Babies are born communicators. Even before birth, they recognize their mothers’ voices. They know to look at mouths and eyes—the parts of the face that convey the most meaning. They pay attention to the rhythms of speech and movement. A one-month-old responds to an upset tone of voice with agitated movements and a faster heart rate. A soothing voice has the opposite effect.
Babies come to know the important people in their lives by how parents and other caregivers make them feel. They learn to expect comfort from people who hold them gently and talk quietly, excitement from those who toss them in the air and twirl them around. If a parent behaves unexpectedly—for example, by acting distant or unresponsive—babies get confused or they get angry.
Babies pick up on these nonverbal signals, and they also send them. You can see the look on your baby’s face that means “talk to me”: eyes wide open, mouth slightly pursed. And you can tell when your baby needs a break from too much stimulation: he might look away and his eyelids might come down; her chin might start to shiver, or she might yawn. Some babies show stress subtly: the skin around their mouths becomes pale. And not so subtly: others throw up.
By four months, babies are experts at emotional communication. They put out clear signals, watch for the responses that come back, and respond in turn. Some experts describe the action as the “serve and return” of a tennis match; others talk about the “dance.” When I see a four-month-old for a checkup, I ask his mom if they have started to have long conversations yet. Very often, the answer is yes. They aren’t talking in words, but they understand each other’s face, body, and tone of voice. When words actually begin to make sense, mother and baby build on this nonverbal foundation. “Reading” starts long before you pick up your baby’s first board book. It starts when you read your baby, and your baby reads you.