Before babies have the words to tell us what they're thinking, they can laugh. Infant giggles are undeniably adorable. They're one of babyhood's most joyful milestones. And it turns out these joyful moments have a serious side too. For scientists, infant laughter can provide a window into understanding how babies' minds develop during their first year of life. So when do babies start to laugh and why? What do they find funny? What do some babies laugh at almost anything while others have a more serious temperament? When do babies start trying to make other people laugh? And what can this progression tell us about babies' cognitive development and how they experience the world? Welcome to Speaking of Psychology, the flagship podcast of the American Psychological Association that examines the links between psychological science and everyday life. I'm Kim Mills. My guest today is Dr. Gina Moro, a professor of psychology at Vermont State University where she directs the infant laughter lab. She studies how babies discover what is funny, how they perceive, interpret and respond to the unexpected in social contexts, revealing the earliest foundations of humor and social understanding. Her research has been funded by the National Science Foundation and the National Institutes of Health and covered by media outlets including CNN.com, NBC Nightly News and PBS's Nova Science Now. She recently wrote an op-ed for The New York Times called The Evolutionary Brilliance of the Baby Giggle. Dr. Moro, thank you for joining me today. Thank you so much for having me. Let's start with the basics. How early do babies start to smile and laugh and does smiling come first or do both actions emerge around the same time? While smiling comes first, babies actually smile in utero. So it's an involuntary smile and most parents will observe this smile when their babies are brand new to the world. But these smiles are involuntary. They're not under the infant's control. They smile in their sleep. They smile indiscriminately at any kind of stimulus. And it's not until about six weeks, but babies vary quite a bit. So some babies will start to voluntarily smile earlier than that. But roughly about six weeks, babies can voluntarily smile. So they become much more discriminating. They like faces, for example. They might smile at the dog's face or at a lick from the dog or at mom or dad's voice or something like that. So six weeks, we see voluntary smiling. And then laughter for most babies who are on a typical developmental trajectory is at about four months. Some babies a little sooner than that and some babies a little later. And what are the earliest things that make babies laugh? So typically, babies will respond to funny noises, unexpected noises, and they also respond to touch. So tickling, for example. You know, my son's first laugh was at my brother's sneeze, which is a shocking sneeze. So it is a sneeze that will get your attention. And so it might be something like that. Hearing a rooster crow or something that's really novel that they've never heard before, that will often do it for a brand new laughter. Now, in adults, we know that laughter is one way that we bond with other people. What purpose does laughter serve in babies? Is it the same for babies as it is for adults? We think so. I mean, I think one of the surprising things about laughter and smiling is that laughter in particular is that there's a really good research primarily initiated by Robert Provine at the University of Maryland, showing that laughter in adults rarely follows a joke. So it's not that we don't laugh at jokes, we do. But most of our laughter is in response to these benign social remarks like, oh, I'm going to be late. Ha, ha, ha. Or, oh, I parked the car funny. Ha, ha, ha. Or something like that. Like, I can't find my keys. Ha, ha, ha. So these are odd things that we laugh at. But in keeping with Darwin's idea, Darwin was the first one to really write about infant laughter in his own child. The idea is that laughter and smiling is a social signal primarily. It serves a social purpose, first and foremost. We do share these kinds of signals with other mammals. So it does seem to communicate, I trust you. We are safe together. I enjoy your company. I like you. I like those kinds of things. Understanding a joke is a cognitive exercise. You have to get why a joke is funny to laugh at it. But in your work, you found that infants as young as four or five months can distinguish between ordinary and incongruous events, and they find incongruous things funny. Tell us about that work. Yeah, this still knocks my socks off. I mean, I think this is what I love about science is, science is so surprising whether you get the hypothesis right or not. There's always something there to unpack. So we really thought that this was kind of an open and shut case when we were trying to figure out why do babies or how do they figure out what's funny. And typically what happens is, parents are giving lots of cues when there are these absurd things going on. So the parent blows a raspberry on the baby's tummy and laughs and smiles in response. They pull their socks off and wave them around and laugh and smile while they're doing that. And we thought, well, this is what's going on. So we set up a little comedy club for babies in their homes, and we showed babies two different types of absurd events. One was taking a foam ball and putting it on the research assistant's nose, and the research assistant would poke their nose with their finger and say, beep, beep, beep, all with a straight face. The control event was the same foam ball that the researchers just passed back and forth from hand to hand while they said a script. Like this is a ball. It's red. It's squishy, something like that. And then we had parents do one of two things. So the parents never interacted with the infant. The infant could see the parent and the research assistant. And the infants were really poised so they could see the parent's reaction to the event. And so when the odd event was shown, like