What is it about?
From Leonardo da Vinci to Oprah Winfrey, and from Napoleon Bonaparte to Jimi Hendrix, the talents of left-handers have been celebrated across the generations. However, the prevalence of people who favour their left hand over their right has always been a rough estimate – until now. In the biggest ever global study of handedness researchers from across Europe, led in by the National and Kapodistrian University of Athens, have concluded that 10.6% of the world’s population are left-handed. The study, a meta-analysis totaling more than 2 million people was conducted by researchers at the National and Kapodistrian University of Athens, University of Oxford, University of Bristol, Ruhr University Bochum, and St Andrews and published in the Psychological Bulletin. Specifically, researchers examined five meta-analyses involving 200 studies totaling 2,396,170 individuals on hand preference for different manual tasks. They showed that left-handedness prevalence lies between 9.34% using the most stringent criterion of left-handedness, to 18.1% using the most lenient criterion of non-right-handedness, with the best overall estimate being 10.6%. Typically handedness is measured by which hand is used to write with. However, for this study researchers allowed for the fact that about 9% of people use different hands for different tasks which further improved the accuracy for their findings.
Photo by Cathryn Lavery on Unsplash
Why is it important?
Frequency of left-handedness has shaped and underpinned different fields of research, from cognitive neuroscience to human evolution. While hundreds of empirical studies have assessed handedness, there has never been a large-scale, comprehensive review of the prevalence of handedness and the factors that moderate it. Understanding handedness moreover contributes to our understanding of human evolution. For example, it has been claimed that right-handedness, along with the capacity to make and use tools, to use language, and to show functional and anatomical cerebral specialisation, are characteristics specific to humans, and that they are intimately tied together in the divergent evolution of man from apes.
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This page is a summary of: Human handedness: A meta-analysis., Psychological Bulletin, June 2020, American Psychological Association (APA), DOI: 10.1037/bul0000229.
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