Verbal fluency test

A verbal fluency test is a kind of psychological test in which a participant is asked to produce as many words as possible from a category in a given time (usually 60 seconds). This category can be semantic, including objects such as animals or fruits, or phonemic, including words beginning with a specified letter, such as p, for example. The semantic fluency test is sometimes described as the category fluency test or simply as "freelisting", while letter fluency is also referred to as phonemic test fluency. The Controlled Oral Word Association Test (COWAT) is the most employed phonemic variant. Although the most common performance measure is the total number of words, other analyses such as number of repetitions, number and length of clusters of words from the same semantic or phonemic subcategory, or number of switches to other categories can be carried out. By means of curve fitting, temporal clusters, switches, and the initial slope can be determined. Whereas the total number of words and the initial slope indicate the global (macro) structure, clusters and switches evaluate the performance’s local (micro) structure. Verbal fluency tests have been validated as brief cognitive assessments for the detection of cognitive impairment and dementia in non-specialist clinical settings. The National Health and Nutrition Examination Survey (NHANES) administered the Animal fluency to over three thousand participants 60 years and older in 2011–2014. Trained interviewers administered the test at the end of a face-to-face private interview in an examination center. An extensive analysis of these data has been published. Scores (median, 25th percentile, 75th percentile) declined with age: 60-69y: 19, 15, 22; 70-79y: 16.0, 12, 20; 80+y: 14, 11, 17. Performance in verbal fluency tests show a number of consistent characteristics in both children and adults: A declining rate of production of new items over the duration of the task, which was long discussed as following either an exponential or a hyperbolic time course, which finally could be shown to be special cases of a unifying power function (the fused Bousfield function).