Differences between two studies of hand preference in psychiatric patients.

Significant differences in handedness patterns between groups of psychiatric patients and normal controls were identified in two recent British studies, with substantial disagreement in some important findings. Most of the discrepancies were attributable to the different application of a simple classification of handedness data, and the remainder to differences in sample size. Diagnosis, sex and age were then found to have a similar effect on handedness in both studies. Neurotic patients were similar to controls regardless of classification, whereas mixed handedness in personality disorder depended on it. There was no overall excess of left-handedness among schizophrenics, but trends towards excess sinistrality in men and fully dextrality in women approached significance.