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.

13 Comments

1. 1. sparcboy 11:38 AM 1/3/12

   Mostly I agree with the words on the right side...

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2. 2. KSama 12:23 PM 1/3/12

   "Right-handers were asked to wear a bulky glove on their right hand, temporarily turning them into lefties. Participants began showing a “good-is-left bias."
   
   This would give a bit of credence to mothers who tie their childrens' hand to their bodies when they begin to show the 'leftie' preference. One might think then that this also gives credence to the 'conversion to or from homosexuality' hypothesis ? IE: homosexual conversion therapy
   
   "This year, three Canadian scientists published a study which found some connection between left-handedness and homosexuality (1).
   
   Analyzing a number of studies, their paper concludes that male homosexuals are about one third (31%) more likely than heterosexuals to be left-handed (2), while lesbians are almost twice as likely (91%) to be left-handed as heterosexual women."

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3. 3. thevillagegeek 02:15 PM 1/3/12

   How about a link or other source so we can evaluate it for ourselves?

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4. 4. Not 'Tarded 02:48 PM 1/3/12

   Ok, so how about Ambidextrous peoples?
   It would follow that they show no bias - equally picking left or right, based on?
   
   Would be curious to hear more about this...

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5. 5. ColleenHarper 04:26 PM 1/3/12

   Early in reading the article, I started wondering about any affects a change in handedness would play in the research, and the author addressed that issue quite clearly.
   
   About 13 years ago, I put my right hand through a glass door, severing nerves, tendons, muscle bundle. I did a nasty job to it. Today, I have significant use of the hand in some ways, but at only about 75% of what I had, with permanent loss of sense of touch. So today, I tend to be more left-handed, and thinking about the study's results, I had to agree that it seemed to apply to my condition. Very interesting!

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6. 6. KSama in reply to ColleenHarper 10:21 AM 1/4/12

   "it seemed to apply to my condition. Very interesting!"
   
   You took up hunting and changed professions to welding ?

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7. 7. ErnestPayne 02:08 PM 1/4/12

   Well one observation is that there are a higher percentage than normal of left handed people being stamp collectors. The person handling my pension claim was left handed and, on a hunch, I asked him, out of the blue, what he collected. Sure enough he was a collector (but not of stamps).

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8. 8. MikeB 02:39 PM 1/4/12

   As a career left-hander I believe fully that lefties do, in fact, parse reality differently from righties. Years ago when I was inteviewing job candidate I could usually pick out the southpaws by the way they approached problem-solving exercises. Righties would immediately identify a strategy and pursue it, while lefties would circle around for a while before deciding on a course of action.
   
   Maybe it's a good thing for the president of the US to be circuitously ratiocinative. Gerald Ford, the senior Bush, Clinton and Obama are all lefties. Reagan seems to have been ambidextrous, perhaps because he was forced to write with his right hand according to the custom of his schooldays. Certainly lefties are disproportionately represented among presidents.

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9. 9. witch_ink 12:19 PM 1/5/12

   I was born left handed in the mid 50s, and until first grade was mostly free to write and draw with whichever hand. In first grade I was told (ordered) to write with my right hand, in class and at home; when I brought in homework that was well-written the teacher knew I had written it with my left hand. In class my left hand was loosely tied behind my back, with all the other kids in the class making fun of me...You can imagine how much fun going to school was in first grade! My mother was of course furious and raised hell with the school, but I'd already started my road to ambidextrism.
   In art class I was either allowed to use my left hand or the teacher gave up, I'm not quite sure which, since art was not considered as vital as writing letters or doing arithmetic.
   As for decision making: I make quick and decisive choices, but am also very good at thinking out of the box; as a 'type A' I get things done, in life as in work, and stick to projects to the end, but am also creative and may do things in a roundabout way: the result is what matters to me. I read several books on different subjects at the same time, sketch in china ink, cook semi-professionally.
   I can usually see both sides of a discussion or argument, I understand people as much as I do animals ( I'm an Anthropology undergrad, back in college, also have a pet sitting business and two Shar-Peis).
   I have often wondered if this forced switch could have had any effect on my brain circuitry: I was already reading at 3 when still only a 'southpaw', taking my fluffy toy pink bunny to our library, sitting on the floor with all the encyclopaedias and reference books. I remember writing words with crayons on paper, then asking mom or dad what they were, and drawing pictures of what some words made me 'see'. Did my 'quirkyness' (as friends politely call it) come from becoming something I wasn't born to be? Have I always been able to sense things differently than others? Is my sleep paralysis, with all the terrifying times this has happened as a child and even (less) now, genetic or did reorganizing the left and right side of my brain to stupidly conform mess with my life?
   Ambidextrous bias: I still reach for things with my L hand, use my fork with my L hand, draw with my L hand - I take cards from my wallet with my L hand (swipe with my R hand only because machines are set up that way) and also pay with L hand - I like my textbooks, papers etc., on my L side and my coffee on my R side. Ads annoy me on either side. I'm heterosexual, married, female, don't collect stamps

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10. 10. Spin-oza 02:23 PM 1/5/12

    WOW... earth-shaking research and findings... not!
    Of course we have developmentally determined predilections and tendencies. I would be quite surprised were there absolutely NO tendencies to orient or shape our environment into some preferred arrangement.
    The fact that our brains at some point in evolution, due to limitations of the cranium began (right and left) hemispheric specialization has lead to a dominant eye... as well as dominant handedness, among other phenomena.
    It would also be interesting to know if the dominant eye and hand have a additive or synergistic effect.

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11. 11. witch_ink 12:08 PM 1/6/12

    @Spin-oza "WOW... earth-shaking research and findings... not!
    Of course we have developmentally determined predilections and tendencies"
    
    I'm so pleased that you stated the obvious, and so elegantly brought nothing new to the forced ambidextrism comments. As for the dominant eye/hand connection, experiments involving, for example, aiming accuracy can easily be conducted. Assuming you are familiar with the scientific method, use all the hand/eye combinations, and correlate data correctly you should have an answer to your:
    "It would also be interesting to know if the dominant eye and hand have a additive or synergistic effect."
    
    
    

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12. 12. Spin-oza in reply to witch_ink 01:06 PM 1/6/12

    Ahhh... perhaps i should have taken the tack of self-indulgent, verbose, auto-biographical-babble that you took?
    
    Clearly the point of my post eluded you... completely... "witch" is to say that i believe it was the brute fact of our evolved cerebral hemispheric lateralization that has lead to such neuro-spacial-psychological "tendencies" - and it would only be surprising if these "biases" did not exist.
    
    There many far more interesting neuro-psychological phenomena revealed in the study of commisurotomy patients for example (i.e. "split brain" - "neglect")... plus "phantom limb"... etc.
    These are all expressions of the neuro-anatomical basis of "consciousness", or what the late Sir Francis Crick termed "The Astonishing Hypothesis"... which at this juncture, seems rather obvious.
    
    The mildly interesting finding, again common in neuroscience, is the "plasticity" of these "choice" tendencies based on short-term modifications of limb use. But then again, evolution has favored such adaptability, eh?
    
    Here's what I found interesting from the article:
    "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."
    
    Finally, the fact that marketing execs wish to use these data for crass financial gain, is of course, the least surprising of all... and politicians can't be far behind!

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13. 13. majako 09:33 AM 2/1/12

    I am right handed, and when i look, for example at someones FB timeline, or at restoram menu, all I see is the left side of that! So... I belive it may give some people some slight preferences, but othervise...

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