The association between discourse production and schizotypal traits

Discourse abnormalities are a prominent feature in schizophrenia spectrum disorders, including poor lexical diversity, and have been found to differentiate patients from healthy subjects. Several theories explaining the causes of this exist, including, but not limited to, perseveration and top-down and bottom-up processes. However, the role of schizotypal personality traits in semantic functioning is often overshadowed by research on explicitly clinical psychotic symptoms. In the present study, we examined schizotypal traits at a non-clinical threshold and their association with lexical diversity and discourse cohesion using two automated Natural Language Processing (NLP) tools. 300 college students completed the Schizotypal Personality Questionnaire- Brief Revised (SPQ-BR) and recorded a speech sample describing a detailed painting. We assessed lexical diversity using two Type-Token-Ratio (TTR) measures from the Tool for the Automatic Analysis of Lexical Diversity (TAALED) and discourse cohesion using sentence-level average cosign similarity (ACS) with FastText. We found that high schizotypal traits (ST), specifically positive traits, were associated with low lexical diversity and high discourse cohesion. Our findings suggest that even when clinically significant schizophrenia (SZ) symptoms are not present, discourse abnormalities are present in healthy populations with high ST below a clinical threshold. The stronger association with positive traits suggests that theories of perseveration and bottom-up processing may warrant further investigation in schizophrenia-spectrum disorders.