| Abstract: |
Left- and right-handed individuals have different brain structures,
particularly in relation to language processing. Using five data sets from the
US and UK, I show that poor infant health increases the likelihood of a child
being left-handed. I argue that handedness can thus be used to explore the
long-run impacts of differential brain structure generated in part by poor
infant health. Even conditional on infant health and family background,
lefties exhibit economically and statistically significant human capital
deficits relative to righties. Compared to righties, lefties score a tenth of
a standard deviation lower on measures of cognitive skill and, contrary to
popular wisdom, are not over-represented at the high end of the distribution.
Lefties have more emotional and behavioral problems, have more learning
disabilities such as dyslexia, complete less schooling, and work in less
cognitively intensive occupations. Differences between left- and right-handed
siblings are similar in magnitude. Most strikingly, lefties have six percent
lower annual earnings than righties, a gap that can largely be explained by
these differences in cognitive skill, disabilities, schooling and occupational
choice. Lefties work in more manually intensive occupations than do righties,
further suggesting that lefties' primary labor market disadvantage is
cognitive rather than physical. Those likely be left-handed due to genetics
show smaller or no deficits relative to righties, suggesting the importance of
environmental shocks as the source of disadvantage. Handedness provides
parents and schools a costlessly observable characteristic with which to
identify young children whose cognitive and behavioral development may warrant
additional attention. |