Visual experience affects handedness

Institute of Cognitive Neuroscience, Biopsychology, Department of Psychology, Ruhr-University of Bochum, 44780 Bochum, Germany.
Behavioural brain research (Impact Factor: 3.03). 11/2009; 207(2):447-51. DOI: 10.1016/j.bbr.2009.10.036
Source: PubMed


In birds, a lateralised visual input during early development importantly modulates morphological and functional asymmetries of vision. We tested the hypothesis that human handedness similarly results from a combination of inborn and experience-driven factors by analysing sidedness in children suffering from congenital muscular torticollis. These children display a permanently tilted asymmetric head posture to the left or to the right in combination with a contralateral rotation of face and chin, which could lead to an increased visual experience of the hand contralateral to the head-tilt. Relative to controls, torticollis-children had a higher probability of right- or left-handedness when having a head-tilt to the opposite side. No statistical significant relation between head position and direction of functional asymmetries was found for footedness and eye-preference, although the means show a non-significant trend in the same direction as was observed for handedness. Thus, an increased visual control of the hand during early childhood seems to modulate handedness and possibly other lateral preferences to a lesser extent. These findings not only show that human handedness is affected by early lateralised visual experience but also speak in favour of a combined gene-environment model for its development.

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Available from: Corinna Buerger, May 04, 2015
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    • "Those findings may be understood as suggesting that sight of the arm was functional for successfully compensating for an extrinsic load, supporting the notion that a lateral bias of vision can affect arms mobilization (see also van der Meer, van der Weel, & Lee, 1995). Data from children suffering from congenital muscular torticollis has offered supplementary information on this point (Ocklenburg et al., 2010). Those children display a permanently tilted asymmetric head posture to either side in combination with a contralateral face rotation, which favors increased visual contact with the hand contralateral to the head-tilt. "
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    • "On the other hand, although it is thought that handedness is genetically determined, a purely genetic model has yet failed to satisfactorily explain some observations regarding hand preference. Thus, when researchers apply models that attempt to interpret handedness, it is essential that factors other than genetic (e.g., environmental and cultural) are taken into account (Ocklenburg et al., 2010). For instance, experience, learning, practice (Scharoun & Bryden, 2014), early-life environment and social pressures (Suzuki & Ando, 2014) affect handedness decisively, while hand preference in people with severe visual impairments depends on a set of factors such as cultural expectations, experience, task requirements, strategy preferences, familiarity with the material, and reading habits in addition to accounting for individual differences on handedness (Sadato, 2005). "
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    • "All these findings are consistent with the emerging view that handedness is determined by multiple interacting genetic and environmental factors. A recent study [43] showed that human handedness is affected by early lateralised visual experience, thus leading the researchers to the suggestion that a combined gene-environment model could better explain the development of human handedness. Hormones also influence brain development, as has been demonstrated by comparing female and male brain lateralization and specialization [44] [45]. "
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