Laughing Matters

An infant’s laughter can reveal not only how babies think but also the serious reasons for this expression of joy My son was three months old when he uttered his first laugh. That he did so at a funeral was more than ironic; it was compelling. Surrounded by grieving funeral-goers, his tiny laugh was so powerful as to provoke his audience from sadness to joy—together and almost instantaneously. This observation launched my empirical investigations into the early appearance and dramatic power of that simple phenomenon: infant laughter. As a developmental psychologist, I have studied the giggles and glee of babies for nearly a decade now in my laboratory at Johnson State College in Vermont. Psychologists such as myself are intrigued by why laughter appears so early and what, if anything, it can reveal about infants. Laughter is universal. It is a hardwired response that comes online early—in the first four months of life—regardless of culture or native language. Whether a child is raised in Canada or Korea, Peru or Pakistan, her first laugh will delight her parents at about 14 to 18 weeks of age. A baby’s laugh is easily recognizable, partly because of its genuineness. Like crying, it is hard to fake and, like yawning, is contagious. Its authentic quality makes it hard for parents to ignore. Scientists, on the other hand, have only recently caught on to its significance. Of course, laughter is not exclusively an expression of amusement. In adults, it can occur in many emotional contexts, including when people are nervous, as a response to others’ laughter or more simply when in the company of other people. But why do infants laugh? It is not so much a question of what they find funny. There is no universal joke for infants. (The funeral laugh was prompted by someone’s sneeze.) Instead we must consider how infants extract humor from their environment. reveal a considerable amount about infants’ understanding of the physical and social world.