David Huron
Media Lab Europe
Dublin, Ireland, October 26, 2004
While most laughter involes some language-based humor, laughter can also be evoked by stimuli without language. In the music of Peter Schickele (alias "P.D.Q. Bach"), for example, simple sequences of pitches can cause listeners to burst out laughing. Why?
Sixty-four live recordings of Schickele's music were analyzed and 629 moments of audience laughter were identified. Each moment was classified according to the probable cause of the laughter. Excluding language-based humor and visual gags, all of the identifiable moments of laughter appear to be traceable to marked violations of expectation. Some violations are schematic in origin while others involve veridical violations of well-known musical passages. An information theoretic analysis suggests that laughter is most likely to occur when there is greater than a 100-fold difference in the first-order probability between the expected outcome and the actual outcome.
An evolutionary account is proposed that attempts to explain why the behavioral response to such violations of expectation is the distinctive punctuated exhaling ("ha-ha-ha ...") that defines laughter. Repercussions for auditory and visual design are highlighted.