the ball is the clown nose, parents were instructed to either point and laugh at the clown nose or to simply look at it, to not laugh or smile, just have a neutral face. And we really thought these six-month-olds would just find it funny when the parents found it funny, but that's not what we observed. So the six-month-olds were much more sophisticated than we thought. This is often the case when you're studying babies, and parents know this, grandparents know this. Babies will surprise you at their level of sophistication. So the six-month-olds were actually more likely to laugh at the event when the parents stayed out of it. So they were decoding this event all by themselves as being silly. And it's still surprising to me that this is the case. Now, when do babies start trying to be funny themselves to produce humor rather than just laugh at something? And what does that say about their cognitive development at that point? It's such a great question. And what this question really gets at is intentionality. So when is it that babies intend to make somebody else laugh? And that can be a really tricky thing to get out experimentally. We also know that babies will accidentally make people laugh. So for example, babies don't have a lot of good physical control over their bodies in the first few months. So at three months or three and a half months, they might make a strange face or maybe their eyes are going in two different directions or something like that. It's not their fault. They just aren't myelinated yet. So parents might laugh at these odd things that babies are doing which aren't under infant's control. We are too conservative as scientists to attribute intentionality to that. What we do know, though, is that by about five months, babies do start to imitate odd actions. So for example, if parents are just blowing raspberries, the babies will typically have enough voluntary control to participate in that and to maybe imitate that as well. We've seen infants in our studies do this. And parents, of course, will laugh at that. So I think it's a very dynamic process where babies figure out what gets the caregiver's attention and keeps it and is fun and enjoyable. Certainly by six months, babies are acting with intention. They will knock over a sibling's tower on purpose, for example. There's a great viral video on YouTube of a dad tearing paper and the baby sitting on the couch seems to be about six or seven months old and the dad tears the paper and the baby just cracks up and just can't contain themselves. And this is a good example of what we call violating construction. So this paper is supposed to be in a certain form and the dad is destroying it. And we see infants start doing that at about six months of age where they will violate a construction pop a bubble on purpose, for example, something like that. Will babies smile or laugh when they're alone? I think we know that adults don't tend to do this. That's a great question. There's just a little bit of research on this. There's just a little research in this area. So if anyone out there is thinking about a dissertation topic, lick me up. There is some work by Marianne LeFrance with 10-month-olds. And I don't remember exactly the experimental setup, but she did observe that infants were much less likely to smile when they were by themselves than when there was a caregiver. And it doesn't take much. With babies that are about three months of age, our first study found that about 50% of three-month-olds would smile simply in response to a caregiver's smile. But by six months, only about 5% of babies would do that. So smiling alone is not quite enough. There is this cognitive piece that is involved a little bit later. But you're asking a really insightful question, which is that, yes, smiling does seem to be this social signal so that if you're by yourself, you might as well reserve your smiling. What if a baby doesn't start laughing around five months or so? What does that indicate? And when should a parent be concerned? Yeah, it's a really good question. I'm not a pediatrician or a clinician, so I'm always a little bit hesitant. I get a lot of emails from parents who are worried. And I tend to think that parents should and other caregivers should go on their gut instinct here. They have the best experience with their baby. They have the best frame of reference for what their infant does. Do they make eye contact, for example? Do they like to be snuggled? Are they curious and investigating the environment? So is this lack of laughter part of a bigger picture, or is it just this thing where it takes more to get them to laugh? We've done one study looking at laughter at six months as a predictor of attachment at one year. And so this was a longitudinal study. And again, we were really surprised at the findings. We actually found that babies who had a higher threshold to laughing, so they weren't big laughers. They weren't laughing with the frequency of some of their counterparts in our sample. They actually had a higher quality of attachment at 12 months. And it's very counterintuitive. But we think what was happening is that parents of these more sober babies had to work harder to get them to smile and to engage with them, and that this actually paid dividends for the babies in terms of attachment. Do you follow babies very far into their lives? I mean, like, do you know if you're looking at a baby at four or five months, do you ever see that same child at five and discover whether, you know, this kid's a stand-up comedian. He was very funny as a baby. We don't. It's hard enough to follow them for a couple of months. Babies are actually very hard to study because parents are so busy and babies often are cutting teeth or they get sick or they just don't feel like participating in your study the day you need them to laugh. They're in a terrible mood. So we do well to follow them. You know, we've done only one study where we followed them from three months to 12 months, and it was incredibly laborious. We're glad we did it. But yet