lW)?X 393?,XX $3 ~x)+o.oll Prrpa m o n Pre ra p lc zyxwvutsrqp THE DEVELOPMENT OF LATERAL EVENT-RELATED POTENTIALS (ERPs) RELATED TO WORD NAMING: A FOUR YEAR LONGITUDINAL STUDY ROBERT LICHT*~, DIRK J. BAKKER*~, ALBERT KOK~ and ANKE BOUMA? *Paedological Institute*. tFree University, and $University of Amsterdam. Amsterdam. The Netherlands zyxwvutsrqponmlkjihgfe (Receiwd 17 April 1986; accepted 12 Junr 1987) Abstract---Event-related potentials (ERPs) were recorded from the left and right temporal and parietal sites during a word naming task. Subjects were a group of children that were followed over four consecutive years starting at Kindergarten. ERP waveforms contained a sequence of positive and negative components (N150, P240. N360, N530 and SW). All components, except Nl50, showed changes in amplitude as a function of age, whereas SW, N360 and N150 also changed in hemispheric distribution. In addition, a relationship was found between reading performance and ERP amplitudes over the right parietal hemisphere in young children, and over the left temporal hemisphere in older children. Proficient readers showed larger (more negative) parietal N530 amplitudes than less proficient readers, especially when stimuli were degraded words. The results are discussed in terms of age-related changes in right and left hemisphere functions involved in early and advanced stages of reading. that might possibly be related to visual word recognition. INTRODUCTION IT IS WELL documented that the reading of text is affected by perceptual, syntactic and semantic aspects of script. There is evidence to suggest that the relative importance of these aspects of reading performance depends on the stage of the learning to read process. Perceptual processes, like visual discrimination and recognition, are predominant in early reading, while semantic and linguistic processes contribute most to the advanced stages of reading [l, 5,14,37]. It has been suggested that the developmental change from a perceptual to a linguistic mode of cognitive processing in reading is related to a change from right to left hemispheric mediation of some of the reading components [I, 321. Right hemispheric (RH) processing of text by novice readers may be invoked primarily by the perceptual aspects [I, 2, 31 and novelty of script [18]. In a similar way, left hemispheric (LH) processing of text by experienced readers may be elicited by the semantic aspects of script. Evidence supporting this view has been derived primarily from cross-sectional behavioural studies employing visual half-field techniques, e.g., CARMON et al. [S]; BROMAN [6]; and SILVERBERG et ul. [36]. Another method to investigate the changes in hemisphere-specific functioning during learning to read is the event-related potential (ERP) technique. This technique enables a more direct investigation of the differential involvement of the hemispheres during the processing of words. Several studies have shown that the ERPs in young children are characterized by late negative waves (i.e., 40(X 500 msec) and late positive waves (i.e., lCorrespondence to bc addressed to Robert Licht, Free University!Paedological Institute. Department of Developmental Neuropsychology, Koningslaan 22. 1075 AD Amsterdam. The Netherlands. 327