Babies don't learn to fear heights the way we've long thought they do

Science Friday

Fear of heights seems pretty normal and even sensible. But is it innate?

“Everyone has had some kind of an experience, feeling something kind of like fear of heights — and it makes perfect common sense that we shouldn’t jump off the edge of a drop-off because it’s dangerous. And if it's dangerous, then we should probably be afraid of it,” says Karen Adolph of New York University’s Infant Action Lab.

Developmental psychologists once referenced the "visual cliff" — an experiment that plops babies on a fake precipice — as proof that infants learn to fear heights as they learn to crawl.

Adolph’s research over the past 25 years reveals that while babies can learn from experiences near high ledges or narrow bridges, it's not a phobia they acquire. Exactly how and when this fear develops makes for pretty gleeful research in her lab, where babies crawl over surfaces to test their response to physical and visual obstacles that may or not be safe for them.

The visual cliff experiment by Eleanor Gibson and R.D. Walk in 1960 demonstrated the response by human and animal infants to a visual obstacle.

“It’s a glass table, and on one side there’s a checkboard pattern surface right under the glass. The other side of the table the patterned surface is way down on the floor. so visually it looks like a big three-foot drop-off,” Adolphs says. The experiment became a shaky foundation for the myth that crawling innately teaches us to fear heights.

The visual cliff, however, was a better test of the infant’s depth perception — and not their fear of heights. Watch closely, and you’ll notice that the babies — new crawlers — aren’t particularly scared and will crawl right onto the glass. But a baby with several weeks of crawling experience will begin to refuse to crawl over the drop-off, but will use their arms to feel their way through the obstacle. And they do so without fearful emotion.

It’s a development process that repeats as a baby learns to sit, crawl, cruise and walk, she says.

“If they were afraid of heights, you should just be afraid of heights. ... You shouldn’t see four different learning curves,” Adolph says.

So if babies aren’t learning to be afraid of heights, what are they learning?

Adolph believes that babies are learning to perceive the relation between their bodies and the environment. She says babies' responses become more accurate until they’re finally at adult-like levels and they can tell precisely whether a slope or a drop-off is safe for crawling on.

They’re discovering whats possible and what’s just a little too far.

“And you can learn that without feeling any sort of fear at all,” Adolph says.

This story is based on interviews from PRI's Science Friday with Luke Groskin

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