right now we're just doing some point in time studies. We have done some from six to 12 months. Usually I don't go past that point. I have a great colleague at the University of Bristol in the UK who studies joke telling and toddlers. So she sort of picks up where I left off or vice versa. Are there cultural differences or do all babies manifest humor at about the same time developmentally and in response to the same stimuli? We don't have great cross-cultural data. I mean, I tend to think about laughter and humor are separate. So laughter, I think we can think of as following a developmental trajectory that's probably not culture bound. It's kind of like walking and talking that these milestones tend to be hit at about the same ages unless there's some extreme intervention on part of the culture. There's a, for example, a culture where they use cradle boarding and babies are strapped to a cradle board while their parents work in the fields. And those babies are a little later to walk, but as soon as they're out of the cradle board, they catch right up with their peers. So I think we can think of laughter as being not culture bound. Humor might be and that might also include the culture of the family, not just the culture of the country or the nation. So I think about the type of things that kids are allowed to laugh at, for example, in my own family. We tend to say we have very dark humor and our kids who are now adults had and still have very dark humor. And we saw that from them at very early ages. And we even wondered as parents, we're both psychologists, is that okay? But we decided we had other things to worry about. So I think that humor specifically is probably is culture bound and the culture can be a microculture of the family or a community, for example. We're going to take a short break. When we get back, we'll talk about whether there are any surefire jokes that make all babies laugh. Is there any one thing that all babies find funny, like peekaboo? Well, I never like to say all, but I think peekaboo is a great guess. If you are traveling on public transportation and there's an infant whose parent really needs a break, then I think peekaboo is a great go to. And babies in the four to six month old age range, our pediatrician used to say they have a social agenda. I love that description that they are so engaged by other people for the most part, they might find almost anything you offer them to be worthy of a smile, if not a laugh. Peekaboo is great. Tickling tends to be a universal crowd pleaser for infants, certainly infants under about seven or eight months. They like it. We do know that as babies get older, for example, even by six months, babies will find peekaboo entertaining for a very short period of time. And then you need to work harder for it to keep them engaged. So they start doing something fascinating at that point, which is something called polite laughter, which is also sometimes referred to as fake laughter. So I don't like fake because it sounds manipulative, but that is what it's called. In the literature. So this just means that adults do this, too. If we, you know, somebody tells a joke and we think it's kind of funny, we might go, you know, something like that, where we want to communicate like we really like you and we really want to stay in this conversation with you, but you got to do better. Six months old can do that. Yeah. What about other mammals, other mammals, smile and laugh like human babies? Yeah, they do. And this is so amazing. Particularly juveniles. So most of this work, there's some good work in comparative psychology, looking at this and other non-human primates. But I think some of the most fascinating work was by Yac Panksep, who just passed away within the last couple of years. He was a neuroscientist and he studied rats and found kind of by accident that when you tickle rats, he studied emotions. So there was a reason for him to be doing this. When you tickle rats, they actually chirp and they chirp at a very high frequency. So it's not available to the human ear. You have to have specialized equipment to hear it. But their chirping is at a similar cadence to human laughter. For listeners who have dogs, dogs are a great example. If you listen to dogs when they're playing, they do what's called play panting. And it sounds kind of like a chimp. So they go, they only do this on the exhale. But anyway, dogs do this and other mammals do as well. So again, this kind of gives some real leverage to Darwin's argument. What Panksep discovered, he may not be the first to discover this, but I can credit it to him with confidence, is that other mammals have all the same brain structures of the limbic system, which we have. So all mammals share those same structures and not suggest that emotion, joy, sadness, some of the primary emotions did not just bubble up in humans, that these have been there and they're part of our evolutionary ancestry. So we're not necessarily projecting onto our pets that they're laughing. They may actually be laughing in their own way. I live with a very funny dog. Yeah, I think, you know, we have to be careful about that, right? That we're not just projecting. Although Panksep actually made the argument that we should, that to try to remove ourselves from the other mammalian experience is really inhumane and it's ascientific or non-scientific, that to understand other emotional experience, we should try to relate it to our own experience. This was not necessarily a popular argument. It was a very controversial argument to make, but it's an interesting one to entertain. So how did you get interested in studying humor in babies? And has it been challenging for you? I mean, you've got a lab, but getting funding for the kind of research you do, which some people might say is frivolous. Yeah, absolutely. So for about 15 years, I studied loss. I studied early loss in childhood. And at the beginning of that line of research, I had a baby and I had never, my son's my first born and I had never even changed a diaper. It's a