How is visual recognition entrained by auditory background rhythms?

Résumé 0

Recent studies have reported that the oscillations of auditory attention entrained by a background rhythmic sequence can influence performance in visual recognition tasks. We have designed an experimental paradigm in which a visual item (either a bisyllabic word or a familiar face) is displayed on screen in two consecutive parts while a musical rhythm is played in the background. Depending on the timing conditions, the first or the second part of the item could be presented either in-synchrony or out-of-synchrony with the beats of the auditory rhythm. In a first series of experiments, participants performed a lexical decision task on bisyllabic 5-letter strings. Results show that when the correct first syllable of a visual word (e.g., pan in pan.da) is presented on-beat, recognition is significantly enhanced compared to an off-beat presentation. However, if an incongruent first syllable (e.g., pa in pan.da) is presented on-beat, word recognition is highly impaired. This kind of interaction between the syllabic segmentation and rhythmic synchrony was not observed for the second part of the word. In this case, synchrony only had a positive main effect on word recognition. Overall, these results show that cross-modal temporal expectations not only affect perceptual or motor levels of processing stages but also impact more central stages of word recognition such as the processing of the first syllable. In a second series of experiments (still under way), we wanted to confirm these results using different visual materials. Here, participants had to report if the upper part of a face (containing the eyes) belonged to a familiar person or not, whether the lower part (containing the mouth) was congruent or not with the person to be recognized. Preliminary results show that the recognition of faces that are segmented in time could also be influenced by the oscillations of auditory rhythmic attention.