2 to 3 months: Beginning to engage

He's 2 months old, sitting in a bouncy seat, watching his mother sponge the kitchen counters, enjoying himself. This strange world that he was born into is starting to make more sense. She opens the refrigerator and he turns his head toward the kiss of the door's suction; he's now able to identify what he's hearing and has enough coordination to turn his body toward the sound. She pours herself a glass of orange juice and he notes the color. His vision is now 20/125 to 20/120.

Banging his hands up and down, he lets loose a shriek of joy. Development in his brain's circuitry now allows him to coo and squeak. Yesterday, when his grandmother spoke to him in Chinese, he detected subtle nuances in the sounds far better than his non-Chinese-speaking mother. By 6 months, he will start to ignore the nuances of this language he hears less frequently as he develops his skill for the one he needs to pay attention to most: English.

"What will you wear today?" his mother asks.

"Eeeeeeeee."

Drool drips onto his chin, but he doesn't feel it; his excitement at making sounds overrides the fact that his salivary glands are pumping out more fluid than he knows how to swallow. He doesn't even know that swallowing will prevent the drooling.

"Eeeeeeeee. That sounds good," she says, pulling back her lips.

Watching her, he begins to understand that that's how his lips look when he makes that sound.

"Eeeeeeeee," he repeats, mimicking her face.

When his mother turns on the radio and then answers the phone, he continues to follow her voice. His hearing is sophisticated enough to pluck out his mother's voice from the music on the radio; recognizing his mother's voice is a skill a baby is born with. But if there are too many background noises that are similar in tone, they blur together, making it harder for him to hear the differences.

To occupy him while she's on the phone, his mother rolls a ball by his bouncy seat. In his first weeks of life, his eyes would occasionally wander, but now they move in tandem more smoothly. His eyes follow the ball until it disappears behind the bookcase. It doesn't come back out. Gone. Out of sight, out of mind.

4 to 5 months: Grab that ring

Lying on the floor beneath his baby gym, he looks up at the yellow plastic ring and for the first time sees the inner surface of the ring's curve. Because his eyes move together now with more consistency, he has new depth perception. Swinging his arm up, he wraps his fingers around the hard plastic. Victory! He shrieks with excitement. All his weeks of practice have strengthened the neural pathways that direct his muscles to grab successfully.

He's also been practicing babbling. Now he's able to repeat many of the vowel sounds he hears when his mom talks to him, as well as mimic the way her mouth moves.

In the afternoon, his mom places him on his stomach on the floor. Pressing his arms into the carpet, he hoists up his head, neck, and trunk in a mini-push-up. In one quick turn, he rolls from his tummy to his back, a complex achievement of muscle and the stirrings of a new desire to move.

6 months: Starting to move

He coos, hoping his mom will look at him. He smiles, hoping to beguile her. She walks by and he cranes his neck to keep her in sight as long as possible. While he long ago "bonded" with her, he's just starting to truly long for her, preferring her above all others. His emotional life has taken a leap. Deep structures in his brain called the limbic system are now better able to connect his actions with specific feelings. He's not cooing for the fun of it, he's cooing because she makes him happy.

She rolls a ball across the room. The game is more interesting to him now that his vision is at least 20/80 to 20/100. The ball disappears behind the bookcase, but now he looks to the other end, confident it will reappear. His brain can retain the visual image of the ball even when it's not in sight, and he understands that it still exists and is still moving.

His mother leaves the room to make a cup of tea and he watches her until he can't see her anymore. As with the ball, he knows that she continues to exist, even though he can't see her. But that's no comfort  -- he wants her.

He balls his fists, brings them to his mouth, and cries out in frustration. Blood rushes to his face. He has no understanding of time, doesn't know how long she'll be gone or why she left. All he knows is that she's gone.

He bends his right leg, trying to will his body into crawling, moving toward her. It feels like he could, but he doesn't really know how. He works and works at it. He's not ready yet but will be soon.

She returns, scoops him up, and his cries subside as he squirms with happiness. All is well.

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