“Sharing of information” is one of the fundamentals of any interaction among humans, and any interaction including other kinds of participants. This article presents a theory of interaction by information sharing, regarding an interaction as: a set of internal processes constituted by participants’ first-person inferences, with which each participant, as a goal-directed adaptive information processing system, tries to change its internal state to make it easier to realize the composite goal state constructed by the participant’s first-person inference on goal states of the self, the second persons, and the third persons. It appends related studies from developmental science and cognitive neuroscience, and from the research on human-robot interaction conducted in our laboratory as well.
