Successful outcome of a joint task requires successfully predicting and coordinating with others (Sacheli et al., 2015). It has been proposed that `two-persons neuroscience' (Schilbach et al., 2013) is a more appropriate conceptual and methodological framework to study the physiological basis of human social interaction. This entails developing experimental paradigms involving two interacting persons, with a focus on dyads rather than single individuals (Hari and Kujala, 2009). Nevertheless, interactive tasks has been mainly used to investigate the motor aspects of interpersonal coordination (Moreau et al., 2018; Sacheli et al., 2012), while the role of somatic representations in the context of joint action is still unexplored.
The brain maintains and continuously updates a multimodal representation of the body: a body schema (Holmes & Spence, 2004). Research has shown that extra-corporeal objects can be incorporated into the neural representation of the body schema (Carlson et al., 2010; Maravita et al., 2002; Cardinali et al., 2009). However, little is known on the possibility to incorporate parts of others' body in our own body schema.
The aim of our project is to investigate the neural dynamics underlying the formation of an interpersonal joint body schema during an interactive task involving two partners. Participants will engage in a joint task which requires coordination and mutual adjustments with a partner. After completing the task, we will measure brain activity with EEG to probe the 'entanglement' of the participant's body schema as a result of the interaction.
The proposed research represents a pioneer study in the field of social neuroscience and will help to clarify the neural dynamics underlying interpersonal shared bodily representations, with broader implications for developmental, clinical, and systems neuroscience.
Being in interaction with someone relies upon representations held collectively by both interactors rather than by each individual alone. Moreover, social interactions are often complex, dynamic and nonlinear (Froese & Di Paolo 2010; Port & van Gelder 1995; Thelen & Smith 1994) and therefore social cognition is fundamentally different when we are in interaction with others rather than merely observing them (Schilbach et al., 2013). For these reasons, proceedings in the field of social neuroscience requires a shift from studies on individual participants to those focusing on dyads.
Interactive paradigms has been used to study the mechanisms underlying joint attention, action observation, task sharing, action coordination and agency (Sebanz, 2006) as well as in pioneering experiments investigating the brain-behaviour dynamics of visuo-motor integration during social interaction (Tognoli et al., 2007; Dumas et al., 2010; Naeem et al., 2012; Ménoret et al., 2014; Konvalinka et al., 2014; Novembre et al., 2016). However, multisensory representations of body schema in interactive task are still unexplored.
Our project could describe for the first time how the brain is capable of creating a temporally extended bodily representation which is referenced on the dyad and could affects behaviour even after the joint task is completed. This could entail, for example, that during dancing with a partner we adjust our own body schema to coordinate with our partner, and that adjustments continues even when no longer dancing.
This could also lead to identify novel neural markers of entangled mental representations across individuals, and possibly open new perspectives in the field of distributed cognition and interbrain interconnectivity (Astolfi et al., 2010; Babiloni and Astolfi, 2014; Dumas et al., 2010; Konvalinka et al., 2014).
Moreover, understanding the dynamics underlying joint embodied representations could also have crucial implications for our understanding of typical and atypical neurodevelopment, where mother-child dyadic interaction has been shown to be crucial for the development of cognitive functions (Johnson, 2000; Meltzoff, 2007; Hobson 2008). This would also lead to a better understanding of psychiatric conditions characterized by reduced capacity to 'attune' with others, such as Autism Spectrum Disorder (Trevarthen & Aitken, 2001).
Future developments of this experiment will be further investigating the neural dynamics underlying entangled body schemas by simultaneously recording EEG from two participants during and after the task execution. Moreover, we, we aim to measure higher-order, cognitive and affective, effects of this joint body schema establishment, or test this paradigm on clinical populations, in particular Autism Spectrum Disorder.