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What Hand You Favor Shapes Your Moral Space

Being right- or left-handed affects your psychology in many ways, recent research shows



iStock/chuwy

You’re out to dinner at a restaurant that just recently opened. Steamed mussels or steamed calamari? Three cheese ravioli or eggplant parmesan? Strawberry cheesecake or chocolate mousse? With so many good choices, how to decide?

A series of studies led by psychologist Daniel Casasanto suggests that one thing that may shape our choice is the side of the menu an item appears on. Specifically, Casasanto and his team have shown that for left-handers, the left side of any space connotes positive qualities such as goodness, niceness, and smartness. For right-handers, the right side of any space connotes these same virtues. He calls this idea that “people with different bodies think differently, in predictable ways” the body-specificity hypothesis.  

In one of Casasanto’s experiments, adult participants were shown pictures of two aliens side by side and instructed to circle the alien that best exemplified an abstract characteristic. For example, participants may have been asked to circle the “more attractive” or “less honest” alien. Of the participants who showed a directional preference (most participants did), the majority of right-handers attributed positive characteristics more often to the aliens on the right whereas the majority of left-handers attributed positive characteristics more often to aliens on the left.

Handedness was found to predict choice in experiments mirroring real-life situations as well. When participants read near-identical product descriptions on either side of a page and were asked to indicate the products they wanted to buy, most righties chose the item described on the right side while most lefties chose the product on the left. Similarly, when subjects read side-by-side resumes from two job applicants presented in a random order, they were more likely to choose the candidate described on their dominant side.

Follow-up studies on children yielded similar results. In one experiment, children were shown a drawing of a bookshelf with a box to the left and a box to the right. They were then asked to think of a toy they liked and a toy they disliked and choose the boxes in which they would place the toys. Children tended to choose to place their preferred toy in the box to their dominant side and the toy they did not like to their non-dominant side.

Casasanto has also shown that body specificity is malleable. When participants were forced to temporarily use their non-dominant hand, their natural bias flipped to associate positive qualities with the side they were forced to use. In a recent study, adult right-handers were asked to wear a bulky glove on their right hand, temporarily turning them into lefties. After a short period of time, participants began showing a “good-is-left” bias like natural lefties, placing items thought to be “good” in a box to their left. This suggests that changes in motor experience can change the direction of the body-specific bias in a matter of minutes.

These results have potentially lucrative implications for marketing strategy. Approximately 70 to 95 percent of all people are right-handed. Would companies be able to better market their products by placing their products on shelves or billboards to the right of their competitor’s products? Should companies vie to have their advertisements placed to the far right on web pages?

These experiments also raise an important question for artificial intelligence: If our cognition and decisions are partially rooted in how we use our body to navigate our environment, will intelligent machines of the future require a physical presence in order to match human intelligence? Some neuroscientists believe that motility was a major driving force in the evolution of the brain. It might be the case that even forms of intelligence based on silicon will not get far without a physical world to explore.

Are you a scientist who specializes in neuroscience, cognitive science, or psychology? And have you read a recent peer-reviewed paper that you would like to write about? Please send suggestions to Mind Matters editor Gareth Cook, a Pulitzer prize-winning journalist at the Boston Globe. He can be reached at garethideas AT gmail.com or Twitter @garethideas.

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