title: Mixed-footedness is a more relevant predictor of schizotypy than mixed-handedness.
abstract: Mixed-handedness was reported indicative of schizotypy, relevant to psychosis and schizophrenia. However, studies suffered from validity threats and did not systematically investigate associations with footedness. Moreover, there is a dearth of studies in the general population and it is currently untested whether widely used self-report scales measure schizotypy in a comparable way in student and community samples. The present study used two large and independent community and student samples (total N>2800) and utilized latent class analysis (LCA) for the classification of handedness and footedness. Psychometric properties and measurement equivalence of the Schizotypal Personality Questionnaire-Brief form (SPQ-B) in the two samples were also examined. We found that mixed-handedness (<6% prevalence), but also much more common mixed-footedness (25% prevalence), was specifically and similarly associated with higher schizotypy in both samples, Cohen d=0.15-0.18. Findings indicate that schizotypal traits in conjunction with mixed lateral preferences are thus more prevalent in the overall population than previously assumed, and that footedness may be the more relevant predictor of schizotypy than handedness. Findings are further consistent with evidence on neurodevelopmental instability, but also epigenetic mechanisms involving the sex chromosomes, regarding possible common causes of both mixed-handedness and psychosis-relevant traits.
authors.affiliation: Department of Basic Psychological Research and Research Methods, School of Psychology, University of Vienna, Vienna, Austria. Electronic address: ulrich.tran@univie.ac.at.
authors.forename: Ulrich S
authors.initials: US
authors.lastname: Tran
authors.affiliation: Department of Basic Psychological Research and Research Methods, School of Psychology, University of Vienna, Vienna, Austria; Research Methods, Assessment, and iScience, Department of Psychology, University of Konstanz, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Stieger
authors.affiliation: Department of Basic Psychological Research and Research Methods, School of Psychology, University of Vienna, Vienna, Austria.
authors.forename: Martin
authors.initials: M
authors.lastname: Voracek
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005260:Female; D007839:Functional Laterality / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D011594:Psychometrics; D012307:Risk Factors; D012569:Schizotypal Personality Disorder / Q000175:diagnosis* / Q000453:epidemiology* / Q000235:genetics; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: Exploratory structural equation modeling; Latent class analysis; Lateral preferences; Measurement equivalence