On the dissociation between clustering and switching in verbal fluency: comment on Troyer, Moscovitch, Winocur, Alexander and Stuss.
Troyer, Moscovitch, Winocur, Alexander and Stuss (Neuropsychologia 36 (1998) 499) used a procedure originally introduced by Troyer, Moscovitch and Winocur (Neuropsychology 11 (1997) 138) for distinguishing two different components of verbal fluency-clustering and switching-in frontal and temporal-lobe patients. Application of this procedure yielded results that suggested a frontal-lobe switching deficit, but intact 'clustering'. I demonstrate here that the proposed procedure may lead to incorrect conclusions because it does not allow an unambiguous dissociation between a general reduction in processing speed and a selective switching deficit. Some implications of this critique for inferences about the neurocognitive components involved in verbal fluency tasks are discussed.
Mayr
Ulrich
U
Department of Psychology, University of Oregon, Eugene, OR 97403, USA. mayr@oregon.uoregon.edu
D000328:Adult; D000367:Age Factors; D001927:Brain Diseases / Q000473:pathology / Q000523:psychology*; D016000:Cluster Analysis; D003071:Cognition; D005625:Frontal Lobe / Q000473:pathology*; D006801:Humans; D008568:Memory; D008960:Models, Psychological; D011930:Reaction Time; D012660:Semantics; D013702:Temporal Lobe / Q000473:pathology*; D014706:Verbal Learning