shock that they let me leave the hospital with him. We had no experience. But anyway, it was so I was really, you know, having this front seat experience with him as a mom. And he started laughing to my brother's sneeze when he was about three and a half months old. And, you know, when you're a psychologist, you just can't help but observe behavior. It's just kind of an occupational hazard. And I remember being so shocked that he was laughing and really amused and entertained by this. And I thought, what is that? Why? Why do why do infants laugh? I knew that they laughed. I just never asked the question why. So it was about he was 13 when I took a sabbatical and switched my research focus and went and studied in the UK with my colleague now, good friend, Vasu, ready. And it was at that point I had to apply for funding. So I was really worried that this would be seen as a frivolous line of research. I applied for some funding within my state in Vermont. We have this nice mechanism that is through an NIH inbury grant so that little colleges don't have to compete with the big colleges for money. So I got a little grant and collected some data with my students. And then I went to a big infancy conference to present it. And I was very, very nervous. And the very first response I got, I was just doing a post-doc. It was some preliminary data. Another scientist approached me and she said, Oh, my gosh, you study laughing. Oh, I study crying. She was she was so filled with regret. And, you know, she really she just gave me this sense of real relief and validation that, OK, it's going to be OK. She was fascinated in the study. So from that point on, I was never concerned. And the work has been wonderfully received everywhere that I've presented it or my students have presented it. In terms of getting funding, I will say that I don't use the words humor. I don't. We do say that we measure laughter. But, you know, it's what we're really studying was something you were getting at earlier on in this conversation, which is that we're studying something cognitive here. So we're interested in this cognitive skill and whether or not infants have it. And that is really their ability to detect incongruity, which means an unusual or unexpected event, and to appraise it. And what are they using in their environment to appraise it? So that's the language that we use in funding. So what are you studying now? What are the big questions that you're still trying to answer? Yeah, so we just finished up a study. We have a manuscript in revision. Fingers crossed that that's all done pretty soon. One of the questions that I was really intrigued by was how infants differentiate different types of incongruities. So there's a big body of literature that looks at magical incongruities. These are impossible events like a ball floating in the air, for example, or an object turning into another object. So we call them magical because these are kind of impossible events. And there's a whole wonderful body of literature that shows that starting at about three and a half months of age, babies stare at those events when you compare those to control events. So they're really captivated by them. And then in my line of research, which is like four people doing this work, we show babies incongruities, but they're silly incongruities. So the question that we've just gone after is how do babies distinguish these types of events? You know, can they? And what we did in this last study was we presented babies with magical incongruities, but we put them in different contexts. In the magic literature, babies just see the events. There's they don't see a person. They just see hands or they see a theater screen where the events are unfolding in an asocial context. So all we did was take two magic tricks and we put them in a social context. We had a magician perform the events. They did not interact with the babies. And babies were much more likely to smile at these events. They actually did not look longer at these events, which contradicts this other body of literature. But it's one study. It's in a naturalistic context needs to be replicated. But it is interesting to think that, you know, infants are really, really picking on the social environment and that they're deriving meaning about events just based on the presence of another person. And it could be it could be that they're attributing intentionality, like, oh, that person meant to do that. And that lets them resolve the incongruity, which is like getting the punchline, like, oh, that's what you meant. That's funny, you know. So I'm just working on our next study with a brilliant colleague, John Lane at Vanderbilt. He's been a consultant on this current study. And we're thinking about putting this question of intentionality really to the test and showing infants magic tricks where the magician will use a technique that, again, Elena Hoika at the UK Bristol University has used. Where infants hear one of two verbal cues, they either hear the magician say, oh, like, this was a mistake or, haha, like, I meant to do that. And seeing if infants can use those cues to understand the intentionality of the magician in one condition and whether or not they'll be more likely to laugh in response or smile. So Elena has done something like that with older toddlers. So we'd really be scaling it back for babies. Well, Dr. Maro, I want to thank you for joining me today. This was really a lot of fun and got me laughing too. Oh, great, great. Well, that's always a great success. Thank you so much for your interest. I really appreciate it. You can find previous episodes of Speaking of Psychology on our website at SpeakingofPsychology.org or on Apple, Spotify, YouTube or wherever you get your podcasts. And if you like what you've heard, please subscribe. And leave a review. If you have comments or ideas for future episodes, you can email us at SpeakingofPsychology.org. Speaking of psychology is produced by Lee Weinerman. Thank you for listening. For the American Psychological Association, I'm Kim Mills.
