Visual information shows dominance in determining the magnitude of intentional binding for audiovisual outcomes

Intentional binding (IB) refers to the compression of subjective timing between a voluntary action and its outcome. In this study, we investigate the IB of a multimodal (audiovisual) outcome. We used a modified Libet clock while depicting a dynamic physical event (collision). Experiment 1 examined whether IB for the unimodal (auditory) event could be generalized to the multimodal (audiovisual) event, compared their magnitudes, and assessed whether the level of integration between modalities could affect IB. Planned contrasts (n = 42) showed significant IB effects for all types of events; the magnitude of IB was significantly weaker in both audiovisual integrated and audiovisual irrelevant conditions compared with auditory, with no difference between the integrated and irrelevant conditions. Experiment 2 separated the components of the audiovisual event to test the appropriate model describing the magnitude of IB in multimodal contexts. Planned contrasts (n = 42) showed the magnitude of IB was significantly weaker in both the audiovisual and visual conditions compared with the auditory condition, with no difference between the audiovisual and visual conditions. Additional Bayesian analysis provided moderate evidence supporting the equivalence between the two conditions. In conclusion, this study demonstrated that the IB phenomenon can be generalized to multimodal (audiovisual) sensory outcomes, and visual information shows dominance in determining the magnitude of IB for audiovisual events.