Lateral preference and schizotypy revisited: comparison of handedness measurement and classification methods

A sample of 256 undergraduate students was administered five schizotypy scales and a lateral preference questionnaire consisting of 41 handedness items, in order to examine the effect of different approaches to the measurement and classification of handedness on the relationship between schizotypy and lateral preference. The extended handedness questionnaire included the 12 items of Annett's handedness questionnaire, the 10 items of Oldfield's (1971) Edinburgh Handedness Inventory, the 19 items of the lateral preference questionnaire used by Kelley and Coursey (1992a), and additional items from Steenhuis and Bryden's (1989) 32-item Waterloo Handedness Inventory, allowing the examination and comparison of a variety of handedness classification schemes and the computation of several continuous measures of handedness, and comparison of their relationships to schizotypy. Different approaches to the measurement and classification of handedness yielded somewhat different findings concerning the relationship to schizotypy, which also varied depending on gender and the schizotypy measure involved. Among males, higher schizotypy scores were associated with more dextral lateral preference, whereas among females higher schizotypy was associated with mixed right-handedness.