Sources of between-subjects variability in perceptual asymmetries: a meta-analytic review

A number of studies have reported correlations between subjects' asymmetry scores on left and right hemisphere specialized tasks. In this paper we report the results of meta-analyses performed on these correlations. Results showed positive correlations between subjects' asymmetry scores on left and right hemisphere specialized tasks in both modalities (asymmetry scores were computed as R-L for both left and right hemisphere specialized tasks). Thus, in both modalities, some of the between-subjects variability in asymmetry scores appears to reflect non-stimulus specific individual differences in perceptual asymmetry. For the visual asymmetry tasks, results also showed that the subjects' asymmetry scores on left and right hemisphere specialized tasks were more highly correlated under conditions of bilateral than unilateral input. This finding suggests that bilateral tasks may be more sensitive to "characteristic perceptual asymmetry" than unilateral tasks.