Speech as a graph: developmental perspectives on the organization of spoken language.

Language has been taken as a privileged window to investigate mental processes. More recently, descriptions of psychopathological symptoms have been analyzed with the help of natural language processing tools. An example is the study of speech organization using graph theoretical approaches that began around ten years ago. After its application in different areas, there is a need to characterize better what aspects can be associated with typical and atypical behavior throughout the lifespan, given variables related to aging, as well as biological and social contexts. The precise quantification of mental processes assessed through language may allow us to disentangle bio/social markers by looking at naturalistic protocols in different contexts. In the current review, we discuss ten years of studies in which word recurrence graphs were adopted to characterize the chain of thoughts expressed by individuals while producing discourse. Initially developed to understand formal thought disorder in the context of psychotic syndromes, this line of research has been expanded to understand atypical development in different stages of psychosis, differential diagnosis (such as dementia), as well as typical development of thought organization in school-age children/teenagers in naturalistic and school-based protocols. We comment on the effects of environmental factors, such as education and reading habits (in monolingual and bilingual contexts), in clinical and non-clinical populations at different developmental stages (from childhood to aging). Looking towards the future, there is an opportunity to employ word recurrence graphs to address complex questions that consider bio/social factors within a developmental perspective in typical and atypical contexts.