Cognitive sex differences and hemispheric asymmetry: A critical review of 40 years of research

Marco Hirnstein, Kenneth Hugdahl, Markus Hausmann
2018 Laterality: Asymmetries of Body, Brain and Cognition  
article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License (, which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited, and is not altered, transformed, or built upon in any way. Additional information: Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior
more » ... ssion or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full DRO policy for further details. ABSTRACT According to a longstanding view, sex differences in cognitive abilities such as mental rotation or verbal memory arise from sex differences in hemispheric asymmetry: males are thought to be more lateralized than females which boosts their spatial but hampers their verbal skills. This idea sparked great interest and, even though it lost support in the 1990s, it is still put forward in contemporary (popular) scientific papers and textbooks. We aimed to provide a comprehensive review that summarizes the last 40 years of research. First, we confirm previous findings that the stronger hemispheric asymmetry in males is very small but robust. Second, we conclude that stronger hemispheric asymmetry, in general, does not enhance spatial and reduce verbal performance. Crucially, we carried out a systematic literature review showing that cognitive sex differences often emerge in the absence of sex differences in hemispheric asymmetry (and vice versa), implying the two phenomena are at least partly independent of each other. At present, there is insufficient data to conclude that sex differences in hemispheric asymmetry and cognitive performance are uncorrelated. However, we can conclude that sex differences in hemispheric asymmetry are certainly not the driving force behind sex differences in cognitive functioning. A meta-synthesis (i.e., a meta-analysis of meta-analyses) based on 12 million participants revealed that the male advantage in mental rotation is the second largest sex difference in the psychological literature (Zell, Krizan, & Teeter, 2015) only topped by males rating themselves more masculine than females. Other, smaller cognitive sex differences withon averagebetter female or better male performance are also well documented (for
doi:10.1080/1357650x.2018.1497044 pmid:29985109 fatcat:w6gby4lsobdpxphf53hlsgivdy