Social cognition in general, and rhythmic entrainment in particular, have previously mainly been studied in settings where isolated individuals perform controlled tasks.

Recently, a number of alternative approaches have been developed to redefine what constitutes the “cognitive system”. In addition to the individual mind/brain, the body, the social context, and musical instruments should be included in the analytical framework. In general, this means studying cognition and behaviour at settings that are as naturalistic as possible. Music and dance are ideal domains for studying these phenomena, as naturally social, embodied activities.

Extending the traditional setting poses many challenges. I make the case for focusing the analysis on the interaction of multiple participants, instead of trying to measure the performance or mind-states of the individuals. This interactionist approach requires a specific set of analysis tools. For this purpose, I distinguish rhytmic synchronisation from entrainment between mutually cooperative individuals. I discuss a range of options from circular statistics to cross-recurrence analysis to various correlation-based analyses.

Through a number of pilot studies, I developed a cooperative tapping setup for studying rhythmic entrainment in dyads. Using this setup, I compared human–human interaction to synchronising with a computer. Surprisingly, two human tappers reached better synchronicity than a human with a computer tapper, even though the human pairs drifted in tempo. This demonstrated the power of mutual adaptation.

In a second series of experiments, motion capture was used to investigate the embodied nature of rhythmic entrainment. These cross-cultural studies on African dance, illustrated in more detail how synchronicity was achieved through a process of continuous, mutual adaptation. We observed interesting contrasts in how Finnish novices and South-African or Kenyan experts exhibited embodied metrical structures.

As a conclusion, mutual adaptation is a powerful and ubiquitous phenomenon that can only be observed in real-time interactions. It is a good example of the kind of “new psychology” that can be uncovered by adopting a social, embodied, and dynamic approach to cognition.