part of the second, and the gesture of the second organism in turn calls out a response in the first person. On this level no communication occurs. Neither organism is aware of the effect of its own gestures upon the other; the gestures are nonsignificant. For communication to take place, each organism must have knowledge of how the other individual will respond to his own ongoing act. Here the gestures are significant symbols. A significant symbol is a kind of gesture that only humans can make. Gestures become significant symbols when they arouse in the individual who is making them the same kind of response they are supposed to elicit from those to whom the gestures are addressed. Only when we have significant symbols can we truly have communication. Mead grounded human perception in an "action-nexus". We perceive the world in terms of the "means of living." To perceive food, is to perceive eating. To perceive a house, is to perceive shelter. That is to say, perception is in terms of action. Mead's theory of perception is similar to that of J. J. Gibson. Social acts Mead argued in tune with Durkheim that the individual is a product of an ongoing, pre-existing society, or more specifically, social interaction that is a consequence of a sui generis society. The self arises when the individual becomes an object to themselves. Mead argued that we are objects first to other people, and secondarily we become objects to ourselves by taking the perspective of other people. Language enables us to talk about ourselves in the same way as we talk about other people, and thus through language we become other to ourselves. In joint activity, which Mead called social acts, humans learn to see themselves from the standpoint of their co-actors. A central mechanism within the social act, which enables perspective taking, is position exchange. People within a social act often alternate social positions (e.g., giving/receiving, asking/helping, winning/losing, hiding/seeking, talking/listening). In children's games there is repeated position exchange, for example in hide-and-seek, and Mead argued that this is one of the main ways that perspective taking develops. However, for Mead, unlike Dewey and J. J. Gibson, the key is not simply human action, but rather social action. In humans the "manipulatory phase of the act" is socially mediated, that is to say, in acting towards objects humans simultaneously take the perspectives of others towards