was trying to figure out. He writes that "99% of the participants were unaware of the purpose of the experiment," which suggests people aren't very aware that their bodies are guiding their behavior.

If you worry this research means lefties and righties can never understand each other, or agree what Fribble is the prettiest — don't. There are also spatial preferences that transcend hand dominance. Most people prefer "up" to "down," and first is better than last. (Which also explains why candidates listed first on a ballot tend to get a little bump. It's even plausible that George W. Bush won the much-contested 2000 Florida vote because he was listed first on the ballot.)

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