Sex differences in dichotic listening

The present study quantified the magnitude of sex differences in perceptual asymmetries as measured with dichotic listening. This was achieved by means of a meta-analysis of the literature dating back from the initial use of dichotic listening as a measure of laterality. The meta-analysis included 249 effect sizes pertaining to sex differences and 246 effect sizes for the main effect of laterality. The results showed small and homogeneous sex differences in laterality in favor of men (d = 0.054). The main effect of laterality was of medium magnitude (d = 0.609) but it was heterogeneous. Homogeneity for the main effect of laterality was achieved through partitioning as a function of task, demonstrating larger asymmetries for verbal (d = 0.65) than for non-verbal tasks (d = 0.45). The results are discussed with reference to top-down and bottom-up factors in dichotic listening. The possible influence of a publication bias is also discussed.