Try this: list as many words as you can that start with the letter F in the next 60 seconds …

The cognitive processes that underpin letter fluency

In the letter (or phonemic) fluency task you are asked to generate words beginning with a specific letter (e.g. "F", "A", "S"), within a given time frame (usually 1 min).

The task is thought to rely on language processes, such as lexical retrieval and word knowledge. In addition, it should activate executive processes, such as task goal maintenance and the ability to avoid repeated responses.

The letter fluency task has been used extensively in language research and neuropsychological practice but the nature of the mechanism underlying performance in this task remains unclear.

Disentangling the contributors to letter fluency

We 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 generalised 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.

Our 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.