Clarifying the interaction types in two-person neuroscience research

Human brains and behaviors are shaped, and normally function, in continuous interaction with other humans (Hari and Kujala, 2009). However, because of the methodological difficulties related to the complex dynamics of interaction situations, neural mechanisms underlying interactive behavior remain one of the most poorly understood areas of neuroscience (Hari et al., 2013). Previous neuroscience research has argued that social processes enabling us to interact with others are internalized and hence can be understood by investigating individual brains (see Konvalinka and Roepstorff, 2012). Based on this assumption, neuroscience studies have mainly examined social cognition from a perception perspective by presenting single participants with socially-relevant pictures or videos (Lieberman, 2007). Although this has led to identification of a set of regions composing our “social brain,” such as amygdala, orbital frontal cortex, medial prefrontal cortex, and mirror neuron system (Frith, 2007), little is still known about how these brain regions function and transfer information between brains in dynamic, real-time interactions. Especially, more recent ideas have proposed that social cognition may be fundamentally different when an individual does engage in an interaction, rather than when one just observes the situation itself (Schilbach, 2010).