Investigating the relationships between verbal fluency, processing speed and demographic variables in a multilingual South African Sample

Abstract

This study examined the association between phonemic and semantic verbal fluency as measured by the Controlled Oral Association Test (COWAT-FAS and animals) test, and demographic variables (age, years of education, language experiences, and socioeconomic status) and further the moderating effect of processing speed measured by the Symbol Digit Modality Test (SDMT) on the relationship between verbal fluency performance and demographic variables. The study comprised a sample of 97 healthy adults between 20 to 60 years from diverse educational backgrounds with multiple language experiences. Pearson’s correlation revealed a significant positive associations between the COWAT F trial and SDMT (r = 0.302; p < 0.01) and COWAT A trial SDMT (r = 0.633; p < 0.0001). A moderate positive association was found between SDMT (r = 0.424; p < 0.0001) on COWAT S trial. A negative association was observed between the COWAT Animals trial and SDMT Oral and Written scores. The results showed that when processing speed was introduced as a moderator, years of education and English as a first language in the COWAT F trial were not significant. Processing speed moderated the association of Years of education, number of languages, and English as a first language on the COWAT A trial. The findings highlight that demographic variables contribute to verbal fluency performance. However, processing speed plays a dominant role in the performance outcome, changes in verbal fluency due to aging and low education may be linked to reductions in cognitive efficiency.