Got rhythm…for better and for worse. Cross-modal effects of auditory rhythm on visual word recognition

The present research aimed to investigate whether, as previously observed with pictures, background auditory rhythm would also influence visual word recognition. In a lexical decision task, participants were presented with bisyllabic visual words, segmented into two successive groups of letters, while an irrelevant strongly metric auditory sequence was played in a loop. The first group of letters could either be congruent with the syllabic division of the word (e.g. val in val/se) or not (e.g. va in va/lse). In agreement with the Dynamic Attending Theory (DAT), our results confirmed that the presentation of the correct first syllable on-beat (i.e. in synchrony with a peak of covert attention) facilitated visual word recognition compared to when it was presented off-beat. However, when an incongruent first syllable was displayed on-beat, this led to an aggravation of impaired recognition. Thus, our results suggest that oscillatory attention tapped into cognitive processes rather than perceptual or decisional and motor stages. We like to think of our paradigm, which combines background auditory rhythm with segmented visual stimuli, as a sort of temporal magnifying glass which allows for the enlargement of the reaction time differences between beneficial and detrimental processing conditions in human cognition.