Schizotypy and handedness in Japanese participants, revisited

Although previous studies have suggested a relationship between mixed-handedness and schizotypic symptoms, possibly indicating a predisposition to schizophrenia, the participants involved were exclusively from Western cultures. Only two reports have examined the relationship between handedness and schizotypy in Asian cultures, and both of these studies failed to show a significant association between mixed-handedness and schizotypy, possibly due to cultural pressures against left-handedness. In the present study we examined the relationship between handedness and schizotypy among Japanese participants (N=231, study 1; N=274, study 2). In order to avoid cultural biases, we used a modified handedness scale in addition to the traditional scale developed in Western cultures. As a result, we show for the first time that mixed-handed Japanese participants have the strongest schizotypal traits, particularly positive schizotypic traits (p<.05). These results suggest that positive schizotypal traits may be universally associated with mixed-handedness or atypical cerebral lateralisation, even in non-Western cultures.