Clustering and Switching During Verbal Fluency in Typical and Atypical Development: A Systematic Review in Children and Adolescents

Empirical research studies have emphasized the importance of examining the strategic retrieval processes (i.e., clustering and switching) underlying verbal fluency (VF) performance. This systematic review aimed to summarize existing empirical studies on the development of clustering and switching strategies during VF in typically developing (TD) children and adolescents and further explore strategy use in children with atypical development (AD). A systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was conducted. Most studies used the scoring method developed by Troyer et al. (1997), and some used a combination of the other available approaches (e.g., Abwender et al.'s [2001] method considering the distinction between cluster switching [CS] and hard switching [HS]). The main results suggest that clustering and switching are components that follow distinct developmental trajectories. Indeed, most studies found that the number of clusters and switches, but not the mean cluster size, increases with age, with no differences based on sex. Both the number of clusters and the number of switches drive word productivity. Switches are highly related to VF phonological productivity, while clusters are most related to semantic productivity. Finally, different profiles are observed in AD, with patterns that distinguish between impairment in cognitive flexibility (less switching) and in the organization of semantic and phonological representations (smaller cluster size). This evidence highlights the importance of utilizing qualitative analysis of VF output for understanding strategic retrieval processes and lexico-semantic knowledge in children. Furthermore, it provides valuable data for informing the neuropsychological assessment of executive functions in children and adolescents with typical and atypical development.