Human communication is a complex and multifaceted phenomenon in which language represents the most evolved and versatile interactive behavior. Language is multipurpose, allows for the expression of desires and internal states, is based on a shared, specific, and ultra-compressed code, and enables creative communication of higher forms of representation. At the same time, a significant part of the information exchange that takes place between people, is conveyed by body movements. Indeed, we have shown that body movements convey implicit sub-symbolic coordinative signals on multiple scales, which are nevertheless essential for interaction.
In this framework, the motor system acts as a filter/classifier of other peoples' actions, as human movements are characterized by invariants, arising from neural and biomechanical constraints. The observer is not naive about these regularities. In fact, each of us implicitly learns these regularities in the course of development and exploits this knowledge to support smooth interpersonal coordination. This means that natural communication is inherently multimodal and sensorimotor. The action-perception circuit mediates sensorimotor communication and causes automatic and implicit reciprocal behavioral coadaptation during interaction.
Importantly, in addition to movement regularities, we recently demonstrated that a small but systematic degree of variability characterizes individual motor actions (Individual Motor Signatures – IMS). The study of IMS opens up important new lines of research, both theoretical and applied. On the one hand, this framework allows us to study the computational mechanism that enables decoding of others' action and making sensorimotor coordination smooth; on the other hand, it helps us progress toward an individual-level quantitative neuroscience.