December 7, 2014 report
Earnings show less for left-handed, says study
Much has been thrown at left-handed people—they are quick to anger, quickly scared and, with the exception of heads of state, are more or less life's losers. Much too has been bestowed upon left-handed people—they are creative and score highly on certain tests. Obviously, scientists need to rely on more than popular notions to make connections, if any, between left-handed people and success.
A recent attempt in that direction is a paper published in the Journal of Economic Perspectives, "The Wages of Sinistrality: Handedness, Brain Structure, and Human Capital Accumulation," by Joshua Goodman, who holds a PhD in economics from Columbia University and is assistant professor at Harvard's Kennedy School. Those looking for confirmation that left-handed people are more fortunate than right-handed people will not be heartened by Goodman's research.
About 12 percent of humans are left-handed, with higher rates for males than females. Goodman said that compared to righties, lefties score a tenth of a standard deviation lower on measures of cognitive skill and are not over-represented at the high end of the distribution. The key discussion point from his paper is that "Lefties exhibit economically and statistically significant human capital deficits relative to righties, even conditional on infant health and family background."
Really? One can relate handedness to what happens to the person in the labor market? Goodman said that the physical preference for one hand over the other may create a comparative advantage or disadvantage in the labor market. Handedness may indicate differential brain structure. "If the structure of lefties' brains affects the accumulation of skills, this may be reflected in labor market outcomes and measures of productivity. Left-handed individuals might fare poorly in the labor market not due to the manual nature of left-handedness, but as a consequence of the underlying neurological wiring that leads to it." He said his paper was the first to demonstrate that lefties have consistently lower labor market earnings than right-handed individuals. "The evidence on occupational choice suggests that the primary disadvantage of left-handedness is not manual but cognitive." Goodman used five longitudinal datasets in his research and they included United States and British datasets.
Lefties born to right-handed mothers have cognitive skills roughly two-tenths of a standard deviation lower than righties. Interestingly, lefties born to left-handed mothers exhibited no statistically significant cognitive skill deficits. He said, "Intriguingly, the right-handed children of left-handed mothers exhibit cognitive gaps similar to those of left-handed children. In short, mismatch between parental and child handedness appears to be a key factor in the association between handedness and cognitive deficits. This may suggest that nurture is an important component of the handedness penalty, though other explanations cannot be ruled out."
In the US sample, male lefties' median annual earnings were $2,500 lower than those of male righties, a gap of roughly 9 percent. In the UK sample, male lefties earned £1,300 less a year than righties, a gap of roughly 5 percent. Both of these differences were statistically significant. In the US sample, female lefties earned $3,400 less than female righties, a 19 percent gap. The female UK sample was the only one not to exhibit a statistically significant earnings gap between lefties and righties, "although the regression-adjusted logarithmic specification shows a marginally significant left-handedness penalty of about 7 percent."
In his conclusion, Goodman said, "the paper leaves for future work the question of whether such gaps are caused by left-handedness or instead arise from other factors for which left-handedness is simply a proxy." He also said that "handedness is generated by neurological wiring that may affect a number of important channels relevant to labor market outcomes."
The author thanked his left-handed wife for encouraging his work "even when the coefficients troubled her."
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