games and activities. The infant-directed speech of adults also tracks these changes: the ratio of informative to noninformative (mere commenting) speech undergoes a complete reversal between 3 and 9 months. Only 38% of infant-directed speech at 3 months is informative, but 61% is informative at 9 months ( Boerse & Elias, 1994).
Not only do caregivers change their infant-directed speech at this time but they now begin to add to it a variety of actions that serve to gather and direct the child's attention: objects are held in front of a child and made to emit noises (either by manipulating them or by "supplying" the noises); objects are loomed up at and/or away from the child's face; patterns of repetition with crescendo and decrescendo increase in vocalizations; and a variety of rhythmic devices are used as well ( Zukow & Duncan, 1994).
In a sense, all subsequent social interaction emerges from dynamic triadic interaction-- it is the basic frame from which all varieties of human social interaction emerge and differentiate. From now on in the life of the child he or she will encounter objects, places, and events as one among many mobile people. They must learn to integrate their skills in regard to inanimate objects with their interaction skills to adapt to these increasingly complex social settings.
The child who has begun to master a dynamic triadic interaction frame has begun to be a person in the completest sense of the word. This young person has a set of skills and interests, which, however small and underdeveloped, are his or her own field of free action. And, important, among the skills is the ability to share objects, places, and events in the surroundings with others--to enter into all the varied forms of the dynamic triadic frame established by the culture. Indeed, he or she is not only capable of sharing but has also begun to learn how to indicate what is being shared, by gestures and vocalizations, emphasizing specific objects, places, or events in the stream of action, so as to promote the attention an action of his or her social partners.
These abilities involve powers of selection and choice that begin to define personality, disposition, and interests. Being mobile, infants can often choose what objects they want, or find a desired place, or engage in a selected event or activity. In addition, they can comprehend (at least up to a point) what the choices and selections of their caregivers mean, and they can even take steps to accommodate, reshape, or even thwart their caregivers' promotions.
Anthropologists have rightly come to be suspicious of reifying concepts like "culture" ( Wolf, 1982). Some, like Carrithers ( 1992, p. 34), suggest that concepts like interaction and social relations are more real than culture and therefore can be used to ground our thinking about human nature. Ecological psychology dovetails nicely with this trend in anthropological theorizing, because it gives a rich and dynamic meaning to interaction. In particular, as this chapter has shown, ecological psychology's understanding of sociality both gives us concrete insights into the development of interaction and helps us avoid theoretical dilemmas. Is human sociality reducible to the activities of individuals or is sociality itself irreducible? The answer to this theoretical