Tran Ulrich S, Stieger Stefan, Voracek Martin
University of Vienna, School of Psychology, Vienna, Austria.
University of Vienna, School of Psychology, Vienna, Austria; Research Methods, Assessment, and iScience, Department of Psychology, University of Konstanz, Germany.
Cortex. 2014 Aug;57:188-97. doi: 10.1016/j.cortex.2014.04.011. Epub 2014 May 9.
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.
根据大脑半球偏侧化的 Geschwind-Galaburda 理论，子宫内睾酮水平高会延迟左脑半球成熟，从而促进左利手。男性胎儿的循环睾酮水平较高，且会随光照周期长度变化。因此，男性中左利手的患病率可能更高，同时还会出现季节性不对称现象（即不同出生月份或季节的利手分布不均匀）。先前的研究对于季节性不对称现象的证据并不一致，并且存在混杂因素以及一些影响统计效力的缺点。本研究采用潜在类别分析（LCA），在来自中欧的独立发现样本（n = 7658）和重复样本（n = 5062）中，研究了利手偏好以及利手与性别、年龄和出生季节的关联。我们发现了明确的证据，即 11 月至 1 月期间出生的左利手男性过剩，这与 Geschwind-Galaburda 理论的预测一致。此外，季节性不对称现象完全解释了男性相对于女性左利手患病率更高的原因。本文讨论了这些发现对季节性不对称研究以及利手评估和分类的意义。
