Although I am right-handed, I recall wondering about my left-handed colleagues when I was a biochemistry student in Chile. I had the perception that being left-handed was a common trait among scientists-to-be. Later, as a graduate student and then as a postdoc, I had the same feeling. I still don’t know if I was right, actually I am more confused than before.

While waiting for a two-hour incubation, I checked some references and decided to make a survey on the same Web site that the PDA uses. It wasn’t as easy as I first thought! The free version only allowed a very simple format. I finally decided to ask only a few questions to be able to analyze the output more quickly. I particularly asked for gender information since apparently there are more left-handed men than women.

I want to thank all the 355 people who took the time to answer. After 100 people answered, I ended up paying a twenty dollar fee to upgrade my Web account in order to be able to receive more answers. That’s probably how a free Web page makes money.

If only scientists (327 in total) are considered, nearly 18% of men and 15% of women are left-handed (see figure). This is above the population average, but nothing spectacular—roughly 10% is left-handed (reviewed in M.C. Corballis, Behav. Brain Sci. 26, no. 2 (2003):199-208 PubMed Link).

Unfortunately, as many of my colleagues pointed out, this result has a selection bias. Left-handed people, for whatever reason, would be more compelled to answer. I personally think it is because this is a subject that is interesting to them. Although somebody pointed out that left-handed people would feel proud of their success in becoming a scientist despite discrimination, I hope this is not the case for younger generations as discrimination on the basis of handedness is one of the many terrible mistakes of education. Indeed, a few people answering the survey told me later that they were re-educated in school to become right-handed.

Talking about comments, I had to delete them all. Why? This is another thing I learned from this experience—I was actually doing research on human subjects. No matter how bad my research was, I had to write a letter to the Institutional Review Board, promising not to obtain the identity of my “subjects.” Since that information was present in some of the comments, all of them were deleted. Sorry! The good thing is that I am no longer in violation of NIH rules regarding human subjects research.

I also learned that the best way to avoid bias is to ask something else to disguise the question. Someone (not identified, of course) suggested that Human Resources should ask the question to every new employee. I hope they are reading this. Another way would be to ask how many left-handed and right-handed people are in each lab. I could just have asked in a few labs, to control my data, but that would reveal the secret identities of my colleagues. In my lab, 12.5% are left-handed, not so far from the population average. What about your lab?

Further reading: The number of articles in PubMed is impressive. There is even a journal called Laterality. The articles range from interesting, sound science to the really bizarre—searching for links between handedness and smoking, and even delinquent behavior. For those interested in re-education of handedness, there is an interesting NMR study, S. Kloppel, et al., “Can Left-handedness Be Switched? Insights from an Early Switch of Handwriting,” J. Neurosci. 27, no. 29 (2007):7847-53 (PubMed Link).