Complex sentence: At the age of 2 months, children engage in dyadic joint attention and conversation-like exchanges with adults during which each is the focus of the other's attention and they take turns exchanging looks, noises and mouth movements.
Split into simpler sentences: At the age of 2 months, children engage in dyadic joint attention and conversation-like exchanges with adults. During which each is the focus of the other's attention and they take turns exchanging looks, noises and mouth movements.