Why all babies love peekaboo

Peekaboo is a game played over the world, crossing language and cultural barriers. Why is it so universal? Perhaps because it’s such a powerful learning tool.

One of us hides our eyes and then slowly reveals them. This causes peals of laughter from a baby, which causes us to laugh in turn. Then we do it again. And again.

Peekaboo never gets old. Not only does my own infant daughter seem happy to do it for hours, but when I was young I played it with my mum (“you chuckled a lot!” she confirms by text message) and so on back through the generations. We are all born with unique personalities, in unique situations and with unique genes. So why is it that babies across the world are constantly rediscovering peekaboo for themselves?

Babies don’t read books, and they don’t know that many people, so the surprising durability and cultural universality of peekaboo is perhaps a clue that it taps into something fundamental in their minds. No mere habit or fashion, the game can help show us the foundations on which adult human thought is built.

An early theory of why babies enjoy peekaboo is that they are surprised when things come back after being out of sight. This may not sound like a good basis for laughs to you or I, with our adult brains, but to appreciate the joke you have to realise that for a baby, nothing is given. They are born into a buzzing confusion, and gradually have to learn to make sense of what is happening around them. You know that when you hear my voice, I’m usually not far behind, or that when a ball rolls behind a sofa it still exists, but think for a moment how you came by this certainty.

The Swiss developmental psychologist Jean Piaget called this principle ‘object permanence’ and suggested that babies spent the first two years of their lives working it out. And of course those two years are prime peekaboo time. Looked at this way, the game isn’t just a joke, but helps babies test and re-test a fundamental principle of existence: that things stick around even when you can’t see them.

Maybe evolution fixed it so that babies enjoy peekaboo for its own sake, since it proved useful in cognitive development, but I doubt it. Something deeper than mere education is going on.

Surprise element

Peekaboo uses the fundamental structure of all good jokes – surprise, balanced with expectation. Researchers Gerrod Parrott and Henry Gleitman showed this in tests involving a group of six-, seven- and eight-month-olds which sound like more fun than a psychology experiment should be. Most of the time the peekaboo game proceeded normally, however on occasion the adult hid and reappeared as a different adult, or hid and reappeared in a different location. Videos of the infants were rated by independent observers for how much the babies smiled and laughed.

On these “trick trials” the babies smiled and laughed less, even though the outcome was more surprising. What’s more, the difference between their enjoyment of normal peekaboo and trick-peekaboo increased with age (with the eight-month-olds enjoying the trick trials least). The researchers’ interpretation for this is that the game relies on being able to predict the outcome. As the babies get older their prediction gets stronger, so the discrepancy with what actually happens gets larger – they find it less and less funny.

The final secret to the enduring popularity of peekaboo is that it isn’t actually a single game. As the baby gets older their carer lets the game adapt to the babies’ new abilities, allowing both adult and infant to enjoy a similar game but done in different ways. The earliest version of peekaboo is simple looming, where the carer announces they are coming with their voice before bringing their face into close focus for the baby. As the baby gets older they can enjoy the adult hiding and reappearing, but after a year or so they can graduate to take control by hiding and reappearing themselves.

In this way peekaboo can keep giving, allowing a perfect balance of what a developing baby knows about the world, what they are able to control and what they are still surprised by. Thankfully we adults enjoy their laughter so much that the repetition does nothing to stop us enjoying endless rounds of the game ourselves.

This is my BBC Future column from last week. The original is here

6 thoughts on “Why all babies love peekaboo”

  1. Cool! I’m just playing around with your thought that there’s a fundamental similarity between peekaboo and a good joke. So I’m thinking what makes the difference between a good and a bad joke?

    I don’t know about cultural differences in content, but there are loads of jokes from where I come that basically always reach one of a couple of conclusions. Most often the message is that a character in the joke is dimwitted. And sure enough, most people would say that these never get old.

    I’ve been hearing jokes about daft blondes and cops for a large part of my life. Not all of them are equally funny, of course, and my first guess is that there is a certain hypothesis about the outcome – the message of what the character in the story is like – that the listener starts with, but the context the character is immersed in varies between jokes. Therefore, there is a build-up of expectation, and when the punchline drops – BAM! Different context; nonetheless, hypothesis proven.

    I’m hypothesising that changing the context, while having the target face constant, would keep a game of peekaboo alive for a long time! 🙂

  2. It is not so much that ” things stick around even when you can’t see them ” but come in and out of existence as predicted by quantum theory. If at its basic level the universe behaves this way, then laughter, at our macro peekaboo level, is the manifestation of all scales connecting together 🙂

  3. There’s another crucial dimension to peekaboo, and it’s cousin “I’m gonna getcha!”, that both gets at a vital element of cognition and has analogues in adults – timing. (This story could probably be told without the object permanence angle at all, in fact.)

    Instant peekaboo (no delay) gets dull very quickly. There’s an intuitive mixing up of the timing, changing delays, that matters if you’re looking for best effect – in a way that’s almost identical to good comic timing.

    In particular, I’ve often thought that very popular “catchphrase comedy” in sitcoms is like adult peekaboo or “I’m gonna getcha!”. You know it’s coming, and can get all excited when you feel the phrase on its way. In a relevant comic scene it can be like watching a droplet form on a tap.

  4. The remark about timing makes me think about the fact that you cannot tickle yourself because your brain is able to predict the exact stimulation. If you cannot, you will have to laugh. Both work with getting a prediction wrong.

  5. I was reading an article about making instructional videos more fun. The author suggested adding in one surprise for each video, because “surprise sets off happy chemicals in the brain”. I thought this was an intriguing claim but no idea if it’s true.

  6. “The researchers’ interpretation for this is that the game relies on being able to predict the outcome.” –I’d be interested to learn the evolutionary reasons for why a baby laughs when he or she expects the correct outcome. That’s so intriguing.

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