These results prove that face-to-face communication is shaped by deeply ingrained prior expectations about how multisensory signals should be structured and interpreted, and raise fascinating and timely questions about the evolutionary, developmental and cultural origins of these priors.

We found that people have a stronger prior tendency to combine vocal and bodily signals when they convey the same communicative intent. Thus, the brain uses prior expectations to bind multisensory signals that carry converging communicative meaning.

We addressed this question by framing face-to-face communication as a Bayesian Causal Inference problem. Combining psychophysics with computational modelling, we formally tested whether prior expectations arbitrate between the integration and segregation of vocal and bodily signals.

Face-to-face communication is complex: what we say is coupled with bodily signals, which may or may not work in concert to convey meaning. How does the brain determine which multisensory signals belong together and which, instead, must be kept apart?