The Upper Hand

by David Johnston.

About 10 percent of the population is left-handed. However, five of the last seven U.S. presidents have been left-handed, as well as many high profile artists and scientists – from Paul McCartney and Lewis Carroll to Benjamin Franklin and Marie Curie. This large collection of gifted left-handers has led to a widely-held belief that left-handers have a higher propensity for genius and creativity than right-handers. Two recent economics studies have provided some limited support for this belief. Kevin Denny and Vincent O’ Sullivan find that left-handed men in Britain earn approximately 5 percent more than right-handed men, and Christopher Ruebeck and colleagues find a similar wage premium for left-handed men in the United States.

Historically though, handedness has been repeatedly associated with abnormality and evil. A clear example of this association is that the English word sinister comes from the Latin word for left. There was also a belief that left-handers were clumsier than others. The early 20th-century psychologist Sir Cyril Burt stated: “Not infrequently the left handed child shows widespread difficulties in almost every form of fine muscular coordination. Awkward in the house and clumsy in their games, they are fumblers and bunglers in almost everything they do.” Furthermore, there exists a large medical literature associating handedness with a number of illnesses, such as hypertension, arthritis, autism, schizophrenia, brain tumours and breast cancer (though, there is much inconsistency of results in this literature).

If left-handers are truly more likely to be geniuses as many believe, or more likely to be clumsy fools as has been often suggested in the past, then it should be most clearly evident in children – before left-handers are discriminated against in a world that is substantially geared towards right-handers. To this end, my co-authors and I compared the performance of left- and right-handed children both in Australia and in the United States and found some striking results.

In 2004, five thousand Australian children aged 4 and 5, as well as their parents and teachers completed detailed surveys for the Longitudinal Study of Australian Children. Importantly, the children’s development was assessed in a number of ways and their handedness recorded. A statistical analysis of this survey data revealed a clear pattern – left-handedness is associated with much lower levels of ability.

A broad range of skills were assessed, including vocabulary, reading, writing, copying, social development, and gross and fine motor skills. Left-handed children performed worse than right-handed children on nearly all measures. Also, the differentials are large, with left-handed children 7 percentage points less likely to be rated as ‘competent’ by their teacher than right-handed children. This effect is similar in size, though opposite in sign, to the effect of mother’s having a university degree. Interestingly, we also find evidence of gender differences, with left-handed boys faring relatively worse than left-handed girls. Importantly, these differences cannot be explained by different socioeconomic characteristics of parents or different investment in learning resources in the household, and were not limited to tasks that require a fine motor response, such as writing.

In addition, an examination of the distribution of ability revealed a general reduction in ability relative to right-handers, without any change in the shape of the ability distribution. If left-handers are overrepresented among gifted children, there should be an excess of left-handers in the upper tail of the distribution. We found no such pattern.

While left-handers performed more poorly than right-handers, the most disadvantaged group was in-fact children with no hand preference (mixed-handers). The degree of disadvantage for mixed-handers was roughly double the disadvantage of left-handers relative to right-handers. This finding should be viewed with caution, however, as it’s possible that children with mixed-handedness are developmentally delayed in relation to their hand preference and ability, and this has little to do with laterality per se.

Another caveat for these Australian findings is that we were unable to rule out the possibility that some unobserved family traits were the root-cause of the ability differences, or the possibility that these differences would diminish or even change sign with age. So, in order to rule out such possibilities we also examined U.S. data that allows for the comparison of the performance of same-sex siblings across time (from ages four to fourteen) on tests related to memory, vocabulary, mathematics, reading and comprehension.

Preliminary research with this data suggests that the same left-handedness deficiencies we find for Australian children exist in the United States – left-handed children (especially boys) scored significantly lower than their same sex siblings in all tests. Furthermore, the size of the differential does not seem to change with age.

In many ways, this research refutes the commonly held belief, supported mostly by anecdotal evidence, that left-handers are high-achievers. It instead confirms the historical point of view, that on-average left-handers have lower cognitive abilities than right-handers.

This research is from a forthcoming article in Demography, titled “Nature’s Experiment? Handedness and Early Childhood Development”, and is co-authored by David W. Johnston, Mike Nicholls, Manisha Shah, and Michael A. Shields.

Dr David Johnston is a researcher and teacher at QUT’s School of Economics and Finance.

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12 Responses to “The Upper Hand”

  1. Ed Says:

    An interesting commentry, but one is left feeling what is the point, a call to arms to the rightisms of the ’50’s perhaps.

    As a leftie circa 1956, I recall the punitive measures used to ‘correct’ my errant behaviour, hours of detention where I was forced to transcribe documents with pen and ink, a particularly difficult task for the lefty with their propensity to smear the damp ink with a trailing wrist, never of course an issue for the ‘righties’.

