Science in the Making: Right Hand, Left Hand. III: Estimating historical rates of left-handedness.
The BBC television programme Right Hand, Left Hand, broadcast in August 1953, used a postal questionnaire to ask viewers about their handedness. Respondents were born between 1864 and 1948, and in principle therefore the study provides information on rates of left-handedness in those born in the nineteenth century, a group for which few data are otherwise available. A total of 6,549 responses were received, with an overall rate of left-handedness of 15.2%, which is substantially above that expected for a cohort born in the nineteenth and early twentieth centuries. Left-handers are likely to respond preferentially to surveys about handedness, and the extent of over-response can be estimated in modern control data obtained from a handedness website, from the 1953 BBC data, and from Crichton-Browne's 1907 survey, in which there was also a response bias. Response bias appears to have been growing, being relatively greater in the most modern studies. In the 1953 data there is also evidence that left-handers were more common among later rather than early responders, suggesting that left-handers may have been specifically recruited into the study, perhaps by other left-handers who had responded earlier. In the present study the estimated rate of bias was used to correct the nineteenth-century BBC data, which was then combined with other available data as a mixture of two constrained Weibull functions, to obtain an overall estimate of handedness rates in the nineteenth century. The best estimates are that left-handedness was at its nadir of about 3% for those born between about 1880 and 1900. Extrapolating backwards, the rate of left-handedness in the eighteenth century was probably about 10%, with the decline beginning in about 1780, and reaching around 7% in about 1830, although inevitably there are many uncertainties in those estimates. What does seem indisputable is that rates of left-handedness fell during most of the nineteenth century, only subsequently to rise in the twentieth century.
McManus
I C
IC
UCL Department of Psychology, University College London, Gower Street, London WC1E 6BT, UK. i.mcmanus@ucl.ac.uk
Moore
James
J
Freegard
Matthew
M
Rawles
Richard
R
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015982:Bias; D002648:Child; D002675:Child, Preschool; D003142:Communication / Q000266:history; D003625:Data Collection / Q000266:history / Q000379:methods; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006225:Hand / Q000502:physiology*; D049671:History, 18th Century; D049672:History, 19th Century; D049673:History, 20th Century; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D012586:Science / Q000266:history*; D011795:Surveys and Questionnaires; D013690:Television / Q000266:history; D014956:Writing / Q000266:history; D055815:Young Adult