Chimpanzees laugh differently if they're being tickled than if they're playing with each other, and we might be seeing something like that here, involuntary laughter, tickling laughter, being different from social laughter.
간지럼을 탈 때 다르게 웃습니다. 거기서 이런 비슷한 현상을 볼 수 있죠. 어쩔 수 없는 웃음과, 간지럼 웃음이 사회적 웃음과는 다른 것이죠.