Schizotypal traits impact upon executive working memory and aspects of IQ Sandra Matheson a , Robyn Langdon b, ⁎ a Department of Psychology, Macquarie University, Sydney NSW 2109, Australia b Macquarie Centre for Cognitive Science, Macquarie University, Sydney NSW 2109, Australia Received 14 June 2006; received in revised form 15 October 2006; accepted 7 April 2007 Abstract Previous inconsistent findings concerning a link between working memory dysfunction and negative aspects of non-clinical schizotypy have been interpreted to cast doubt on the continuity model of ‘negative psychosis-proneness’. This study employed the Letter-Number-Sequencing (LNS) task and the Trail-Making Test to assess more demanding, executive working memory. A secondary concern was to rule out possible mediating effects of familial schizophrenia. It was hypothesised that executive working memory impairment would be associated primarily with negative rather than positive schizotypy even in the absence of familial schizophrenia. Matrix reasoning controlled for IQ. In 87 university-student participants with no known family history of schizophrenia, lower LNS scores were associated with higher levels of negative and positive schizotypy traits. Counter to expectations, matrix reasoning scores were also associated with schizotypy, primarily the cognitive/perceptual traits. Results were similar when participants with a known family history of schizophrenia (10) were included (N = 97). Findings support the view that impairment of executive working memory (indexed by LNS) is a reliable cognitive marker for negative (and perhaps also positive) schizophrenia vulnerability, independent of familial schizophrenia, and provide the first indication that some facets of IQ (e.g. inductive reasoning) might also be compromised in non-clinical schizotypy. © 2007 Elsevier Ireland Ltd. All rights reserved. Keywords: Risk factors for schizophrenia; Cognitive markers for schizophrenia; Inductive reasoning; Psychosis-proneness 1. Introduction On a dimensional view of schizophrenia, clinical schi- zophrenic symptoms lie at the extreme end of a continuum which ranges in severity from a mild, non-clinical form of schizotypy to the actual clinical disorder (Meehl, 1989). Consistent with this view, the three clinical syndromes of schizophrenia: ‘positive’ reality distortion, ‘negative’ withdrawal and ‘disorganised’ speech and behaviour (Liddle, 1987), are mirrored in the three non-clinical schizotypy factors of ‘cognitive/perceptual’ (positive), ‘interpersonal’ (negative) and ‘disorganised’ traits respec- tively (Raine, 1986; Suhr and Spitznagel, 2001a). The possibility that these three schizotypal dimensions might reflect independent sites of neuropathy of ranging severity has also been raised. The clinical negative syndrome, in particular, has been associated with frontal abnormalities, while the positive syndrome has been associated with temporal lobe abnormalities (Crow, 1980; Liddle, 1987). In accord with this view, schizophrenia patients with marked negative symptoms show performance deficits on tasks that tap frontal lobe compromise, in particular wor- king memory tasks (Barch, 2003); when positive Available online at www.sciencedirect.com Psychiatry Research 159 (2008) 207 – 214 www.elsevier.com/locate/psychres ⁎ Corresponding author. Macquarie Centre for Cognitive Science, Macquarie University, Sydney NSW 2109, Australia. Tel.: +61 2 9850 6733; fax: +61 2 9850 6059. E-mail address: robyn@maccs.mq.edu.au (R. Langdon). 0165-1781/$ - see front matter © 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.psychres.2007.04.006