Why do kids look at you before they cry?

The full narration of the video.

Same kid, same tumble. This time you gasp and rush over, and he bursts into tears. Another time you stay quiet, and he gets up and keeps running. So does it hurt or not? Does that really depend on you? Before you answer, try a little experiment. Picture yourself on a plane. Suddenly the cabin drops with a jolt.

What's the first thing you do? Lots of us look up and check the flight attendant's face. If she's still smiling and pouring coffee, you relax. If her face changes and she hurries to her seat, your heart jumps too. Why her? Because you can't tell on your own whether that bump is dangerous. She's flown thousands of times. You haven't.

When a small child falls, they've just boarded that plane. In that first instant, the body often reports fright before pain: the sky flips, the ground slams up, the heart pounds. There's pain too, but how serious is it? The brain has to judge. Adults have fallen hundreds of times and keep a mental ledger: this kind passes in a minute.

For a one- or two-year-old, that ledger is nearly blank. A big scare and a real injury are hard for them to tell apart. So what do they do? They borrow the most familiar face around. Babies start doing this at about seven to ten months, and by one year it's very common. In 1985, there was a famous experiment. One-year-olds crawled onto a thick sheet of glass. Beneath it, the floor suddenly dropped away, like a cliff.

Mom stood on the other side. When she smiled, about three in four babies crawled across. When she looked afraid, not one did. The babies weren't reading the glass. They were reading Mom. Researchers found flaws in that study, but other studies saw the same thing: the less certain the situation, the faster babies look to a grown-up. So how bad are most everyday tumbles? Researchers in Canada watched 52 children, aged one to two and a half, at an indoor play centre. On average, each child got a bump about once an hour.

Almost all were minor. One minute later, nearly every child was fine again. So children do feel the pain. What they don't know is whether this one is serious, so they look up at you and borrow your experience. If you shriek, what he reads is: something terrible happened. If you stay calm, he reads: it's okay, get up.

Of course, if it's a real injury, bleeding, swelling, crying that won't stop, or vomiting and unusual sleepiness after a knock to the head, don't brush it off. See a doctor. That glance at you is a question: is this bad? When you fell as a kid, what was the first thing the grown-ups said?