By Heather Kobayashi
Photo by Jeff the Trojan
There’s more to being a lefty than just which hand you write with. That sentence may sound wrong to some, but a growing body of research shows a many unexpected differences between different-handed individuals.
In everyday speech, there is seeming equivalence between “right” as opposed to wrong and “right” as opposed to left; however, there are some advantages to being “sinister,” or “gauche,” both originally words for left which have become pejorative in modern language. Left-handers have had disproportionate representation in the White House: including President Obama, 18.6% of US Presidents (8/43) have been left-handed, approximately double the percentage in the general population. Recent research also suggests that left-handers have a more accurate body sense than right-handers: when asked to estimate arm length, left-handed people estimated both arms as being the same length, while right-handed people tended to underestimate the length of their left arms. Similarly, left-handed people estimate that both of their hands are the same size, whereas right-handed people estimate that their right hand is larger. Researchers theorize that this difference indicates a variance in neural networks, the physical pathways of the brain, with right handed people devoting more brain matter to mapping of the right side of their bodies. Left-handed people, instead of having a larger brain map of their left sides, devote neural space about equally to both halves of their bodies–a decidedly less lop-sided approach. In fact, lateralization, as distribution of functions between the hemispheres is called, has garnered attention particularly where handedness is concerned.
Brain lateralization may relate to some of the disadvantages of being a lefty. Geschwind and Behen (1984) found a correlation between left-handedness and a host of immune and respiratory disorders as well as some learning and language disorders. They theorized that the diseases and disorders, brain lateralization, and handedness itself are all due to higher pre-natal testosterone exposure; however, they were also quick to speculate that there are some disorders which have lower occurrence rates among “sinistrals” and cited the higher than average rate of left-handedness in highly skilled professions such as architecture as evidence that left-handed people are not overall less intelligent or healthy. More recent research has cast some doubt on this theory, asserting that the hypothesis itself is ill-defined (Bryden, McManus, and Bulman Fleming, 1994). Geschwind and Behan failed to specify what levels of handedness and lateralization were supposed to correlate on the continuums of both scales and a meta-analysis of psychological research shows no particular support of the 1984 findings. Nevertheless, they still remain heavily cited because no stronger model of handedness has emerged. In addition, studies do show that lefties live, on average, 3 fewer years than their dexterous colleagues (Myers, 2007). This phenomenon may have its roots in–rather than a psychological difference–the greater number of workplace accidents that befall left-handed people because of mechanical systems designed for righties (a more severe form of the “there are no left-handed scissors” phenomenon in my kindergarten classroom). Identical twins often have different handedness, so some factor besides genetics must be in effect, but there is also high heritability of the trait (Myers, 2007). Thus, it remains unclear exactly how handedness, health, and the brain are related.
Then there are the ways in which being left-handed affects not the body, but perspective. In another recent study, researchers asked left-handed and right-handed people to place “good” or “bad” objects into one of two identical boxes. While right-handed people placed the good things in the right-hand box, left-handed people did just the opposite; this tendency was also reflected in product choices. (University of Granada, 2010) It appears that while right-handed people tend to associate rightness with rightness, as it were, left-handed people have the opposite associations. In this way, a simple change in sensory-motor experience seems to override cultural (linguistic) norms and simple spatial properties are linked to abstract concepts.
While some of these behaviors may seem trivial, they all point back to the infinite feedback loop which is the brain: behaviors shape neural networks which further influence behaviors. Neural patterns and pathways, formed by genetics and experience, shape actions both large and small, serious and trivial. Handedness is one of the many ways in which scientists can compare the way that different brains works and how that manifests itself in everyday life.
References
Association for Psychological Science (2009, November 5). Vast Right Arm Conspiracy? Study Suggests Handedness May Affect Body Perception. ScienceDaily. Retrieved March 5, 2010, from http://www.sciencedaily.com/releases/2009/11/091104152304.htm
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.
Geschwind, N., Behan, P. O., & Galaburda, A. M. (Ed.). (1984). Cerebral dominance : the biological foundations. Cambridge, MA: Harvard University Press.
Holder, M. K. (2009). Famous left-handers. Retrieved from http://www.indiana.edu/~primate/left.html
Myers, David G. (2007). Psychology (eighth edition in modules). New York: Worth Publishers.
