I do it with my left! It is well known that many people do not belong to the majority of right-handed people. But how many are there actually and are two-handed use also widespread? The largest study on the topic to date shows that the left-handed rate is 10.6 percent, but almost ten percent of people seem to be able to handle equally well on both sides.
With which hand do you operate the computer mouse, smartphone or hold the coffee cup? It is well known that most of them do such activities with the right, because this is typical for humans and distinguishes us from our closest relatives in the animal kingdom. Why this is so, and why there are quite a few exceptions, is still unclear. But how many people are actually left-handed? A team of researchers from the Universities of St. Andrews, Athens, Oxford, Bristol and Bochum investigated this with a so-called meta-study: They evaluated various studies based on data from around 2.4 million participants whose handedness had been examined in various activities .
The result: “The best estimate is a total of 10.6 percent left-handedness,” reports co-author Sebastian Ocklenburg from the Ruhr University in Bochum. Obviously, one has to differentiate: “How common left and right-handed people are in each case depends on how strict the criteria are that the authors apply,” explains Ocklenburg. When using the strictest criteria, only 9.34 percent of people are left-handed. Using less stringent criteria, 18.1 percent are not right-handed, as the researchers put it.
Ambidextrous
Usually handedness is made dependent on which hand someone writes with. In the current study, however, the research team took into account the fact that around nine percent of people use different hands for different tasks. That made for more accurate results. “The proportion of people who use different hands for different tasks is, according to the data, almost as large as the proportion of people who are left-handed,” says co-author Silvia Paracchini of the University of St. Andrews.
As the researchers point out, there is still a need to investigate the distribution of handedness and its backgrounds. For example, it is unclear to what extent the development of two-handedness is shaped by cultural factors. Insights into the topic could also contribute to an understanding of evolution. The question arises why, in contrast to monkeys, humans have developed a tendency to right-handedness.
Source: Article: Ruhr University Bochum, Article: Psychological Bulletin, doi: 10.1037 / bul0000229