On the reliability, validity, and cognitive structure of the Thurstone Word Fluency Test

The Thurstone Word Fluency Test (TWFT) is a widely used neuropsychological instrument. However, data regarding its psychometric properties are lacking. The results of the present study suggest that the TWFT possesses excellent test-retest and inter-rater reliability, in addition to good construct validity. However, its criterion validity is limited by its lack of specificity and sensitivity. The present study also suggests that the TWFT is a complex cognitive task, and that successful TWFT performance depends upon a constellation of cognitive abilities, including attention/concentration, psychomotor speed, and memory. Finally, the relationship between verbal IQ and TWFT letter association value was examined. While the TWFT appears to be useful in detecting the presence of cerebral dysfunction, it is of less value in localizing such dysfunction. It is argued that the TWFT should not be used as a neuropsychological screening instrument, but rather, is best used within the context of a thorough neuropsychological examination.