University of Granada (2010, February 2). Right-handed and left-handed people do not see the same bright side of things. ScienceDaily. Retrieved March 5, 2010, from http://www.sciencedaily.com/releases/2010/01/100128101901.htm
It is interesting to note the social implication of handedness. For example, a left-handed friend of mine said he preferred buying notebooks with the spiral at the top, because it was difficult for him to write with the spiral on the left. I usually find that in a classroom, it is never the case that there are enough left-hander desks, but that right-handers get stuck in a lefty desk. Psychologically, I wonder how this acts upon left-handed people, even if for a small amount unconsciously.
On the subject of “sided-ness” comes a study at the Institute of Cognitive Neurology of the Modern University for Humanities that explored the concept of a leading eye. In this study, the participants were all right handed. Most subjects were right eye leading, but some were left eye leading. When reading text on the left side of a screen, the “left-eyed” persons performed better than their “right-eyed” counterparts. It can be concluded that since the right hemisphere of left-handed peoples’ brains control their left side, they were free from overlap with their leading hand’s movements. Perhaps this knowledge can be useful for making products oriented towards lefties.
Informnauka / Russian Science News Agency (2007, March 26). Are You Right Eyed Or Left Eyed?. ScienceDaily. Retrieved May 10, 2010, from http://www.sciencedaily.com /releases/2007/03/070323135954.htm
Comment by Psych 105 student — May 11, 2010 @ 4:16 pm
The difference in brain mapping between lefties and righties could have a more social cause than biological one. As Heather mentioned, there were never left-handed scissors and there are always too few left-handed desks. With a lefty forced to adapt to society’s right handed norms every day in life, it makes sense that the brain’s plasticity would quickly adapt. Individuals would begin to use their right hand for things because that’s the way that society has pushed them. I learned to throw with my right hand because when I played t-ball as a kid, there weren’t any catching gloves for lefties. These occurances are very common. It’s no wonder that we are forced to adapt in strange ways, leading us to have a more balanced brain than right handed individuals.
Comment by Clayton Masterman — May 18, 2010 @ 9:34 am
After reading this, I am eagerly awaiting a follow-up article concerning ambidextrous individuals as well as left handers forced to use their right hands. Are the brains of ambidextrous people even more balanced than left-handers forced to used their right hands to adapt in society?
As a left handed person, I expected that I would rely on my left hand more than my right, but as of now I use them fairly equally. I write with my left hand and eat with my left hand. But I use a normal computer mouse and throw things with my right hand.
Comment by Jon Lee — February 21, 2012 @ 1:09 pm
After reading this article on left-handedness, I became interested to do a little more research on my own accord. This post mentioned that sometimes identical twins would have one left-handed individual and one right-handed within the set. This seems to hint that environment has a role in which hand a person dominantly uses. It seems strange that by just being left-handed you have superior qualities. In a recent study, it was concluded that left-handed individuals make a statistically larger amount of money than right-handed individuals. Whether talent stems from being left-handed or being left-handed yields higher talented individuals is still a mystery to me and the general public; left-handed superiority is a very interesting topic that should be researched more extensively in the future as technology advances and continues to help solve these puzzling issues.
“Sinister and Rich: The evidence that lefties earn more”, by Joel Waldfogel. Appeared in Slate on August 16, 2006.
Comment by Evan Kamber — May 3, 2012 @ 4:41 pm
Like Jon, after reading this article, I’m also interested in a follow-up about ambidextrous people. My dad is ambidextrous and, growing up, I never realized how weird it must have been for him. He ate with his left hand, but table settings at restaurants were and are always for right-handed people. And as the Psych 105 student mentioned above, desks in school are nearly always for right-handed people. Our society has a preoccupation with defining what’s “right” by standards that many people, in this case left-handed people, have no hope of meeting. The Latin word for ‘left’ literally means ‘improper.’ My sister, for example, was left-handed when she first started learning how to write. And somehow, she grew right out of it: she’s right-handed now. That very well may have something to do with the fact that everyone else in her preschool class was right-handed and she wanted to be like them. Who knows for sure.
Comment by Taylor Nunley — September 19, 2012 @ 11:52 pm
These societal influences on left-handers also seem to impact their brain. Changing habits may seem like a simple thing if they are not engrained too deeply in the way the brain works (even then the brain has the ability to re-analyze and remap), but it is really interesting how closely our personalities are related to these changes.
