| dc.description.abstract | Interindividual differences in neural anatomy have typically been linked to functional lateralization. For instance, the role of anatomical connectivity in supporting or establishing functional hemispheric specialisation, has been supported by evidence for correlations between handedness and callosal morphology. After publishing a number of influential post-mortem studies in the late 1980s, Sandra Witelson reinforced the notion that the corpus callosum of left-handers is larger than that of right-handers. However, critiques towards the validity and reliability of the Witelson studies, and the varied success of attempted replications of the findings, has led researchers to question the true relationship between handedness and callosal morphology. Hence, the primary aim of the present study is to conceptually replicate the findings of Witelson, by repeating the study with a larger sample (N > 1000), utilizing a dataset of callosal measures from structural MRI borrowed from the Human Connectome Project (preregistration DOI: https://doi.org/10.17605/OSF.IO/3WS5C). The findings of the present study argue against the assumptions made by Witelson. The analyses of the midsagittal callosal surface area demonstrated no significant main effect of the different hand groups on total corpus callosum size, whilst controlling for sex and handedness, assessed using different criteria. Likewise, for analyses of the often-indicated isthmus subsection, the findings revealed no significant main effect of handedness, or any moderator effects of sex. These findings indicate that previous statements regarding the relationship between handedness and corpus callosum morphology should be considered imprecise. | eng |