The distribution of hand preference in normal men and women

The distributions of the hand preferences (Geschwind scores) were studied in men and women. The incidences of the right-, mixed-, and left-handers were 66.1, 30.5, and 3.4%, respectively. The left- and right-handers (LHs, RHs) were represented by two bars located at the opposite ends of a J-shaped histogram for the total sample, men, and women. The distributions for the total RHs, and male RHs were not J-shaped, but negatively skewed, the mode being close to the mean. The frequencies for the females increased linearly. The distributions for the LHs did not significantly deviate from normality. Except for the LHs, the percentage distributions of the Geschwind scores were J-shaped. The LHs were evenly distributed by chance to be expected in a random sample from a rectangular population. The incidence of weak right-handedness was significantly higher in men than women. The total RHs were more lateralized than the total LHs who showed a tendency toward weak left-handedness. In males, the incidence for weak left-handedness was significantly higher than that for strong left-handedness. The opposite was established for females. The probability of the consistent right-handedness was significantly higher in women than men. The LHs were less lateralized, and more widely dispersed than the RHs. The statistical analysis of the distributions indicated that females tended to be more lateralized, i.e., more right-handed, and more left-handed, than males.