Fig. 4.

Handedness differentially affects asymmetry across distinct brain systems. Mean laterality estimates for each of the 4 factors in Fig. 3 are plotted for independent data samples of right-handed (n = 38) and left-handed (n = 38) individuals. (A) A significant interaction between hand dominance and factor is observed (P < 0.005) with an effect of handedness observed for factor 3 (***, P < 0.001). Bars represent standard error of the mean. (B) The laterality index distribution for factor 2 is plotted split by handedness. Though the distributions overlap, there are 2 left-handed individuals with complete reversal of asymmetry. (C) The distributions for factor 3 show a marked effect of handedness with right-handed individuals demonstrating greater asymmetry.