抄録
Social ability seems to play a major role in the ontogeny of language. Human babies are already sensitive to adults' eye gaze, and follow it at an early age. At the first year of life, they begin to redirect the adults' attention and actively establish joint attention with caregivers and other important adults. They then use the established joint attention to guess meanings of words they hear. Later, children further show socio-pragmatic ability at a higher level to guess word meanings. They still use joint attention but they may not depend upon joint attention in some situations. Flow-of-conversation and guessing others' internal conditions can also give important cues for language development.
