Schizotypy is increased in mixed-handers, especially right-handed writers who use the left hand for primary actions

Associations between schizotypy and handedness were examined in 733 undergraduates for the Sta and Unex scales of the O-LIFE inventory and several measures derived from the Annett hand preference questionnaire. Higher schizotypy scores were found for mixed-handers defined in various ways, including inconsistent preference for any item of the questionnaire and also the presence of either hand responses. There was a marked elevation of schizotypy scores (p < .001) for right-handed writers who prefer the left hand for other ‘primary’ actions (throwing, racket, match, hammer, toothbrush and scissors). This observation was replicated in 182 students assessed on the Rust Scale of Schizotypal Cognitions. Several findings agree that inconsistent hand preference is associated with a raised probability of schizotypal thinking.