The Science of Tickling: Play, Pain, and Laughter
The article examines why tickling can be enjoyable or unpleasant, noting that smiles and laughter do not always indicate positive emotion. Research shows about a third of people enjoy tickling, a third have mixed feelings, and a third dislike it. The response may have evolved as a protective mechanism.
The research highlights that laughter and smiling are not reliable indicators of enjoyment. A genuine Duchenne smile, involving both mouth and eye muscles, appeared more often during comedy than tickling, while non-Duchenne smiles—used for politeness or anxiety—occurred equally across all conditions. This distinction suggests that ticklish laughter may serve a reflexive, protective function rather than expressing joy.
Laughter itself is an innate, universal behavior, emerging in infants around three months and present across species, including rats. Its rhythmic structure—short vowel-like notes repeated at fixed intervals—is consistent across humans, even in those born blind or deaf, indicating it is hardwired rather than learned. This supports the idea that tickling’s response evolved as a defense mechanism against touch.
This research could reshape how people interpret laughter and smiles in social settings, particularly among children or in playful interactions. Understanding that tickling often triggers involuntary positive signals despite negative feelings may help parents, educators, and caregivers recognize discomfort more accurately. It could also inform discussions about consent and personal boundaries, as the mismatch between outward expression and inner experience may lead to misunderstandings about what constitutes enjoyable play versus unwanted physical contact.