Sex Differences in Left-Handedness: A Meta-Analysis of 144 Studies

Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom.
Psychological Bulletin (Impact Factor: 14.76). 10/2008; 134(5):677-99. DOI: 10.1037/a0012814
Source: PubMed


Human handedness, a marker for language lateralization in the brain, continues to attract great research interest. A widely reported but not universal finding is a greater male tendency toward left-handedness. Here the authors present a meta-analysis of k = 144 studies, totaling N = 1,787,629 participants, the results of which demonstrate that the sex difference is both significant and robust. The overall best estimate for the male to female odds ratio was 1.23 (95% confidence interval = 1.19, 1.27). The widespread observation of this sex difference is consistent with it being related to innate characteristics of sexual differentiation, and its observed magnitude places an important constraint on current theories of handedness. In addition, the size of the sex difference was significantly moderated by the way in which handedness was assessed (by writing hand or by other means), the location of testing, and the year of publication of the study, implicating additional influences on its development.

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Available from: Marietta Papadatou-Pastou
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    • "Furthermore, we found evidence that a bimanual task which involves the risk of hurting oneself, if executed faultily (using a hammer to drive a nail into something), had the highest reliability of classifying handedness on its own. Bimanual tasks are assumed to confer a higher classification reliability (Papadatou Pastou et al., 2008). However, our study suggests that it may need to be a task which requires accuracy and, if executed faultily, exerts a direct negative or hurtful consequence to the individual performing it. "
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    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. 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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    • "Approximately 90% of humans are right-handed, with the rest made up of left-handed and ambidextrous individuals. It is well established as to singletons that the prevalence of left-handedness in males is slightly higher than that in females (Papadatou-Pastou et al., 2008). There has been a long-standing debate on the complex correlation between the development of human hand preference and brain lateralization. "
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    ABSTRACT: There has been a long-standing debate on the complex correlation between the development of human hand preference and brain lateralization. Handedness, used as a proxy for cerebral lateralization, is a topic of considerable importance because of its potential to reveal the mechanisms of the underlying pathophysiology of problems related to brain development or cognitive systems. Twin studies, which represent an important method of research in human genetics, would provide valuable suggestions to the studies on the relationship between lateralization and cognitive systems. Many studies have been performed using twin subjects; however, the results are inconsistent, partly because of sample size, background assumptions, data limits or inaccuracies, incorrect zygosity classification, and/or lack of birth histories. In summary, within the long history and large number of twin studies performed on handedness, a surprisingly large number of controversial findings have been reported, suggesting the complicated nature of this phenotype. In this mini review, the wide variety of twin studies on human handedness performed to date are introduced.
    Full-text · Article · Jan 2014 · Frontiers in Psychology
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    • "Humans exhibit sidedness preferences when performing many routine tasks (see Damerose and Vauclair 2002; Lalumière et al. 2000; Papadatou-Pastou et al. 2008). In most cases, limbs and digits on the right side are utilized more than those on the left (Carey et al. 2001; "
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    ABSTRACT: Studies have repeatedly documented that 60 to 80 % of adults cradle (or carry) infants on the left side of their bodies. However, very little is known about sidedness tendencies when carrying objects in general. The present naturalistic study examines sidedness among college students as they carried books and other “academic” objects on campus. Special attention was given to sidedness biases in the use of a cradling-like carrying style. Over 2,500 observations were made of non-infant object carrying by college students in Malaysia and the United States. In both countries, females used a cradling-like carrying style much more than did males, while males predominantly carried books beside the hip. Regarding sidedness, there were significant left sided biases in the use of a cradling-like style by females in both countries and by males in Malaysia. Other sidedness differences in object carrying were also found. The left sided bias in infant carrying documented in other studies roughly resembles what this study found regarding the carrying of objects bearing no resemblance to infants, especially by females. Theories for left sided biases in infant cradling need to account for why similar biases exist particularly among females when they are carrying inanimate objects.
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