ORIGINAL ARTICLE Is Semantic Processing Impaired in Individuals With High Schizotypy? Celia J. A. Morgan, BSc, PhD,*† Nick J. Bedford, BSc,* Alison O’Regan, BA, PGradDip,‡ and Susan L. Rossell, BSc, PhD*‡ Abstract: Semantic processing deficits are present in schizophrenia. How- ever, this research has often been criticized for methodological artifacts and confounds, including long hospitalizations and medication of patient sam- ples. Utilizing high schizotypes (psychosis-prone individuals) can overcome these confounds. Previously, similar deficits have been reported in high schizotypes and schizophrenia on semantic priming tasks. In contrast to schizophrenia research, no other types of semantic processing have been examining in high schizotypes. Semantic processing is multifaceted, thus, deficits on semantic priming can not answer whether high schizotypes have difficulty with explicit semantic processing, that is, on tasks that require the conscious recollection of semantic information. In the current study, 24 high and 30 low scorers on the O-LIFE schizotypy scale were administered a battery of semantic processing measures. The high schizotypy group did not show global semantic processing impairments (as has been shown in schizo- phrenia), only impairments on a task designed to examine subtle categori- zation processing. Such deficits can be equated to those found on semantic priming tasks, in that both require quick and accurate access to semantic networks. Key Words: Schizotypy, semantic memory, categorization. (J Nerv Ment Dis 2009;197: 232–238) R esearch on schizotypy or “psychosis-proneness” has suggested that the symptoms of schizophrenia are at the extreme end of a continuum that ranges from healthy, through to florid psychosis (Claridge and Hewitt, 1987). Individuals with high schizotypy are considered part of the normal diversity but are argued to mark a cognitive vulnerability towards psychosis, with these individuals performing many cognitive tasks similarly to individuals with schizophrenia (Peters et al., 1994). Hence, schizotypy has been associated with deficits in attention on the Continuous Performance Task (CPT; Lenzenweger et al., 1991; Obiols et al., 1992) and executive functioning, in the form of perseverative errors on the Wisconsin Card Sorting Task (Gooding et al., 1999; 2001; Tallent and Gooding, 1999; Suhr, 1997). In the last few years, semantic processing deficits have been suggested to be central to cognitive abnormalities in schizophrenia and are present on a wide range of tasks (Chen et al., 1994; Tamlyn et al., 1992; Rossell et al., 1998, 1999, 2000). Despite this, only a few studies have examined the relationship between semantic pro- cessing and high schizotypy. Thus far, the majority of these studies have used a semantic priming task. This is an experimental tech- nique that examines the nature and the relationship between the mental representations of words. It does so implicitly, that is, without being consciously directed to the precise rationale for the task (thus is not conscious), such that, when asked to engage in either naming or lexical decision semantic priming task, healthy controls illustrate a facilitated response for related or associated word pairs compared with unrelated word pairs. Previous experience with the related information is postulated to be the reason behind the facilitated “priming effect.” Semantic priming differences in partic- ipants with high schizotypy ratings have now been established in several studies (Beech et al., 1991; Kravetz et al., 1998; Moritz et al., 1999; Morgan et al., 2006). On the basis of these findings, it has been argued that semantic deficits in high schizotypes are similar to those reported in schizophrenia. There has been little research, however, on other aspects of semantic memory in schizotypy. Deficits in verbal fluency have been reported (Barrantes-Vidal et al., 2003; Duchene et al., 1998). Bar- rantes-Vidal reported an association between positive symptoms in schizotypy (i.e., unusual experiences on the Oxford-Liverpool In- ventory of Feelings and the Experiences O-LIFE scale) and in- creased verbal fluency. While, Duchene demonstrated that high schizotypy scorers produced more rare words during fluency than low schizotypy scorers (similar results were also reported by Miller and Chapman 1983 on a word association task). However, both these studies used the letter version of verbal fluency, where partic- ipants are required to generate as many words as they can that begin with the same letter. This task requires participants to access their lexicon and then hold and maintain previously generated words on line. As such, this task probably indexes executive functioning rather than semantic memory per se. Category fluency can be viewed as a more appropriate semantic memory task, and while deficits on this task have been observed in unaffected siblings of people with schizophrenia (Laurent et al., 1999) and people with schizotypal personality disorder (Trestman et al., 1995), it has not thus far been administered to healthy individuals scoring high on schizotypy. Kiang and Kutas (2005) report the only other study of semantic processing in high and low schizotypy participants. They assessed responses to a category-verification task and found no behavioral group differences. Thus, while considerable effort has been devoted to examining executive functioning and performance on semantic priming tasks in this psychosis-prone population, as yet, there has been no study that has fully characterized the semantic processing performance of high schizotypy individuals on a comprehensive semantic battery of explicit memory measures. Explicit semantic functions are those that require conscious recollection of semantic attributes, such as naming everyday objects, understanding mean- ings of words, or understanding meaning of sentences. Therefore, this study set out to fully characterize the explicit semantic processing performance of individuals scoring highly on schizotypy scales. We chose to take extreme scorers on the STA (an *Section of Cognitive Neuropsychiatry, Psychological Medicine, Institute of Psychiatry, De Crespigny Park, London, United Kingdom; †Clinical Psycho- pharmacology Unit, University College London, London, United Kingdom; and ‡Cognitive Neuropsychiatry Laboratory, Alfred Psychiatry Research Centre, School of Psychology, Psychiatry, and Psychological Medicine, Monash University, Melbourne, Australia. Supported by British Academy to a small project. Send reprint requests to Susan L. Rossell, BSc, PhD, Cognitive Neuropsychiatry Laboratory, Alfred Psychiatry Research Centre, School of Psychology, Psy- chiatry and Psychological Medicine, Monash University, 1st Floor, Old Baker Building, The Alfred Hospital, Commercial Road, Melbourne VIC 3004, Australia. E-mail: susan.rossell@med.monash.edu.au. Copyright © 2009 by Lippincott Williams & Wilkins ISSN: 0022-3018/09/19704-0232 DOI: 10.1097/NMD.0b013e31819dc127 232 | www.jonmd.com The Journal of Nervous and Mental Disease • Volume 197, Number 4, April 2009