Abstract
Previous studies suggested that attention modulates how well we integrate sounds with visual cues. In the present study, we examined attention effects on integration of written and heard syllables in fluent readers. Subjects were presented with auditory stimuli (consonant-vowel syllables) together with synchronized visual stimuli, which differed between conditions. The auditory stimuli included consonant and pitch changes. Visual stimuli were sound-congruent written syllables or their scrambled images. In four different attention conditions, subjects pressed a button to duration changes in 1) the visual modality, 2) auditory modality or 3) either modality, or 4) counted mentally backwards and ignored the auditory and visual stimuli. Preliminary analysis showed in event-related potentials to spoken syllables larger mismatch negativities (MMNs) to pitch changes during audiovisual, auditory, and visual tasks than during mental counting indicating that attention to either one or both modalities facilitated MMN elicitation, that is, even during the visual task, attention spread covertly to coinciding speech sounds, integrating written syllables with their spoken counterparts. Additionally, these MMNs were larger in all four conditions when the visual stimuli were syllables than when they were scrambled images, indicating that written syllables facilitated processing of coinciding spoken syllables independent of attention.