Attentional set shifting modulates the target P3b response in the Wisconsin card sorting test

For years the Wisconsin card sorting test (WCST) has been used as a test of frontal lobe function. Recent event-related potential (ERP) research has s hown large differences in the amplitude of P3b responses evoked by early an d late trials within each WCST series ([8]. Barcelo F., Sanz M., Molina V., Rubia FJ. The Wisconsin Card Sorting Test and the assessment of frontal fu nction: A validation study with event-related potentials. Neuropsychologia 1997,35:399-408). In this study, 16 normal subjects performed a WCST adapta tion to investigate the role of attentional set shifting in these WCST P3b effects. Two control tasks were designed to examine whether early-late WCST P3b changes reflect category selection (attention) or category storage (me mory) operations. Results suggest both a sharp P3b attenuation during shift WCST trials, followed by a gradual P3b buildup during post-shift trials. T his P3b modulation could not be attributed to selection or storage of simpl e sensory stimulus dimensions, nor was it observed when the new rule was ex ternally prompted by the first card in the WCST series. Instead, WCST P3b c hanges seem related to the endogenously generated shift in the perceptual r ule used to sort the cards (i.e., the shift in set). The gradual build-up i n P3b amplitude paralleled a progressive improvement in sorting efficiency over several post-shift WCST trials. A model based on formal theories of vi sual attention and attentional set shifting is proposed to account for thes e effects. The model offers firm grounds for prediction and bridges the gap between related clinical and experimental evidence. (C) 2000 Elsevier Scie nce Ltd. All rights reserved.