Is there a sex difference in human laterality? IV. An exhaustive survey of dual-task interference studies from six neuropsychology journals.

The entire contents of six neuropsychology journals (161 volumes, 612 issues) were screened to identify dual-task laterality experiments. Of 112 experiments thus identified, 45.5% provided information about sex differences. Although 23 experiments yielded at least one significant main effect or interaction involving the sex factor, only 5 outcomes represented an unambiguous sex difference in laterality. All 5 of those sex differences support the hypothesis of greater hemispheric specialization in males. The confirmatory outcomes constitute less than 10% of the informative experiments and less than 5% of the total population of experiments. These data alone do not rule out the possibility that sex differences are chance findings (Type I errors). However, when considered along with similar results from perceptual laterality data previously examined, the dual-task data fit the pattern of a small but reliable population-level sex difference in human laterality.