van Zuijen, T. L. & de Jong, P. F.
Department of Child Development and Education, University of Amsterdam, the Netherlands
Dyslexia and its accompanying cognitive impairments have recently been attributed to a problem in the long-term learning of serial-order information. In immediate serial recall tasks dyslexic adults did not benefit from the repetition of one particular sequence, whereas normal readers did. The absence of such a Hebb repetition effect suggests a domain general learning problem in dyslexia. In the present study we examined the Hebb repetition effect in dyslexic and normal reading children. We compared a group of 27 fourth grade poor readers with a group of 27 normal reading children. The groups were matched on age, non-verbal IQ, vocabulary and gender. Both a verbal-verbal and a visual-spatial serial recall task were administered. In the verbal-verbal task the children listened to sequences of six digits and responded verbally by repeating the sequence. In the visual-spatial task the children watched a frog appearing in six position on a computer screen and were instructed to respond by clicking on the positions in the correct serial order. In each task, every other sequence was repeated (Hebb trials) and performance on the Hebb trials was compared to the performance on the other varying sequences (filler trials). In both groups and on both tasks, we found an improved recall of the Hebb trials compared to the filler trials. Furthermore, the average readers were better in serial recall of both trial types compared to the poor readers, also on both tasks. Taken together, poor reading children performed worse on the immediate serial recall tasks compared to their normal reading peers but they did not show a smaller Hebb repetition effect. Our results do not support that there is a problem in the transfer of serial order information to long term memory in dyslexic children.