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Economists are increasingly interested in understanding how cognitive and non-cognitive skills contribute to individuals’ success in the labor market. In his recent research Joshua Goodman, assistant professor in public policy, considers how the brain structures of right and left-handed people might have bearing on workplace performance and how this correlation could be used to inform policy.
Q: Please describe your research on handedness and how and why you got interested in this topic.
Goodman: This all began when I was trying to come up with ideas for undergraduates, who sometimes come to me seeking ideas for their theses. I happened to notice in some data sets that labor economists’ work with that, bizarrely, they happened to ask the question about whether a person is right or left-handed, and I thought here would be a simple project for a student to work on, to ask whether left and right-handed people have different outcomes in life. Do they get different jobs? Do they have different incomes? Do they complete different amounts of education?
Unfortunately none of my undergraduates were interested in pursuing this project, so I began playing with the data. I was expecting to either see nothing particularly interesting or to find evidence backing the commonly held perception that lefties are generally smarter or more creative than right-handers. But what I actually began seeing in the data were fairly consistent patterns, across a whole host of outcomes, showing that left-handed people looked somewhat disadvantaged relative to right-handed people, and that got me interested in pursuing this project a little bit further.
Q: What impact could this research have on public policy?
Goodman: The central results that I find are that on average left handed people score a little bit lower on math and reading exams than right handed people; they are a little less likely to complete college; and when they go out into the labor force, they earn about 10% lower incomes than right handed people, partially because there are a significant number of left handed people who don't end up working at all.
All of these results surprised me, but as I began to learn a little bit more about what biologists and the medical community know about left handedness, I realized that perhaps it's not so surprising. Left-handed people have somewhat different brain wiring than right handed people do. Left-handers in particular, on average, process language in a different hemisphere of the brain than right-handed people. It turns out they are more likely to be dyslexic than right-handed people are. They are more likely to have more learning disabilities and this may help explain some of the differences that you see in math and reading scores between right and left-handed people.
As I began to explore this further, I thought that this was not really about whether or not you use your left hand to write or to hold scissors; it really may be more that handedness reflects some deeper underlying structure in terms of your brain wiring.
That in and of itself doesn't clearly have policy implications, but I also found something interesting both in my data and in certain other medical studies. It turns out that handedness is not completely outside of the control of individuals; there is a component that is genetic. For instance, my wife who is left-handed, has two left-handed parents, and this is not a unusual pattern, so there is a genetic component. But there is also an environmental component of handedness. And what I see in my data and what others have observed in their studies is that children who have poor infant health, who are low birth weight, or whose mothers have gone through serious stress while they are pregnant are more likely to give birth to children who are left-handed.
So it seems that there is actually some component of brain wiring that is determined by environmental influences such as stress to the mother during pregnancy. And that's where I begin to think that there may be some policy implications here. This is one in a line of papers showing that environmental influences when kids are young or even in utero can have serious long term impacts on their lives.
Q: Has there been any concern that this research might influence hiring in a negative way when it comes to left-handed people? Sometimes there is criticism around “predictive” research – for example, the possible negative impact of identifying a predisposition for a particular disease. What would you say to such criticism in relation to your research on handedness?
Goodman: One thing it’s important to understand: in my data I do see statistically significant differences between lefties and righties. But by the time a person is an adult, a potential employer has a huge amount of information about the person in front of them – whether they completed high school, whether they completed college, previous work experience, a whole host of measures of their abilities – and once they have that information, knowing whether a person is left or right-handed actually will not indicate to an employer any kind of new information.
What I see my study being more important for is, for example, when you have a young child, a two-, three-, or four-year old who has yet to go off to school, but it’s already clear whether they are left- or right-handed. For example, I have a son who is about 15 months old now. If it turns out that he's left-handed, I will pay a little bit closer attention early on to make sure that he’s learning his alphabet, learning his numbers, that things are going well, because I’ll know that he is at a somewhat heightened risk for learning disabilities such as dyslexia.
When a kid is young this may help identify vulnerabilities, but by the time someone is 18 or 25 looking for a job, this particular aspect of their lives will not actually tell employers much given what they will already know about them from their resume.
Q: Are there educational policy implications from this research?
Goodman: My view is that, particularly early on if I were a school and I had young kids – kindergartners, first graders – enrolled, and I knew that some subset of those kids were left-handed, I would use that to pay a little bit more attention to those children just to make sure that they were developing in the way that I would expect a child of that age to develop. Again, the increased risk for problems, though it's statistically significant, is not huge. It's not that you should worry if your child is left-handed, but you might want to pay a little closer attention. So I would see that as helping schools that deal with very young kids, just catching at an early age, might a kid get a slightly elevated risk for something like dyslexia?
I might also say from a policy perspective this does point out the challenge that given that what I see in my data is that the way that your brain is wired from birth has very important impacts on how you do in school and subsequently life outcomes. It does point to the fact that actually even once the kid arrives in school as a five- or a six-year-old, there are a whole host of factors that are already beyond the school's control. So as we think about education policy in this country or labor market policy, we may want to pay more attention than we do to the kinds of factors that affect kids when they're very young, even when they're in utero – so things like mothers' health, infant health, for example. That's what I see the implications of this research pointing toward.
Q: From the health policy perspective, what do you feel is the most important impact of this research?
Goodman: I think that this research fits into a set of papers that have been written over the past five or ten years by health economists that have shown very clearly that environmental influences on kids when they're quite young, including in utero, can have serious long run impacts on their life outcomes. So it's not always precisely clear what the policy implications are here, so we don't always know what exactly are the kinds of stresses and environmental factors that mothers experience that might create problems with their children's health at a very young age, but it does point to the importance of paying attention to infant health and to pre-natal care and to the kind of environments that pregnant mothers experience. So I think if anything it highlights that we need to pay attention to kids from the moment they begin to develop because very early influences can have very long run impacts.
Q: How does this study fit into your academic body of research?
Goodman: This is a quirky piece of research. As I said, I started it a little bit on a whim, and as I began to explore the topic of handedness I realized more and more that this was just an absolutely fascinating area. It's very rare – with the kinds of data used by education policy folks and labor economists – that we can actually tap into something as deep, as fundamental to a human being's biology as the way their brain is wired. We just don't have data sets that ask those kinds of questions. Doctors do, but they do it with very small data sets where they scan people's brains with FMRI machines. That's not something that most economists do with large data sets where we know how people are doing later in life.
So this research was just an extraordinary example of one way that we could identify a sub-set of people who are very likely to have somewhat different brain structures.
And so I have to admit this doesn't fit so squarely with the rest of the research I do in education policy. The rest of my research has much more to do with things like: should we force kids to do more math in high school? Or should we make kids attend more school, have longer school years, or fix absenteeism problems? I don't see these things as terribly closely connected.
To me, what this particular piece of research shows is that there are certain forces that are largely outside of the control of schools, so that if we want to think about helping kids develop their full potential, we not only want to think about what happens in schools, but what happens to them even earlier in life.