Word Fluency Test

Background

The Letter Fluency Test is a neuropsychological assessment tool of speech production. Specifically, it measures a person's ability to generate words based on a specific phonetic prompt such as the letters A, F, or S within a certain time span.

Arthur Benton and colleagues are credited with developing the modern version of the Letter Fluency Task as an oral, clinical assessment tool in the 1960s. They later renamed the task as the Controlled Oral Word Association Test (COWAT) when including it in the Multilingual Aphasia Examination.

The Inquisit implementation runs the Letter Fluency Task as a written task and requires people to type as many words beginning with the letters A,F,S within 2 minutes. Participants are instructed that proper nouns such as names as well as plural words do not count as words. The program provides a preliminary word count based on the entered responses but requires a manual check of the actual words entered.

Alternatively, the test can be run with voice recording. Sound files are saved for each letter for additional analyses.

Task Procedure

Participants work on three trials, one for each of the following letters: A, F, S. The presentation order of the letters is randomly determined. Participants have 2 minutes to enter as many words as they can into the provided textbox. A warning is given 1s before the end of the trial.

What it Measures

The Letter Fluency Test is a measure of speech production capacity

Psychological domains

• Strategic Search: The brain must develop a search strategy that bypasses typical semantic connections (like "cat-dog") to find phonetically related words.
• Working Memory: To keep track of the letters and words already mentioned.
• Cognitive Flexibility: The ability to switch between different "clusters" of words (e.g., moving from "fish" and "fin" to "frog").
• Inhibition: Suppressing incorrect responses, such as words starting with the wrong letter or forbidden proper nouns.

Main Performance Metrics

• Estimated Word Count: Total number of estimated words produced for the three target letters

Psychiatric Conditions

Speech Production is particularly affected by the following conditions:

• Alzheimer's Disease & Dementia
• Schizophrenia
• Primary Progressive Aphasia (PPA)
• Stroke
• Traumatic Brain Injury (TBI)
• Huntington’s Disease

Test Variations

References

Search Google Scholar for peer-reviewed, published research using the Inquisit Word Fluency Test.

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Anderson, N. (1965). Word associations to individual letters. Journal of Verbal Learning and Verbal Behavior, 4(6), 541-545.

Borkowski, John G., Benton, Arthur L., & Spreen, Otfried. (1967). Word fluency and brain damage. Neuropsychologia, 5(2), 135-140.

Ross, T. (2003). The reliability of cluster and switch scores for the Controlled Oral Word Association Test. Archives Of Clinical Neuropsychology, 18(2), 153-164.

Rodriguez-Aranda, C., & Martinussen, M. (2006). Age-related differences in performance of phonemic verbal fluency measured by Controlled Oral Word Association Task (COWAT): A meta-analytic study. Developmental Neuropsychology, 30(2), 697-717.

Holcomb, M., Kimball, T., Luther, E., Belsher, B., Botelho, R., Reed, A., . . . Kinoshita, T. (2009). Relationship between PTSD, Age, Education, and COWAT Responses in Older Veterans. Archives Of Clinical Neuropsychology, 24(5), 454-455.

Porter, James N., Collins, Paul F., Muetzel, Ryan L., Lim, Kelvin O., & Luciana, Monica. (2011). Associations between cortical thickness and verbal fluency in childhood, adolescence, and young adulthood. NeuroImage, 55(4), 1865-1877.

Oral, Elif, Canpolat, Serpil, Yildirim, Serap, Gulec, Mustafa, Aliyev, Elvin, & Aydin, Nazan. (2012). Cognitive functions and serum levels of brain-derived neurotrophic factor in patients with major depressive disorder. Brain Research Bulletin, 88(5), 454-459.