What should I do next? Using shared representations to solve interaction problems

Studies on how the social mind" works reveal that cognitive agents engaged in joint actions actively estimate and in uence another's cognitive variables, and form shared representations with them. (How) do shared rep- resentations enhance coordination? In this paper we provide a probabilistic model of joint action that emphasizes how shared representations help solv- ing interaction problems. We focus on two aspects of the model. First, we discuss how shared representations permit to coordinate at the level of cog- nitive variables (beliefs, intentions and actions), and determine a coherent unfolding of execution and predictive processes in the brains of two agents. Second, we discuss the importance of signaling actions as part of a strategy for sharing representations and the active guidance of another's actions to- wards the achievement of a joint goal. Furthermore, we present data from a human-computer experiment (the Tower Game) in which two agents (human and computer) have to build together a tower made of colored blocks, but only the human knows the constellation of the tower to be built (e.g., red- blue-red-blue-. . . ). We report evidence that humans use signaling strategies that take another's uncertainty into consideration, and that in turn our model is able to use humans' actions as cues to align" its representations and to select complementary actions.