In 'Laughter Punctuates Speech: Linguistic, Social and Gender Contexts of Laughter' (Ethology, vol 95, 1993), Robert R Provine draws some fascinating conclusions from the analysis of 1,200 episodes of laughter, naturally occurring in public places at or around the University of Maryland. The first thing to note is that laughter ('a universal, stereotyped, species-typical component of the human vocabulary that is emitted almost exclusively in social settings') occurs almost exclusively at the end of a complete statement or question. Only in 0.8 percent of cases did laughter interrupt what was being said. And more often than not it was the speaker, not the audience, who would laugh.
'Most naturally occurring conversational laughter was not a consequence of structured attempts at humour,' Dr Provine reports. Indeed, typical statements preceding laughter were: 'I'll see you guys later'; 'Look, it's Andre]'; or 'Can I join you?'. 'He didn't realise he was sitting in dog shit until he put his hand down to get up' is cited as a rather atypical laughter-provoking line. He concludes: 'Most pre- laugh dialogue is like that of an interminable television situation comedy scripted by an extremely ungifted writer.'
One conclusion is that 'laughter deserves more attention than that accorded to it as a behavioural curiosity related to humour.'
For non speech-related laughter, however, we must turn to 'Pavlovian Conditioning of the Tickle Response of Human Subjects: Temporal and Delay Conditioning' (Perceptual and Motor Skills, vol 77, 1993) by B Newman, M O'Grady, C S Ryan and N S Hemmes. Following T Hoshikawa's classic 1991 paper, Effects of Attention and Expectation on Tickle Sensation, the present researchers tickled the soles of the feet of four subjects selected for ticklishness.
'Stroking motions started on the subject's heel, going up to the base of toes and back down (approximately three seconds).' The tickle response was investigated 'within the Pavlovian model' to see if subjects became conditioned to react to a gesture that precedes the tickle, rather than the tickle itself. Whereas Hoshikawa's pre-tickle gesture was the verbal stimulus 'cotyo-cotyo', the present researchers changed it to 'koochie- koochie'.
The findings were somewhat obscured by one subject called Susie being too ticklish, and confirmation among others that the response to a tickle may be suppressed by conscious effort. The etiology of ticklishness is still to be explained and further research is needed.
Finally, we should draw your attention to 'Effect of Preference for Rock Music on Magnitude-Production Scaling Behaviour in Young Adults: A Validation (Perceptual and Motor Skills, vol 77, 1993), in which Fucci, Harris, Petrosino and Banks demonstrated a clear tendency, under experimental conditions, for young adults who like rock music to play Led Zeppelin louder than those who did not.