    Over time my intrasigence in maintaining my handedness culminated in weekly canings: always the left hand to remind me of my folly.

    The sporting field was a further challenge, ‘though I was a ‘killer’ batter and bowler in the school yard, and owner of many shooter marbles, at PE I was a laughing stock as my errent right hand tossed pathetic salvos easily countered by even the polio-sufferers in my assisgned challenged group.

    But we surpass the schoolyard, and times change…or do they…
    As noted above, even now, left handed boys are worse off than similarly gifted girls, but is this news! Many commentaries note that achievement scores for girls exceeded those of boys in all measured academic categories in the 1990’s.

    But back to the above; in the past and remaining to the 1950’s and 1960’s, my formative education years, being left-handed was actively discouraged, so perhaps those able to make it through the mill were better prepared for the challenges of later life. Hence the anecdotal advantage of the left-handed may well be a true but transient phenomena lost to the ‘enlightened’ changes to the education system.

    Ed

  2. Long Suffering Says:

    Does Ed’s hypothesis mean that there were economic productivity gains from getting lefties to convert to righties that are not now available? Where else does the economics come in? Surely making both left and right handed scissors, golf clubs and stubbie holders means that costs go up because economies of scale are reduced? Are lefties paid less than righties?

  3. Fred Says:

    Surely there are too many variables in the upbringing of a child, Ed’s treatment notwithstanding, that makes it virtually impossible to determine the “success” (definition required) of a child 🙂

  4. Righty Says:

    In response to Michael – I had to look up a few words in Ed’s as well. Intracsigence means not being flexible and uncompromising. So he got the cane for refusing to conform. http://dictionary.reference.com/browse/intransigence

    My mother (a lefty) only missed out on the cane because she was a girl. We could also look at the social implications of such things, the inability of lefties and righties to pass on some manual skills as immitation and sharing of tasks can be much harder eg knitting and my mother’s inability still to know which side of the plate the knives and forks are situated. Or perhaps that is a sign of her intelligence….

  5. Sinister AO Says:

    Your sample is biased, irrelevant, and quite useless. The institutions that are primary and secondary school are right handed institutions. How? It is well known that left handers use the right side of the brain which is the creative side. Right handers use the left side of the brain which is the analytical side. Primary or High school does not promote creativity. Primary and high school actually denounces creativity hence the school uniforms and rigid structure. So to give a creative left hander a test on school subjects is actually extremely useless in trying to prove or disprove that left handers are gifted. To put it simply, school is the natural habitat of a right handers brain, but is a foreign habitat to a left handers brain. So it is no wonder the lefties fared lower than the righties in your tests.

    Furthermore, it is no secret that primary and secondary school have barely any relevance to the real world. The real world appreciates creativity. Innovation, efficiency, and design are products of creativity.

    So your tests reveal that left handers have a so called ‘lower-ability’ IN school. Unfortunately this is the real world, and the real world appreciates creativity and NEEDS creativity to advance. Therefore your data has proven or disproven nothing. Perhaps if you were a little more creative you would have found better data to analyse than results of ‘school exams’. Perhaps something based on the real world.

    To put it simply, the world needs creativity, which happens to be the natural habitat of a left handers’ brain. Thats why we are gifted.

  6. David Says:

    In response to Sinister AO – Our sample of children are aged 4 and 5, and have not yet been to school! Therefore, the fact that “primary and secondary school are right handed institutions” would not bias our results.

    The test scores used are from a test designed by the survey organisers, and examines children’s ability in reading, writing, copying, and symbol recognition.

    The children’s kindergarten teachers also rate the children in a variety of domains: (1) social/emotional development (e.g., adaptability, cooperation, responsibility, and self-control); (2) approaches to learning (e.g., attention, observation, organization, problem-solving); (3) gross motor skills (e.g., running, catching and throwing balls, strength, and balance); (4) fi ne motor skills (e.g., manual dexterity, using writing and drawing tools); (5) expressive language skills (e.g., using language effectively, and ability to communicate ideas); and (6) receptive language skills (e.g., understanding, interpreting, and listening).

    Left-handed children perform worse in all outcomes.

  7. Sajid Says:

    I do concur with these findings. My son,5 is left handed and when compared to my daughter, 7 who is right handed. The challenge is to add extra training at home to bring them to par with the remaining class.
    I need more information what additional training can one do to assist them.

  8. Creativity in Education Says:

    In the business world, creativity = innovation. Business Week last month had a article discussing how companies with formal innovation processes or reward programs had fewer innovations or patents than companies that did not. Of course, the article is probably biased towards larger companies that have thousands of complacent, risk-averse employees and the resources to build a corporate innovation program. Smaller companies, trying to differentiate, may have a better hand at innovation.

    I do see similar parallels between schools and businesses as far as creativity/innovation is concerned.

    John

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