A book written by Michelle Dresbold, who graduated from a secret service document examination training program, discusses how analyzing handwriting can indicate how a person is feeling temporarily, but also their more permanent character traits. This is because of the connection between the brain and handwriting. If someone’s personality changes there will be a difference in their script. Alternatively, changing handwriting can change a person’s brain, which would affect their personality. It surprised me that people could consciously alter, maybe not their overall personality, but their mindset by changing their style of writing.
Dresbold, Michelle. Sex, Lies, and Handwriting: A Top Expert Reveals the Secrets Hidden in Your Handwriting. New York: Free Press, 2006. Print
Comment by Maria Morris — September 26, 2012 @ 7:29 pm
A previous commenter’s question about ambidextrous individuals led me to do some more research on the topic; as a result, I stumbled upon a fascinating article by Michael Price for the Monitor Staff Journal. According to Price, the uneven lateralization of the brain that seems to accompany left-handedness or ambidextrousness has deep consequences. A gene that is frequently linked to schizophrenia is found on a gene most frequently found in left-handed or ambidextrous individuals; though left- and right-handed individuals score about the same on IQ tests, those who are ambidextrous score slightly lower; most fascinatingly, those who are ambidextrous are more likely to score high on what is referred to as the “magical ideation scale” – a scale used to measure the likelihood of an individual believing that, for example, they are somehow aware of when others are speaking about them.
Research seems to point to the fact that there are, in fact, negative correlations with left-handedness and ambidextrousness, but, as many others have pointed out, this seems to beg the question – how much of this is, in fact, genetic, and how much is social conditioning? I watched left-handed kids get teased throughout elementary school, and even in college, left-handed individuals are met with surprise when someone first observes them writing with their dominant hand. I myself am somewhat ambidextrous – I use my hands equally throughout the day, but each is used for a different activity (my right hand opens doorknobs, while my left opens bottles). However, this fact is rarely believed by others. When one grows up feeling that something is “off” about them – when one grows up being physically outside of the norm – what kind of effect does that have on the psyche? It was not so long ago that people believed that left-handedness needed to be “fixed”; the brain is a subtle organism, and things that we are not even aware are effecting us can often end up impacting us in the future more than we know.
Source: Price, Michael (2009). The left brain knows what the right hand is doing. Monitor Staff, Volume 40. Retrieved from http://www.apa.org/monitor/2009/01/brain.aspx
Comment by Anna Lieberman — October 11, 2012 @ 12:34 am
An interesting phenomenon this article reminded me of is that in the past, left-handed people were sometimes taught to treat their right hands as the dominant hand instead, thus training themselves to change handedness, or at least be ambidextrous. The last study mentioned in the article, about right-handed people associating “right” with “good” and left-handed people doing the same with “left,” was very interesting. I wonder if a left-handed person who had been trained to use the right hand for everything would still make that association (left=good), or whether, due perhaps to the brain’s plasticity, s/he would learn to think like a right-handed person, as well?
Comment by Jacqueline Krass — October 12, 2012 @ 8:37 am
Being left handed I instantly found this article to be interesting. Even though I am left I have adopted to some mannerisms that right handed people do. For example I am do not like left handed desk in classrooms. Since there is generally almost none in a class I have always used right hand desk and they are just more comfortable now. Other than the possibility of workplace accidents what else could be the potential reason for lowering the life expectancy of left handed people? Furthermore, though there is research in differences concerning left handed and right handed people has there been any significant research concerning people who are ambidextrous?
Comment by 105 student — October 12, 2012 @ 8:42 pm
Handedness has always fascinated me. Considering how left-handedness can feel disruptive to many people because it’s the norm, it’s interesting to consider its evolutionary utility. Doing some follow-up research, I found this article [1] in which Northwestern researcher Daniel Abrams states, “The more social the animal — where cooperation is highly valued — the more the general population will trend toward one side.” The proposed explanation? Tools are more easily shared when the majority of the population uses the same hand. So why then are there still millions of left-handed people? Some researchers believe it an advantageous adaptation for fighting. In this article [2], two researchers found a correlation between left-handedness and homicide rate in traditional societies. The found one of the highest rates of left-handedness (22.6 %) in the Yanomamo society of South America–where the murder rate is 4 in 1000. This can be compared the tiny proportion (3.4%) of lefties among the nearly pacifist Dioula-speaking people of Burkina Faso in West Africa, where the murder rate is .013 per 1000.
[1] http://www.ibtimes.com/science-how-why-left-handers-are-so-uncommon-916273
[2] http://www.economist.com/node/3471297
Comment by Karam Anthony — December 13, 2012 @ 6:52 pm