Analysis of sociodemographic and linguistic influences on verbal fluency performance in Basque and Catalan bilingual adults

The aim of the study was to generate norms for letter, semantic, and verb fluency tests for Basque and Catalan speakers from Spain. The sample consisted of 275 bilinguals aged between 18 and 85 years who completed the tests for each language (Basque–Spanish or Catalan–Spanish) with order counterbalanced. The influence of predictors was evaluated with Generalized Linear Mixed Models. Language by letter and type of language by semantic category interactions were found, where people scored higher in letter fluency when tested in Spanish than in Basque or Catalan, and produced more words in the “animals” category compared to “fruits” and “occupations". Production increased in all tests with higher education. Letter and semantic fluency scores increased until ages 40–45, after which they decreased, except for action fluency, where Basque speakers had decreased scores with age. Basque men scored higher than Basque women in letter and semantic fluency, but lower in verb fluency; while Catalan women scored higher than Catalan men in semantic and verb fluency, but lower in letter fluency. The study provides, for the first time, verbal fluency norms for Basque and enriches norms availability for Catalan. Socio-psycholinguistics aspects may have an impact on performance.