Frogs, apples, and sand: effects of cognitive and demographic factors on letter fluency performance

The current study investigated the contributions of working memory, vocabulary size, education and age to letter fluency performance in healthy adults (N = 50, mean age = 26.5). We administered a letter fluency task using three stimulus letters (F, A, S). Using Bayesian generalized linear mixed model analysis, we established independent contributions of each predictor to letter fluency performance. While our results demonstrate that age, vocabulary size, education level and, to a lesser extent, working memory capacity contribute to performance on the letter fluency task, they also indicate a complex interplay of these factors. The results highlight the importance of separately assessing various verbal and executive skills in combination with demographic factors when using fluency tasks as indicators of adults’ general verbal skill.