2019 Volume 37 Issue 3 Pages 157-165
Early processing of print stimuli is reflected by the left-lateralized N170 of event-related potentials (ERPs). However, most previous ERP studies have focused on letter strings, and only a few have investigated single letters in opaque alphabetic writing systems, despite the fact that they are the front-end of visual word recognition and reading development. We examined ERPs for single letters of the highly transparent Japanese Hiragana script, which demonstrated a direct correspondence between graphemes and phonemes. We presented single Hiragana letters along with control stimuli (alphanumeric symbols in Experiment 1; unfamiliar foreign letters in Experiment 2) in rapid succession. The participants were asked to judge the stimulus colors and linguistic properties of letters that were task-irrelevant. In both experiments, Hiragana letters elicited more negative enhancement than control stimuli in the left hemisphere only, which showed a different pattern from the bilateral enhancement associated with single alphabetic letters. These results suggest that the implicit sound activation of Hiragana is automatic, which extends the “phonological mapping hypothesis” on the left-lateralization of N170 onto single letters.
