The influence of schizotypal personality on measures of executive function in healthy individuals

Background: A growing body of research (e.g. Park and Holzman, 1992) suggests that both schizophrenic patients and healthy participants with high scores on schizotypal personality traits (e.g. Peters et al., 1994) show reduced executive functioning. The current research examined the relationships between three aspects of schizotypal personality (positive, negative and disorganised) and performance on a battery of executive tasks assessing attention, working memory, verbal fluency and verbalisable rule learning and reversal. Methods: Eighty-five healthy participants completed the Schizotypal Personality Questionnaire (SPQ, Raine, 1991) and completed five executive tasks. Results: Multiple regression analyses revealed no significant relationships between schizotypal personality and four of the five executive measures. However, high scores on the Odd Beliefs and Magical Thinking subscale of the SPQ positive factor significantly predicted fewer correct responses in the rule reversal phase of a categorisation task. Thus, executive disruption was particularly reflected in a pattern of perseverative behaviour. However, the lack of significant associations between schizotypal personality and the other traditional executive measures may have been obscured by the regression procedure, in which power is reduced by multicollinearity. Therefore, the findings will be compared with a more powerful analysis based on the novel statistical technique, partial least squares (PLS, Nestor et al., 2002)