Automatic integration of letters and speech-sounds is necessary to establish fluent reading. In a recent event-related potentials (ERP) study we demonstrated early and automatic integration of letters and speech-sounds in adult readers within a narrow temporal integration window [1]. The present study further investigated when and how letter/speech-sound integration becomes automatic by employing the same ERP-paradigm in beginner (8y) and advanced (11y) readers. Speech-sounds were presented in isolation or in the context of letters appearing either simultaneously with or 200ms before the speech-sound.
As opposed to adult readers, no early effect of letters on speech-sound processing (at 150ms) was found in beginner readers. Instead, beginner readers exhibited a late deviant ERP response at 650ms. Even advanced readers, despite four years of reading instruction, showed the adult-like early effect (at 150ms) only for 200ms stimulus onset asynchrony. At simultaneous presentation of letters with speech-sounds, advanced readers revealed only a late effect (at 650ms).
The double shift in timing properties of letter/speech-sound processing (both in latency and temporal integration window) indicates a qualitative shift from mere association in beginner readers to automatic, but still not adult like, integration in advanced readers.
[1] Froyen, Van Atteveldt, Bonte, & Blomert, 2008, NSL.