Researchers have known for years that newborns begin to smile spontaneously at about 6 weeks old, and start laughing at around 4 months. But until recently, the more complex question of when and how infants learn to recognize something as funny remained an unexplored area of academic inquiry.
That is, until Dr. Gina Mireault, a developmental psychologist and professor at Johnson State College, decided to research the topic. A few years ago, she began looking for the earliest emergence of humor recognition in babies to see whether it's learned or innate behavior.
Working with colleagues from the University of Vermont, the University of New Hampshire and the University of North Carolina School of Medicine, Mireault and her team of student researchers at Johnson State enlisted the help of dozens of new parents and their babies from across Vermont to try to answer those questions.
Their findings, which were published online in September in the British Journal of Developmental Psychology, reveal that infants react to humorous situations earlier than was previously assumed.
"Long before they speak or crawl or walk, infants laugh," writes Mireault. Her research found that babies exhibit physiological signs of humor recognition as early as 4 months old and are independently capable of recognizing humor by 5 months. Interestingly, those discoveries were made using little more than a video camera and a red clown nose.
A short video of one of the study's 53 tiny test subjects reveals how those experiments were conducted. "Janie," a 6-month-old baby girl, sits in a pink high chair at her kitchen table. To her left sits her mother, to her right, an experimenter whom Janie has never met before. (Neither mother nor child are identified in the video to protect the family's privacy.)
The researcher, an undergraduate psychology student from JSC, begins the experiment by putting a red clown nose on her face, then rhythmically pressing it, each time making a high-pitched "beep!" with her mouth.
For the first round of nose touches and beeps, Janie's mother had been instructed beforehand to laugh audibly and point at the researcher. The infant, who initially looks puzzled by the stranger's odd behavior, looks back and forth between the researcher and her mom, seemingly unsure how to react. Then, after 10 beeps, the baby chuckles hesitantly, mouth agape, still looking at her mother and the stranger as though she's searching for cues.
After 45 seconds, the researcher stops. Next, she begins the second round of nose-touching and beeping, only this time Janie's mom has been instructed to watch the researcher with an emotionless face. In this round, Janie watches the nose touches and beeps more intently than before. Then, after four or five beeps, she begins smiling spontaneously, again looking at her mom and the researcher.
The big reveal comes when Janie, who is fixated on the beeping red nose, smiles independently and lets out a loud guffaw, then looks at her mom, who is still watching straight-faced. Janie immediately stops smiling, as though her mom's flat affect silently instructed her to do the same.
The clip — an excerpt of a longer video — lasts just 78 seconds. The excerpt doesn't include a second "absurd" event — the researcher wearing a book or cup as a hat while saying the word "zoop!" Nor does it include a control event, in which the experimenter does something ordinary — narrates playing with a ball or drinks from a cup — that's not intended to elicit laughter.
"I was certain that there's no way these babies were going to laugh unless their parents were laughing. But we found just the opposite," Mireault explained in a phone interview with Kids VT. "When the parents were neutral, the infants cracked up at these events. And they didn't do it with the ordinary event. They only did it with the humorous event."
If the parents laughed, Mireault continued, the babies laughed even harder and were more likely to look to their parents for confirmation. In those situations, she says, the parents' own laughter became the most salient factor in the child's humor response.
Still, Mireault wanted to press the question further: Are 6-month-olds simply picking up cues from others? To find out, Mireault repeated the experiment with 5-month-olds. At the time, she assumed the younger babies wouldn't find the nonsensical nose beeping funny on their own.
"Again," she said, "I was wrong."
Indeed, the 5-month-olds laughed spontaneously just as the 6-month-olds did. So Mireault lowered the age of her subjects even further and tried it with 4-month-olds. Again, she assumed "there's no way" infants that young could independently recognize humor.
This time, however, Mireault added another component to the experiments. Thanks to some additional grant money, all the 4-month-olds were outfitted with heart monitors to determine whether they had a physiological response to humor stimuli.
The results, Mireault said, were intriguing. Although the 4-month-olds didn't laugh at the humorous events when their parents' faces were neutral, she reported, their heart rate decreased measurably. Mireault called this finding "fascinating for lots of reasons."
First, it told her that the 4-month-olds were able to detect the humorous event as distinct from other, normal events. Second, a decelerated heart rate is typically associated with pleasurable emotions such as joy.
