Clustering and switching as two components of verbal fluency: Evidence from younger and older healthy adults.

TLDR

Verbal fluency is a common neuropsychological test, yet the underlying cognitive processes are poorly understood; the authors propose that clustering and switching are key components of fluency performance. The study found that clustering and switching are distinct components, with switching more strongly linked to phonemic fluency and frontal‑lobe function, younger adults producing more words and switching more on semantic tasks, older adults forming larger phonemic clusters, and divided attention selectively impairing phonemic switching.

Abstract

Although verbal fluency is a frequently used neuropsychological test, little is known about the underlying cognitive processes. The authors proposed that 2 important components of fluency performance are clustering (i.e., the production of words within semantic or phonemic subcategories) and switching (i.e., the ability to shift between clusters). In Experiment 1, correlational data from 54 older and 41 younger adults indicated that both components were highly correlated with the number of words generated on semantic fluency, whereas switching was more highly correlated than clustering with the number of words generated on phonemic fluency. On semantic fluency, younger participants generated more words and switched more frequently than older participants; on phonemic fluency, older participants produced larger clusters than younger participants. In Experiment 2, among 22 young adults, divided attention decreased the number of words generated and decreased switching on phonemic fluency only. Overall, findings suggest that clustering and switching are dissociable fluency components and that switching is related to frontal-lobe functioning.