Delayed P300 during Sternberg and color discrimination tasks in poor readers

The P300 ERP component was studied in poor and normal readers, using Sternb erg and color discrimination (Spaceships) tasks. During the first one, subj ects must decide if a probe item belongs or not to a set of digits previous ly presented. In the second one, the participants must shoot violet spacesh ips with one key and other than violet spaceships with another key. There w ere no significant differences between groups with respect to reaction time s, but a larger proportion of errors was observed in poor readers. Longer P 300 latencies were recorded for poor readers than controls in both tasks. P 300 amplitudes showed topographical differences between the two groups: Poo r readers' P300 is larger frontally during the Sternberg task, but smaller at posterior sites during the Spaceships task. These results suggest that p oor readers may have deficiencies during the early processing stage, such a s Visual stimulus evaluation. Poor readers also appear to have deficits for classifying and memorizing visual stimuli. (C) 2001 Elsevier Science B.V. All rights reserved.