Neurophysiology of grapheme decoding
The N170 as A Predictive and Descriptive Tool
This study zooms in on the specialization of visual processing that underlies grapheme and word form processing, and presents an electrophysiological experiment performed with 8th graders in a public state elementary school. The methodology of Event Related Brain Potential (EEG-ERP) was used to collect and analyze the N170 component, a neurophysiological signature sensitive to grapheme and word form processing. The test results indicated that, in this group, higher performance in grapheme recognition was not associated to a reduced difference between ERP wave amplitudes in response to word and false font stimuli, but instead to a clear left lateralization of print sensitive N170 responses. Differently from most ERP studies that uses the grand-averaging of all participants’ ERP responses, the current analysis also investigated individual performance of participants. In this modality, the varying levels of intensity and lateralization of the neurophysiological response indicate that a large portion of the participants remain in the process of obtaining reading fluency long after having started to learn how to read. The qualitative correlation between performance and the degree of lateralization is, thus, a novel and promising measurement involving the N170 component as a descriptive and predictive tool in the monitoring of reading acquisition stages.