The Baby Giggle: How Infant Laughing Reveals Early Cognitive Development

In this Speaking of Psychology episode, psychologist Dr. Gina Moreau discusses how infant laughter emerges in the first year, what triggers it, and what it reveals about cognitive development and social bonding. The conversation covers milestones (smiling in utero, voluntary smiles around six weeks, laughter around four months), factors that elicit giggles (novel noises, tickling), and how babies discern incongruity and intentionality. Moreau shares home-based experiments that showed six-month-olds often laugh more when caregivers stay out of the way, highlighting babies’ independent inferences about humor. The talk also touches cross-cultural questions, universal jokes like peekaboo, and future research on how social context shapes infant humor.

Introduction

In this episode of Speaking of Psychology, host Kim Mills interviews Dr. Gina Moreau, a professor of psychology at Vermont State University and director of the Infant Laughter Lab. The discussion centers on infant laughter as a window into how babies think and understand the social world during their first year of life. Moreau emphasizes that smiles begin in utero and that voluntary smiling typically emerges around six weeks, with laughter following around four months for most infants, though there is individual variation.

"laughter and smiling is a social signal primarily" - Dr. Gina Moreau

Timeline of Social Cues: From Smiles to Laughter

Moreau explains that newborns show involuntary smiles that are not under conscious control, often in sleep or in response to any stimulus. By about six weeks, babies start to smile voluntarily and become more discriminating, preferring faces and voices. Laughing typically appears around four months, with some babies earlier or later. The research highlights that laughter is not just a reflex but a social signal that communicates safety, enjoyment, and social connection, aligning with Darwin’s early ideas about infant laughter as a social tool.

"By six months, babies are acting with intention" - Dr. Gina Moreau

What Triggers Laughter and Why It Matters

Infants tend to laugh at funny noises, unexpected sounds, and playful touches like tickling. Moreau recounts an anecdote about a baby’s first laugh at a sibling’s sneeze, illustrating how novel stimuli can elicit laughter. The discussion also covers the cognitive processes behind humor, including the ability to detect incongruity and to appraise it in social contexts. Moreau notes that laughter serves a social bonding function and that babies begin to use humor to gain caregiver attention, a foundational step in social understanding.

"laughter in adults rarely follows a joke, it’s a social signal" - Dr. Gina Moreau

From Laughing with Others to Creating Humor

The interview probes when babies start trying to make others laugh. By about five months, babies begin imitating odd actions, and by six months they often act with deliberate intent, such as knocking over a tower. A classic example discussed is a viral video of a baby reacting to a parent tearing paper, illustrating violating construction as a form of humor. Moreau emphasizes that intentional humor is a dynamic process where infants test what gets a caregiver’s attention and enjoyment, gradually learning how to elicit laughter from others.

"Peekaboo is a universal crowd pleaser for infants" - Dr. Gina Moreau

"The six-month-olds were actually more likely to laugh at the event when the parents stayed out of it" - Dr. Gina Moreau

Social Context, Alone Time, and Cross-Cultural Thoughts

On whether babies smile or laugh when alone, Moreau acknowledges limited data, noting that there is some evidence that infants are less likely to smile by themselves than in the presence of a caregiver. She discusses cross-cultural considerations, arguing that laughter itself is likely not culture-bound (similar milestones across groups), while humor may be shaped by family and community norms. The episode also looks at universal social jokes such as peekaboo and tickling, and how social expectations influence what babies find funny as they age.

"laughter is a developmental trajectory that's probably not culture bound" - Dr. Gina Moreau

Research Pathways and Funding the Field

Moreau recounts her career pivot from studying early loss to infant humor, motivated by personal observation of her own child’s laughter. She describes the challenges of funding and the support she received from local NIH mechanisms, as well as the importance of framing laughter as a cognitive task—detecting incongruity and using contextual cues to interpret it—rather than as mere humor. The conversation highlights the rigorous, patient work required to track infants over time and across contexts, and how her team uses naturalistic home settings to study this phenomenon.

"laughter and smiling is a social signal primarily" - Dr. Gina Moreau

What’s Next: Incongruity, Intentionality, and the Social Brain

Looking ahead, Moreau discusses upcoming experiments exploring how infants differentiate magical incongruities from silly incongruities, and whether intentionality cues from a social agent influence infants’ laughter. She mentions collaborations with colleagues to test whether verbal cues like “mistake” versus “expected outcome” can alter infants’ interpretation of humor, aiming to clarify when babies attribute intentionality to others and how this supports social understanding.

Overall, the podcast paints a picture of infant laughter as a meaningful window into early cognition, social development, and the roots of humor that predate language.

"six-month-olds are decoding the event all by themselves as being silly" - Dr. Gina Moreau

Takeaways for Parents and Researchers

For parents, the episode underscores the value of paying attention to infants' reactions in social contexts and respecting individual differences in laughter. For researchers, Moreau highlights the potential for home-based studies, longitudinal designs, and cross-context analyses to reveal how laughter maps onto cognitive and social development in the first year of life and beyond.