Laughter may be defined as the manifestation of the combination of bodily phenomena (such as the rapid deep inspiration, the forcible jerky expiration, the utterance of inarticulate sounds, the facial distortion, the shaking of the sides) that forms the instinctive expression of mirth or of a sense of something ludicrous and that can be produced by certain physical sensations, such as tickling.
There are, according to Sully,1 different kinds of laughter, which may perhaps be classified into two general types: (1) the elementary type, unaccompanied by the perception of the ludicrous or laughable, and (2) forms accompanied by an intellectual discernment of the ludicrous or laughable in the object exciting laughter.
The first type occurs mainly, though not entirely, in children. This type of laughter is seen on tickling, on joy (such as release from restraint, dismissal from school, etc.), on receiving some desired object, at play or during
PASKIND HA. EFFECT OF LAUGHTER ON MUSCLE TONE. Arch NeurPsych. 1932;28(3):623–628. doi:10.1001/archneurpsyc.1932.02240030143007
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