Social by Default: Characterizing the Social Functions of the Resting Brain

Social-neuroscience research has identified a set of medial frontoparietal brain regions that reliably engage during social cognition. At the same time, cognitive-neuroscience research has shown that these regions comprise part of the default network, so named because they reliably activate during mental breaks by default. Although the anatomical similarity between the social brain and the default brain is well documented, why this overlap exists remains a mystery. Does the tendency to engage these regions by default during rest have particular social functions, and if so, what might these be? Here, it is suggested that the default network performs two critical social functions during rest: social priming and social consolidation. These constructs will be defined, recently published empirical findings that support them will be reviewed, and directions for future research on the topic will be proposed.