Entrainment and Modulation of Gesture-Speech Synchrony Under Delayed Auditory Feedback

Gesture-speech synchrony re-stabilizes when hand movement or speech is disrupted by a delayed feedback manipulation, suggesting strong bidirectional coupling between gesture and speech. Yet it has also been argued from case studies in perceptual-motor pathology that hand gestures are a special kind of action that does not require closed-loop re-afferent feedback to maintain synchrony with speech. In the current pre-registered within-subject study, we used motion tracking to conceptually replicate McNeill's () classic study on gesture-speech synchrony under normal and 150 ms delayed auditory feedback of speech conditions (NO DAF vs. DAF). Consistent with, and extending McNeill's original results, we obtain evidence that (a) gesture-speech synchrony is more stable under DAF versus NO DAF (i.e., increased coupling effect), (b) that gesture and speech variably entrain to the external auditory delay as indicated by a consistent shift in gesture-speech synchrony offsets (i.e., entrainment effect), and (c) that the coupling effect and the entrainment effect are co-dependent. We suggest, therefore, that gesture-speech synchrony provides a way for the cognitive system to stabilize rhythmic activity under interfering conditions.