Title |
Latent variable analysis indicates that seasonal anisotropy accounts for the higher prevalence of left-handedness in men
|
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Published in |
Cortex: A Journal Devoted to the Study of the Nervous System & Behavior, May 2014
|
DOI | 10.1016/j.cortex.2014.04.011 |
Pubmed ID | |
Authors |
Ulrich S. Tran, Stefan Stieger, Martin Voracek |
Abstract |
According to the Geschwind-Galaburda theory of cerebral lateralization, high intrauterine testosterone levels delay left brain hemisphere maturation and thus promote left-handedness. Human circulating testosterone levels are higher in the male fetus and also vary with length of photoperiod. Therefore, a higher prevalence of left-handedness, coupled with seasonal anisotropy (i.e., a non-uniform distribution of handedness across birth months or seasons), may be expected among men. Prior studies yielded inconsistent evidence for seasonal anisotropy and suffered from confounding and a number of shortcomings affecting statistical power. This study examined hand preference and associations of handedness with sex, age, and season of birth in independent discovery (n = 7658) and replication (n = 5062) samples from Central Europe with latent class analysis (LCA). We found clear evidence of a surplus of left-handed men born during the period November-January, which is consistent with predictions from the Geschwind-Galaburda theory. Moreover, seasonal anisotropy fully accounted for the higher prevalence of left-handedness among men, relative to women. Implications of these findings with regard to seasonal anisotropy research and handedness assessment and classification are discussed. |
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India | 2 | 7% |
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Mendeley readers
Geographical breakdown
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Unknown | 42 | 98% |
Demographic breakdown
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Student > Master | 6 | 14% |
Student > Postgraduate | 3 | 7% |
Student > Doctoral Student | 3 | 7% |
Professor | 3 | 7% |
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Unknown | 7 | 16% |
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Unknown | 9 | 21% |