Gesture and speech are tightly coordinated during communication, yet the mechanisms underlying this coordination remain debated. The interactive view proposes that gesture and speech can influence each other not only during planning but also during execution, whereas the ballistic view holds that interaction is limited to pre-execution stages. To test these competing theories, four experiments investigated whether disrupting one modality affects the execution of the other. Participants named and gesturally depicted geometric shapes and motion events while gesture or speech was disrupted using virtual reality, motion tracking, delayed visual or auditory feedback, and stimulus changes. In all experiments, disrupting one modality consistently prolonged the execution time of the other modality. Moreover, the magnitude of execution prolongation in one modality was related to that in the other. These results show that gesture and speech remain continuously and bidirectionally connected during execution, providing strong support for the interactive view.
Chu et al. (Sun,) studied this question.