Laughter

Laughter is a vocalized expression of amusement or relief, typically accompanied by facial movements such as smiling. It involves rapid, rhythmic contractions of the diaphragm and other respiratory muscles, and is produced by coordinated activity in brain networks including the limbic system, basal ganglia, premotor and motor cortices. Laughter includes both spontaneous and voluntary components and can be contagious within social groups.

The word laughter has deep linguistic roots in the Germanic languages and has been part of English for many centuries, reflecting a long-standing cultural recognition of the gesture. Across languages, laughter commonly functions as a social signal that communicates amusement, non-threat, and cooperation.

Laughter takes many forms, from broad hearty laughter to quiet chuckles or giggles. It is often spontaneous in response to humor, but can be elicited socially and, in some cases, used strategically in conversation. Laughter is notably contagious: hearing or seeing laughter tends to trigger similar vocalizations in others.

Socially, laughter helps bind groups, reduce tense situations, and indicate play or goodwill. It can regulate status and defuse conflict, while also serving as a marker of cultural norms around humor and expression.

Health and psychology: Laughter is linked in research to reduced stress responses, release of endorphins, and improvements in mood. Some studies report possible benefits for pain tolerance and immune function, though researchers advise cautious interpretation and note that laughter is not a substitute for medical treatment.

In culture and medicine, laughter has been studied within psychology, sociology, and anthropology. Laughter therapies and humor interventions are applied in some settings to promote well-being, though evidence for clinical efficacy varies.