In this case, Mireault drew from prior research done by Dr. Stephen Porges, a research professor at the UNC School of Medicine, who asserts that a decreased heart rate preps the body for an imminent emotional response. Mireault theorizes that the infants' decelerated heart rate enables them to maintain their attention on the event and thus "primes them" to experience it as a joyful emotion — in this case, humor. By 5 months old, babies are laughing spontaneously at the nonsensical nose beeps — and their heart rate similarly decelerates, which she confirmed with follow-up studies using heart monitors.
"I love the process of discovery, that 'Eureka!' moment," Mireault said. "Whenever it happens, it's like Christmas morning."
A developmental psychologist, Mireault first became curious about the origins of humor about two decades ago, when her own kids were young. (They're now in their 20s.) At the time, she was conducting research at "the other end of the emotional spectrum" — specifically, studying how children cope with the grief of losing a parent.
Mireault recalled a moment while riding in the car with her then-3-year-old son. Mother and child often played a simile game in which she'd say something like, "I'm hotter than a turkey in the oven." Then her son would offer a reply like, "I'm hotter than a penny on the sidewalk."
At the time, she and her husband had a running inside joke. Mireault, who didn't start drinking coffee until her 30s, only drank the sugary coffee-like drinks dispensed from convenience-store machines, which her husband jokingly referred to as "mocha lattes."
One day while playing the word game, Mireault recalls her son offering this unprovoked simile: "I'm hotter than a mocha latte."
"It really shocked me, first, that he could say 'mocha latte,' but also, that he'd picked up that this was an inside joke and he knew it would make me laugh," Mireault recalled. "That's a pretty sophisticated skill ... and it planted a seed for me."
It would be years before that seed grew and bore fruit. At that time, she noted, humor wasn't considered a legitimate area of academic research. Instead, psychology focused almost exclusively on negative emotions and pathologies — depression, anxiety, phobias, trauma — and largely ignored positive emotions such as humor, joy, happiness and awe.
"If I were in grad school and said I wanted to study humor, people just would not have taken me seriously," Mireault recalled. "It had no credibility in the field."
Fast forward 10 years. In 2007, Mireault took a one-year sabbatical, during which she changed her research focus to the origins of humor. Intrigued by her son's mocha latte remark, she wondered: How early do children figure out what is funny and extract humor from their experiences?
What was known at that point? "Not much," Mireault said. In fact, she could find only one early-childhood researcher who'd even studied the question: Vasu Reddy, a professor of developmental and cultural psychology at the University of Portsmouth in the United Kingdom. But Reddy's test subjects had been at least 8 months old. Mireault decided she wanted to start younger.
She quickly discovered yet another reason why there wasn't more psychological research done previously on little babies: It's laborious work. Because they're nonverbal, experiments are inevitably time and labor intensive, requiring extensive training of research assistants.
Student researcher Brady Rainville can attest to that. He joined Mireault's research lab as a freshman in May 2014, and worked with her on several infant studies throughout his four years at Johnson State. All told, Rainville estimates that he conducted about four dozen home visits with Vermonters, who'd been recruited with help from the Vermont Genetics Network. All the babies lived within 50 miles of Johnson, and the experiments were done in their own homes, both to boost the recruitment of volunteers and to ensure the babies were in a familiar environment.
"It usually took us about 30 minutes, and then we'd be on our way," Rainville recalled. That was assuming, of course, that the babies weren't napping, eating, bathing or cranky at the time of his arrival.
"I was a little worried at first, having to work with infants," Rainville admitted. "I didn't know how they'd react to the different experiments. But it all went really well."
Now a graduate psychology student and research assistant at Long Island's Stony Brook University, Rainville said he is pursuing a research career in psychology largely due to Mireault's influence.
Mireault has since moved on from her infant humor studies to other areas of early childhood development. In a study not yet published, for example, she looked at the differences between babies' "verbal engagement" if they're transported in strollers versus backpacks. Studying infants between 7 and 11 months old, a critical time for language development, Mireault measured the frequency and duration of infant and parent vocalizations, which were harvested from their respective GoPro camera audio feeds.
For obvious reasons, backpacks differ from strollers in that the baby is closer to the adult and, as Mireault points out, the experience is more shared, not just physically and aurally but also kinesthetically.
"You can feel their physical engagement when they see something and their little limbs start thrashing," Mireault said. "That was a really fun study."
Though the results of that experiment confirmed her prediction — "the backpacks won," she said, in terms of stimulating vocalizations — her research is rarely predictable.
"Science always sends you back to the drawing board," she said. "It always questions what you think you already know."