Right-handers have negligibly higher IQ scores than left-handers: Systematic review and meta-analyses

Neurosci Biobehav Rev. 2018 Jan;84:376-393. doi: 10.1016/j.neubiorev.2017.08.007. Epub 2017 Aug 19.

Abstract

The relationship between intelligence and handedness remains a matter of debate. The present study is a systematic review of 36 studies (totaling 66,108 individuals), which have measured full IQ scores in different handedness groups. Eighteen of those studies were further included in three sets of meta-analyses (totaling 20,442 individuals), which investigated differences in standardized mean IQ scores in (i) left-handers, (ii) non-right-handers, and (iii) mixed-handers compared to right-handers. The bulk of the studies included in the systematic review reported no differences in IQ scores between left- and right-handers. In the meta-analyses, statistically significant differences in mean IQ scores were detected between right-handers and left-handers, but were marginal in magnitude (d=-0.07); the data sets were found to be homogeneous. Significance was lost when the largest study was excluded. No differences in mean IQ scores were found between right-handers and non-right-handers as well as between right-handers and mixed-handers. No sex differences were found. Overall, the intelligence differences between handedness groups in the general population are negligible.

Keywords: Cerebral laterality; Cognitive ability; Hand preference; Handedness; IQ; Intelligence.

Publication types

  • Meta-Analysis
  • Review
  • Systematic Review

MeSH terms

  • Functional Laterality*
  • Humans
  • Intelligence Tests / statistics & numerical data*