In my experience I can say it does not always necessarily cause laughter, hell sometimes I don't laugh, I'll just squirn/wince/groan/grunt/and whatever else. I have found that in most cases with my tickle partners (all female) that don't laugh much , (I mean even the ones that don't laugh much, they still laugh at least A Lil bit), usually it's more of a case of them being embarrassed of what they perceive as the sound of their own laughter. Yes just like some of us don't care to much for how we sound on the phone, or radio or something ( i still remember the first time i heard myself on the radio, also remember thinking how god awful i sounded) , some folks don't like too much of the way they laugh n stuff. They try hard to not emit that ugly sounding laugh of theirs, and it's gotta come out in some way shape or format, so usually it's in the form of squigglin/squirmin/moaning/grunting/squealing or whatever else.....what I've ascertained in my humble experience.