Schizotypal personality and semantic functioning: Revisiting category fluency effects in a subclinical sample

Abstract

Semantic disturbances have been proposed as a possible cause of formal thought disorder in schizophrenia. Fluency tasks, in which volunteers are asked to produce as many exemplars as they can for a given category during one minute, are usually applied to the assessment of semantic processing. However, studies associating fluency and proneness to psychosis have provided conflicting results so it is not clear whether these disturbances can be identified at subclinical stages. We conducted two experiments. In the first one, 71 volunteers completed written category fluency tasks with four semantic categories (animals, fruits, clothing and vehicles). In the second experiment, 77 new participants completed oral category and phonological fluency tasks (words starting with f, t, p and c). In both experiments, we assessed schizotypal personality and vocabulary size. Schizotypal traits were not reliably associated with either productivity or originality of the responses in any experiment. In contrast, vocabulary size significantly predicted the participants' scores in all the tasks. Along with results of other recent studies, our data cast doubt on the reliability of previous observations pointing out an association between schizotypy and lexical-semantic disturbances, at least in relation to productivity and originality in fluency tests.

Semantic Search in Psychosis: Modeling Local Exploitation and Global Exploration

“…The schizotypal group produced a similar number of words and employed comparable strategies and search cues to healthy controls. Consistent with these results, other studies using standard VFT paradigms have found that psychometric schizotypy was not associated with production of fewer words 24 , 29 , 30 or lower semantic coherence of responses. 23 However, some studies have found VFT performance deficits in particular subcategories of schizotypy, such as individuals with interpersonal 51 and paranoid 52 symptom clusters.…”

“…One study found that schizotypy was associated with more atypical VFT responses, 29 whereas another study did not find this association. 30 Overall, while schizotypy shares the phenotype of odd speech (eg, metaphorical, illogical, stereotyped language) with schizophrenia, 26 standard VFT paradigms might not be sensitive to these linguistic irregularities. Evidence is accumulating that the addition of an affective or cognitive load may disproportionately impact the amount and organization of speech in individuals with schizotypal traits compared to healthy controls.…”

“…We hypothesized that, first, individuals with schizophrenia would produce fewer VFT responses than controls, 1 , 2 but that individuals with schizotypal traits would perform similarly to controls 24 , 29 , 30 given that we used a standard “animals” VFT paradigm without an affective load.…”

Semantic priming and schizotypal personality: reassessing the link between thought disorder and enhanced spreading of semantic activation

“…Crucially, in accordance with previous observations with schizophrenia patients (see Pomarol-Clotet et al, 2008 ), some authors argue that this mechanism could also underlie the presence of atypical speech patterns or ideas of reference associating unrelated events in schizotypal individuals ( Mohr et al, 2001 ; Pizzagalli, Lehmann & Brugger, 2001 ). Nevertheless, other studies have failed to obtain significant associations between the originality of fluency responses ( Hori et al, 2008 ; Rodríguez-Ferreiro & Aguilera, 2019 ) or semantic-based false memory rates ( Corlett et al, 2009 ; Kanemoto et al, 2013 ; Rodríguez-Ferreiro, Aguilera & Davies, 2020 ) and differences on schizotypal traits, so the reliability of these observations is unclear.…”

Positive Schizotypy Increases the Acceptance of Unpresented Materials in False Memory Tasks in Non-clinical Individuals

“…Atypical patterns of semantic activation in individuals with schizotypal personality have been hypothesized to underlie some of the most significant schizotypal symptoms, like thought disorder (Johnston et al, 2008), odd speech (Minor et al, 2010), delusion (Laws and Bhatt, 2005), or magical thinking (Saunders et al, 2012). Empirically, this proposal is based on previous findings associating schizotypy with semantic effects such as more original responses in semantic fluency tasks (Kiang and Kutas, 2005;Rodríguez-Ferreiro and Aguilera, 2019) or increased semantic priming (Moritz et al, 1999;Johnston et al, 2008), among others. Theoretically, this hypothesis relies on a conception of semantic memory as a network of interconnected nodes in which, when a given node is activated, semantic activation spreads to associated nodes, with stronger associates receiving higher activation levels than weaker ones (Collins and Loftus, 1975).…”