Non-verbal joint action in healthy adults: a systematic scoping review of EEG-hyperscanning research

Using EEG-hyperscanning, neuroscientists showed that non-verbal joint actions are associated with different patterns of interpersonal neural coupling (INC), influenced by factors such as the type of joint action investigated, the experimental task used, and the analytical approach employed. The present systematic scoping review aims to identify the categories of non-verbal joint actions investigated so far, the experimental tasks and INC measures used, and the related main findings to provide a comprehensive overview of the field. Thirty-nine articles were included in this review. Most studies investigated cooperative and simultaneous joint actions performed with either similar or complementary actions, whereas competitive and turn-based joint actions are under-investigated. Tasks involve interactions mainly based on movement, music, or computer, with movement-based tasks being most relevant to social neuroscience. Several INC approaches were used, with graph theory and phase synchrony being the commonly used. The main findings are organized and discussed according to the analytical approaches used and, for each approach, into groups of joint action categories and tasks. By providing a structured classification of joint action types and highlighting the relationship between tasks and INC methods, this review offers a reference for designing future studies and refining methodological approaches in EEG-hyperscanning research on social interaction.