About 90% of people on Earth are right-handed, and 10% are left-handed. Three of the last six American presidents were
To find out if left-handers are smarter than right-handers,Researchers examined the differences in mathematical achievement of more than 2,300 right-handed and left-handed students between the ages of 6 and 17 in Italy. Pupils with the left dominant hand demonstrated superiority in solving more difficult problems. The results are published in Frontiers magazine.
But why can the dominant hand of a person haveanything to do with math ability? A 1995 study found that left-handers have interesting changes in brain architecture. A meta-analysis of 43 studies published in the journal Psychobiology found that left-handers have a significantly larger corpus callosum than right-handers, a bundle of nerve fibers that connects the two hemispheres of the brain.
"Perhaps a stronger connection between the twohemispheres provides better spatial perception for left-handers. It is known to be closely related to math “ability,” Giovanni Sala, an associate professor at the Institute of Integrated Medical Sciences at Fujita Health University in Japan, explains to Live Science.
However, other data show that right-handersthere is a slight intellectual advantage. In a 2017 paper published in the journal Neuroscience and Behavioral Reviews, researchers analyzed 18 other studies that included data from more than 20,400 people. Experts have found that right-handers, on average, have a slightly higher IQ than left-handers. “There is still no consensus when it comes to whether hand preference is related to intelligence and whether there is a relationship between relative agility and intelligence,” the study authors wrote. There is no clear answer to how the dominant hand affects intellectual abilities. Too many different factors influence people's cognitive and mental abilities, scientists say.
At the same time, even at the beginning of the last century, left-handerswere considered “problem” children. Thus, in J. W. Conway’s 1936 pamphlet “Prevention and Correction of Left-Handedness in Children,” left-handedness was described as a “disease” as serious and problematic as rickets and pneumonia.
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