One type of laughter arises spontaneously from the perception of a certain class of events, while the other is used strategically in interaction to influence others or modulate one's own physiology.  -   Matthew Gervais     Quotes
One type of laughter arises spontaneously from the perception of a certain class of events, while the other is used strategically in interaction to influence others or modulate one's own physiology. Matthew Gervais