Handedness and schizotypy in a Japanese sample: an association masked by cultural effects on hand usage

Previous research has shown a robust association between schizotypy and mixed/ambiguous-handedness, but little is known about the universality of this relationship outside Western cultures. The present paper examines this issue in a sample of 413 Japanese students administered (in Japan) the Annett handedness questionnaire and a schizotypy scale (STA). Conventional analyses of current hand preference, using several indices derived from the Annett scale, mostly failed to replicate previous findings. However, there was a significant tendency for greater use of either hand in highly schizotypal males. Furthermore, a significant association between schizotypy and non-right-handedness was found—again only in males—after correcting for the effects of early switching of hand usage, presumed to be due to cultural pressure against left-handedness in Japanese society. These results were found to be highly convergent with findings previously reported for clinical schizophrenia.