Given this insecurity, the creators of “The Simpsons” took an extraordinary risk: they decided not to use a laugh track. On almost all other sitcoms, dialogue was interrupted repeatedly by crescendos of phony guffaws (or by the electronically enhanced laughter of live audiences), creating the unreal ebb and flow of sitcom conversation, in which a typical character’s initial reaction to an ostensibly humorous remark could only be to smile archly or look around while waiting for the yucks to die down.