Before babies acquire an adult-like visual capacity, they participate in a social world as a human learning system which promotes social activities around them and in turn dramatically alters their own social participation. Visual input becomes more dynamic as they gain self-generated movement, and such movement has a potential role in learning. The present study specifically looks at the expected change in motion of the early visual input that infants are exposed to, and the corresponding attentional coordination within the specific context of parent-infant interactions. The results will be discussed in terms of the significance of social input for development.