Institute of Advanced Studies (IAS)


IAS Laughter: Why is peekaboo the ultimate in baby comedy?

by Caspar Addyman


3 January 2021


When I ran a global survey of baby laughter in 2012, I asked parents: ‘What is the funniest game to play with your baby?’ I had responses from over twenty countries, and in every one, the clear winner was peekaboo. Since then I have been asking what’s so funny, and what explains the universal appeal of the game. The short answer is, that peekaboo gets to the heart of what human laughter really means.

In 1993, Anne Fernald and Daniela O’Neill conducted a survey of psychological and anthropological research on peekaboo.[i] They concluded that it spread far across the globe, and that variants always shared many similarities. They recorded mothers playing the game in at least seventeen different languages. The words changed, but the acoustic properties were remarkably constant. Even if you did not know the language. you would recognize the game. So would a baby. We do not know if every culture has a version of the game, or when our species first started playing it, but I guarantee that every baby in the world would like to play.

The biggest fans of peekaboo are babies under a year. In the earliest forms of the game, with babies under three or four months old, hiding is not really important. New parents will spend lots of time just staring and cooing at their little miracles. Together they discover a mutually rewarding game: mummy or daddy looming a little closer to the baby, getting clearer in its blurry vision, provokes a little smile or squeak. Peekaboo has begun. It does not yet need all the theatrics, there is no script and very few stage directions. But like all good comedy, the secret is in the timing. To keep getting the squeaks and the smiles, a parent must carefully attend to the excitement and boredom of the child. They play with the baby’s interest and expectations to get the biggest smiles and coos in return, instinctively adapting their rhythm to keep their baby entertained. Californian infancy researcher John Watson, who called this ‘the game’, found that by three months old, babies respond better when the timing is slightly unpredictable.[ii] Watson claimed the importance of the game was in the very fact that they were interacting with another person:

 ‘The Game’ is NOT important to the infant because people play it, but rather people become important to the infant because they play ‘The Game’.[iii]

Personally, I think Watson was exaggerating. Peekaboo is important and enthralling to babies not for itself, but because it grows with them.

Peekaboo is statistical, it is rule-based, it is surprising, and it adapts, so that it appeals differently to babies of different ages. It is not true that even very young babies think that you stop existing when you hide, although psychologists used to think so. In Jean Piaget’s theories, babies under one year lacked ‘object permanence’. In other words, he thought their tiny minds lacked the conceptual machinery to track things that were not there: out of sight was out of mind was out of existence. Thanks to research by Renée Baillargeon and Elizabeth Spelke, we now know babies are better at this they get credit for.[iv] You hide, and they seem to forget because of their very short attention span. If you are out of sight, their mind might fill with something else. But when you come back, they remember what game was being played. From around six months old, they anticipate your return. They are surprised and highly delighted when you do.

At first their surprise is purely statistical — i.e. a reaction to the quantitative relation of actions of the adult. But keep playing peekaboo, and the consistent pairing of expectation and reward evolves into something more. It may even become a baby’s first explicit theory about the world, her first scientific hypothesis, shaped by the eager complicity of adults who already know the rules. Each squeak of pleasure at the adult’s return marks another prediction confirmed. As American psychologist Jerome Bruner wrote, about peekaboo and the learning of rules: ‘It is hard to imagine any function for peekaboo aside from practice in the learning of rules in converting “gut play” into play with conventions’.[v] These conventions are all within the realm of social connection. Playing peekaboo, babies are learning a lot more than just that you will return. The real game for them is to learn how to have a conversation. Peekaboo is pure social interaction, stripped of all the confusing words, content, and external references. It is the simplest conversation you could have with someone. It needs to be simple, for babies, but it is still rewarding and packed with meaning. Babies learn as much from their own actions as from yours. They must react to keep you playing. Your laughs and smiles are valuable data about their behaviour. It is their first taste of a sense of agency, and it tastes good. This shows that surprise only takes us so far when trying to understand the global appeal of peekaboo.

