Daniel Voyer, Ph.D.,

Daniel Voyer Ph.D.

Perceptual Asymmetries

Clumsy Left-Handers: Fact or Fiction?

Many people seem to believe that left-handers are clumsy. Is that true?

Posted Mar 31, 2015

There seems to be an ingrained belief in our world that left-handers are clumsy. In fact, I expect that if you asked anyone what the most enduring trait of left-handers is, they would likely tell you that they are injury prone klutzes. In my native tongue (French), this is even part of language as the word “gauche” is used to refer to someone as a klutz and it is also the direct translation of the word “left”.

As a left-hander, I have lived with this view all my life. For example, when I was a graduate student, I was even introduced to a famous person in my research area as “that clumsy left-hander” by my PhD supervisor, the late M. P. Bryden. Dr. Bryden was an expert in the field, who definitely had a clear understanding of what left-handedness entails so he knew what he was talking about. Of course, in context, you have to know that I had just missed about a week of lab attendance because I had dropped a block of concrete on my foot! Perhaps I deserved that introduction.

At least, I now know that this view of left-handers reflects the presence of a stereotype of left-handedness (Grimshaw & Wilson, 2013). Still, should we believe that this injury I inflicted on myself was something that should be expected as typical for someone like me, who uses the left-hand for a majority of unimanual activities?

For starters, data do show that left-handers tend to die younger (Coren & Halpern, 1991). Perhaps it is because they also tend to have more accidents. However, Coren and Halpern do mention that environmental factors might account in part for the higher number of accidental deaths in left-handers. Specifically, much of the machinery we use is designed for safe use by right-handers, which often introduces a safety risk for left-handers. For example, when I use an electric circular saw, I hold it with my left hand while holding the piece of wood I am cutting with my right hand. The way such a typical saw is built, this puts my right hand within centimeters of the cutting blade, thereby increasing the risk of a serious injury to that hand. In contrast, if you hold the saw with your right hand, your left hand holding the wood is protected by the bulk of the motor. This reduces the risk of a hand injury in right-handers Therefore, left-handers have to be particularly careful in what is essentially a hostile world for them and this might explain in part why they tend to die younger. From this perspective, left-handers could be seen as an oppressed minority in a world of right-handers!

As an aside, I feel that it is important for me to mention that much of the speculations about neuropathology linked with left-handedness that are presented as other possible factors to account for the reduced life expectancy of left-handers by Coren and Halpern have been criticized and mostly discounted by Bryden, McManus, and Bulman-Fleming (1994), among others. This means that environmental factors might be the main culprit although, as a left-hander, I might be trying to convince myself!

When we start considering more closely the association between hand preference and risk of injury, the pattern of findings is not clear cut. Some authors do report that left-handers are more likely to suffer injuries that require medical assistance (Bhushan & Khan, 2006) whereas others report that it is a question of degree of handedness, not direction (Mandal, Suar, & Bhattacharya, 2001). Specifically, it would not be whether you are left- or right-handed that matters, but how strong your hand preference is, regardless of its direction. In particular, individuals with a weaker hand preference (like me!) should be more liable to have accidents than those with a strong hand preference. Such findings are typically interpreted as reflecting poorer integration of conflicting sensory information from the two cerebral hemispheres in weak-handers, resulting in accidents in the environment. This means that keeping sensory information relatively separate in the two hemispheres may result in fewer accidents.

This last view suggests that relying solely on hand preference as a predictor of injury liability might be misleading as handedness is not necessarily linearly related to hemispheric asymmetries. With this in mind, Voyer and Voyer (2015) included verbal and nonverbal measures of hemispheric asymmetries in addition to measures of hand preference. Somehow, this step had never been taken as previous research focused exclusively on hand preference as an indirect measure of hemispheric asymmetries. Although their measure of hand preference suggested direction of handedness as an important factor (i.e., left-handers did have more accidents), they found that the more direct measures of cerebral specialization supported degree of handedness as crucial. Specifically, weak lateralization on the direct measures was associated with more accidents, indicating that individuals with weak rather than strong hemispheric specialization were more prone to accidents. Interestingly enough, there was no association between the hand preference score and laterality scores on their direct measure of hemispheric asymmetries.

The study by Voyer and Voyer (2015) showed that the stereotype of the clumsy left-hander might be a myth. However, watch where you are going if you hang out with a weakly lateralized person. Of course, you might not know until you give them a test of perceptual asymmetries, or until it is too late!

By the way, 25 years after the incident, the foot on which I dropped the concrete block still hurts on cold, damp days. Another long lasting consequence of my weak cerebral lateralization!

References

Bhushan, B., & Khan, S. M. (2006). Laterality and accident proneness: A study of locomotive drivers. Laterality, 11(5), 395-404.

Bryden, M. P., McManus, I. C., & Bulman-Fleming, M. B. (1994). Evaluating the empirical support for the Geschwind-Behan-Galaburda model of cerebral lateralization. Brain and cognition, 26(2), 103-167.

Coren, S., & Halpern, D.F. (1991). Left-handedness: A marker for decreased survival fitness.  Psychological Bulletin, 109, 90-106.

Grimshaw, G.M. & Wilson, M.S. (2013). A sinister plot? Facts, beliefs, and stereotypes about the left-handed personality. Laterality, 18, 135-151.

Mandal, M.K., Suar, D., & Bhattacharya, T. (2001). Side bias and accidents: Are they related? International Journal of Neuroscience, 109, 139-146.

Voyer, S. D., & Voyer, D. (2015). Laterality, spatial abilities, and accident proneness. Journal of Clinical and Experimental Neuropsychology. doi: 10.1080/13803395.2014.985191

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