How Babies Work

Is My Baby Laughing at Me or With Me?   

Laughing baby.

Through face-to-face engagement, babies learn what to laugh at and when it makes sense to laugh.

Photo by Dereje Belachew/iStockphoto/Thinkstock

An infant’s first laugh is among the most intoxicating moments in parenting. When each of my sons laughed for the first time, I felt like they’d come to life all over again. I felt like Descartes: It laughs; therefore it is. And then I reminded myself to stop calling the baby it.

If you are the sort of parent who overthinks things—and would you be reading this if you were not?—that first laugh is shadowed by a lot of questions: Why does he know that is funny? How does he even know what funny is? And is there something stuck in my teeth?

For a long time, there were no good answers to any of these questions except the latter. (There wasn’t. I checked.) Humor was conceptualized as taking place at a higher mental level, a level to which infants had not yet ascended. But that left a stubborn problem: No one had bothered to explain why babies kept laughing.

It turns out they are laughing at you. And with you. Thinking of humor in structural, analytical terms deprives us of understanding what babies can do: They may not understand the joke, but they can share in this glorious feeling of funniness. Laughter in infancy, as Vasudevi Reddy, a psychologist at University of Portsmouth in England, has argued, seems to be an “intrinsically social, even interpersonal” act.

Remarkably, even without any deeper conception of why a grown-up might find something funny, the laughter of babies has the same characteristics as adult laughter. Like us, they laugh at many different things, in many different ways, but they often laugh in the same way at the same sort of thing. When the baby in our house laughs, I almost always know why. This is what nearly all parents report, Reddy says. Laughter isn’t a mysterious sound. It seems to bubble up from a deep and early engagement in the social world. (In contrast, and very poignantly, autistic children laugh a lot—but what they are laughing about is often opaque, even to their parents.)

The very first laughs, at around 3–4 months of age, seem to be smiles that grew too big for the face: They erupt in sound. In Baby Meets World, I write about the science of smiling, the way that social smiles build on each other, crescendoing in meaning and magnitude. Laughter works in much the same way. Through face-to-face engagement, we teach our babies what to laugh at and when it makes sense to laugh. Through parent interviews and close observation of infants, Reddy has documented that this sort of social back-and-forth is the source of almost all early laughter. Even when babies laugh from tickling, or from someone blowing on their belly, it is the social stimulation—the imagonnagetchu—that sparks the laugh as much as the physical stimuli.

Babies are keenly perceptive of silliness and playfulness. “If you can distinguish the serious and the playful,” Reddy says, “at least you’re part of the way towards understanding this person understands that funny face to be funny rather than this person has just gone nuts. Or this person has an odd face.” That’s what enables babies, from an oddly early age, to be connoisseurs of slapstick.

Within several months after his first laughs, your baby wants to make you laugh—and he won’t wait until he can tell jokes. After 8 months, infants begin to display what Reddy calls clowning—they explicitly try to get someone else to laugh. They don’t have the idea first, but they instantly catch on to the idea that something might be funny. “It starts in very simple things,” Reddy says. “You’re laughing because they’re splashing you, so they splash you some more. And the things they do to make you laugh become subtler and more clever and more sophisticated.” In Reddy’s book How Infants Know Minds, she recounts the story of an 11-month-old who imitated her great-grandmother’s snoring face—and then, after everyone laughed, did it again, and then again, “deliberately, waiting for a response.” She kept doing it for days. Like any good comedian, Reddy writes, she used what works, and for her, as for many of us, the experience of getting other people to laugh was addictive. “Funniness,” Reddy concludes, “exists only in relation.”

Reddy’s work represents a challenge to the conventions of developmental psychology. She believes that the orthodox way of studying babies—carefully staged experiments in a laboratory—is counterproductive. “Psychological phenomena are fundamentally relational,” she says, and if you study babies in a laboratory, you have removed the infant from the social world. “You’re damaging the very thing that you want to study. And some of these things, especially in development, can be a bit fragile.” She argues that psychologists need to engage with infants in order to understand them. This idea is worth dwelling on because it has implications beyond the internecine disputes of academia. It suggests that parents, the people who are actually engaged with babies most of the time, have a uniquely valuable perspective. Reddy knows this well: Almost all of her research began with observations of her own children. As infants, they did things she thought they couldn’t possibly do—they teased, or clowned, or were coy. But they could do those things. And they did.

“Parents have access to experience and information which scientists would die for,” Reddy says. “You have so much data, if you’re looking for it—you know the history, you know the background, you know that this can’t be chance, you know that this is chance—whereas with experimental situations, your conclusions are much more risky. You don’t know the backgrounds of the kids; you don’t know their development. You don’t know what happened last week.”

Of course, the danger is that the parent is biased—that their observations can’t be trusted. But Reddy says the key is that parents and scientists can see different things—and they can miss different things. Their perspectives should be seen as complementary. But too often they aren’t. “We tend not to take the participants in everyday life seriously when they talk about everyday life phenomena,” Reddy says. “It’s kind of like we don’t trust people who are in this up to their elbows.”

But sometimes it is only the people who are up to their elbows in it who can interpret what’s going on. Being emotionally engaged can be what makes babies—these mysterious creatures who stubbornly refuse to explain what they’re doing—explicable.

Reddy is unorthodox, but she is not alone in valuing what parents see. This happened to come up a few weeks ago, when I spoke with the psychologist Malinda Carpenter about pointing. Carpenter is brilliant at experiment design; her insights into pointing have come from carefully calibrated experiments. (And her theory about how and when babies “know” minds is very different from Reddy’s.) She doesn’t know exactly why babies begin to point when they do, though. And I have a baby who’s about to begin pointing. This fact did not escape her. “If you have any hypothesis about why he starts pointing when he does, I’d love to hear it,” she said. I started laughing. “No,” she said, “seriously.”

I stopped laughing. I started watching.


Nicholas Day’s book on the science and history of infancy, Baby Meets World, will be published in April. His website is