Clustering and switching in verbal fluency: a comparison between control and individuals with brain damage.
Karina Carlesso Pagliarin, Eduarda Giovelli Fernandes, Maryndia Diehl Muller and 3 others
PMID 34816946WHAT IT FOUND
Patients with left-hemisphere damage and aphasia scored lowest on verbal fluency tasks, producing fewer words, clusters, and switches than all other groups.
Right-hemisphere patients showed specific deficits in switching between categories despite normal total word counts.
Key findings
01The left-hemisphere damage with aphasia group performed worse than all other groups on both semantic and phonemic verbal fluency tasks.
02Right-hemisphere damage patients made significantly fewer switches than controls on semantic tasks, even though their total word count did not differ from controls.
03Left-hemisphere damage patients without aphasia produced fewer words than controls in the first 30 seconds of semantic tasks, suggesting initiation deficits.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
Time since stroke was not controlled for in comparisons between clinical groups, which may confound recovery levels. Lesion locations were not specified for the right-hemisphere and left-hemisphere-no-aphasia groups, preventing precise correlation of specific brain regions with deficits. Some results approached significance but did not reach the p < 0.05 threshold, suggesting potential type II errors or underpowered comparisons for specific sub-measures.
The easy way to misread this
Do not assume that a patient with right-hemisphere damage has intact verbal fluency because their total word count is normal. This study found that RHD patients produced the same number of words as controls but had significantly fewer switches, meaning they struggled to shift between categories. Focusing only on quantity misses this qualitative deficit.