The verbal fluency test is a timed assessment that measures the ability to remember as many words as possible for a selected category. Categories are typically either semantic or phonemic. Semantic verbal fluency requires remembering as many words as possible that belong to a specific group or meaning, such as animals or sports teams. Phonemic verbal fluency requires remembers as many words as possible that have the same first letter, such as words beginning with the letter "A."
Verbal fluency can be measured by the total number of correct responses, or it can be analyzed more deeply by how responses are clustered (i.e., animals found in a zoo, animals in the ocean or foods beginning with letter A, household items beginning with letter A). Verbal fluency requires the ability to sustain attention and quickly switch category clusters in order to remember a high number of correct words. People with a traumatic brain injury often experience difficulty with verbal fluency, as problems with attention and the ability to cluster information are common. Age can also be a factor on how well a person performs either verbal fluency test. Studies have found that older age can be associated with worse performance on semantic verbal fluency than phonemic verbal fluency.
A recent study measured performance on both semantic and phonemic verbal fluency tests with young adults who had a traumatic brain injury, as compared to non-injured young adults. As expected, those with traumatic brain injury performed worse overall, remembering the fewest words in each category. However, the researchers found that those with a traumatic brain injury tended to perform worse in the phonetic verbal fluency tests than in the semantic test. Specifically, the traumatic brain injury participants had difficulty clustering words within phonetic categories. This finding contrasts previous research of worse performance with semantic categories within older adults.
Cralidis A & Lundgren K. Component analysis of verbal fluency performance in younger participants with moderate-to-severe traumatic brain injury. Brain Injury. (April 2014).