From birth to five,
what do you look like
to your baby?

The full narration of the video.

At birth, you're a blur; by five, you can be fooled. In those five years, the parent in a baby's eyes changes shape several times. Let's crouch to baby height and watch. A newborn's eyes work like a camera that only shoots close up.

Within a foot or so, it's fairly clear: just the distance to your face during a feed. Any farther, it's fog. So the first way he knows you isn't through his eyes, but through his ears and nose. He heard his mother's voice for months in the womb. Two or three days after birth, he can pick it out from other voices.

At about a week, when he smells a pad his mother has worn, he turns his head toward it. And your face? In one experiment, four-day-old babies looked at their mother and at a woman they'd never met. They stared longer at their mother. They knew her.

But when both women wore headscarves over their hair, the babies could no longer tell which one was Mom. In those first days, he knows you first by the outline of hair around your face: your hairline. The eyes, nose and mouth in the middle take a few more months before he studies them closely.

Around eight months, the camera upgrades again: even when you're out of sight, he knows you still exist. When he was younger, cover a toy with a cloth and he'd stop looking. Now, the moment you walk out the door, he cries for you. This is called separation anxiety, and it usually peaks between ten and eighteen months. Crying hard means he remembers you.

Between eighteen months and two, secretly dab a red spot on his nose and hold him up to a mirror. He used to smile at the baby in the mirror like it was someone else's child. Now he reaches up and rubs his own nose. He's discovered that the one in the mirror is me. And you and I are two different people.

Looking up at you now, you're about twice his height, like an adult looking up at a giant over three meters tall. By three, this giant knows everything, as far as he's concerned. Take a cookie box, swap the cookies for stones, show him, then ask: Mom hasn't opened it, so what will she think is inside?

Most three-year-olds say: stones. If I know it, of course Mom knows it. By four or five, the answer changes: Cookies! Mom's going to be fooled. He realizes what's in your head isn't what's in his, and you can be fooled. This is called theory of mind: being able to guess what others are thinking.

In this camera, the lens is his eyes; what upgrades year after year is the brain behind them. From a blur, to a ring of hair, to an ordinary person who can be fooled. You barely changed. He did. The three-year-old who thinks you're a god, or the five-year-old who tricks you: which do you like more?