Electrophysiological indicants of black-white discrimination performance for letter and non-letter patterns

This study examined event-related potentials (ERPs) and behavioral measures, considered to be sensitive to the selective processing of black versus white letter and non-letter patterns, in a group of seventy-four randomly selected 6 to 8 year old children. Results demonstrated faster and more accurate behavioral performance on the experimental task for the letter than for the non-letter patterns. The ERP measures provided complementary information regarding this letter facilitation effect, indicating that the selective neural processing of letter as compared to non-letter patterns was present in the electrophysiological waveform within the initial 100-140 ms after stimulus presentation. Later ERP measures (200-260 and 500-600 ms post-stimulus) in response to the letter stimuli showed greater differences as a function of task relevance over the left than over the right hemisphere. The results from the present study indicate a remarkably early facilitative influence of stimulus type (letter versus non-letter patterns) on the luminance discrimination of these stimuli and are consistent with an overlap of linguistic and perceptual processing.