The real magic of laughter and peekaboo is how they connect babies to other people. Babies are born social; there is nothing more fascinating to them than other people. There is nothing more enigmatic, either. The best thing about the game, for babies, is that you are playing with them. You are playing it as equals, and to play it effectively you must give them your full attention, and they find this in your eyes. Peekaboo is all about eye gaze: a potent signal that is central to our social interactions. Any adult should recognize this. Just think about a time you swapped glances with a potential romantic partner, and the rush of reward if the glance was reciprocated, became a mutual gaze. Eye contact has a powerful effect on all of us. Even newborns will turn towards faces that are looking directly at them.[vi] It is likely that the whites of our eyes have been optimized by evolution for communication. The shape and colouration of our eyes let us signal to each other who and what we are looking at. Out of eighty-eight primate species, humans are the only one with exposed, white sclera.[vii] Other primates disguise their gaze; we advertise it.

Mutual gaze is mutually rewarding. But turning gaze into a form of communication is a skill that we must master. One disarming thing about small babies is how they can hold your gaze for such a long time. Enter a staring context with a small baby, and you will usually lose. But, with time, they learn that they are seen, and what this means. To adults it happened so long ago that it has become invisible — though we still get it wrong, often with comic effect. Babies are just joining the conversation. Peekaboo and other ‘conversations’ with adults are where they learn how we construct this understanding of others through eye contact.

But why does this connection provoke laughter in babies — and, let’s not forget, also in the person playing peekaboo with them? The answer is that laughter is a social currency. It exists to be shared. Robin Dunbar hypothesizes that laughter evolved in humans to replace the grooming found in other primates.[viii] Grooming is an important investment of time, by which primates maintain their social relationships. Human social groups grew too large to support endless rounds of backscratching, and laughter is an alternative ‘honest signal’ that could be shared between larger numbers. We laugh with our friends. A study of my own confirms this, where we showed that toddlers laugh eight times as much when watching a funny cartoon in company as they do when watching it on their own.[ix]

This is the final piece of the puzzle of peekaboo. Laughter is a human innovation, that evolved so that we can connect with others. Peekaboo is the ultimate in baby laughter because it is their ultimate form of conversation and connection with the people around them. When babies laugh in peekaboo, and when you laugh back, you are sharing in a form of bonding that is central to our story as a species.

This article was adapted from Caspar’s book The Laughing Baby: The extraordinary science behind what makes babies happy (London: Unbound Publishing, 2020)

[i] Anne Fernald and Daniela K O’Neill, ‘Peekaboo across cultures: How mothers and infants play with voices, faces, and expectations’ in Parent-Child Play: Descriptions and Implications, ed. by Kevin MacDonald (New York: New York Press, 1993), pp. 259–285.

[ii] John S. Watson, ‘Smiling, Cooing and “The Game”’ in Merrill-Palmer Quarterly of Behavior and Development, 18 (1972), pp. 323–339.

[iii] John S. Watson, ‘Smiling’, p. 338.

[iv] Renée Baillargeon, ‘Innate ideas revisited for a principle of persistence in infants’ physical reasoning’ in Perspectives on Psychological Science, 3(2008), pp. 2–13.

[v] Jerome S. Bruner and V. Sherwood, ‘Peekaboo and the learning of rule structures’ in Play: Its role in development and evolution, ed. by Jerome S. Bruner, Allison Jolly and Kathy Sylva (Hammandsworth: Penguin, 1976), pp. 277–285 (p.184).

[vi] Teresa Farroni, Gergely Csibra, Francesca Simion, and Mark H. Johnson, ‘Eye contact detection in humans from birth’ in Proceedings of the National Academy of Sciences of the United States of America, 99 (2002), pp. 9602–9605.

[vii] Hiromi Kobayashi and Kazuhide Hashiya, ‘The gaze that grooms: Contribution of social factors to the evolution of primate eye morphology’ in Evolution and Human Behavior, 32(2011), pp. 157–165.

[viii] Robyn Dunbar, ‘Bridging the bonding gap: The transition from primates to humans’ in Philosophical Transactions of the Royal Society B: Biological Sciences, 367 (2012), pp. 1837–1846.

[ix] Caspar Addyman, Charlotte Fogelquist, Lenka Levakova and Sarah Rees, ‘Social Facilitation of Laughter and Smiles in Preschool Children’ in Frontiers in Psychology, 9 (2018), p. 1048.

Caspar Addyman is a psychologist and director of the InfantLab at Goldsmiths, University of London. He has investigated how babies acquire language, concepts, and their sense of time. Since 2012 he has studied how laughter helps babies bond and learn.

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