Bidirectional grapheme-phoneme activation in a bimodal detection task

A divided attention paradigm was used to investigate whether graphemes and phonemes can mutually activate or inhibit each other during bimodal processing. In 3 experiments, Dutch subjects reacted to visual and auditory targets in single-channel or bimodal stimuli. In some bimodal conditions, the visual and auditory targets were nominally identical or redundant (e.g., visual A and auditory /a/); in others they were not (e.g., visual U and auditory /a/). Temporal aspects of cross-modal activation were examined by varying the stimulus onset asynchrony of visual and auditory stimuli. Cross-modal facilitation--but not inhibition--occurred rapidly and automatically between phoneme and grapheme representations. Implications for current models of bimodal processing and word recognition are discussed.