The mind certainly plays a big role in ticklishness, but telling exactly how much and when is a fuzzy thing.... And only makes it more interesting! As a tickler, I'd say that all the times I've been tickle-playing with a girl, they were feeling comfortable with the thing and safe and connected with me, in a sensual, if not necessarily always romantic way, and then it worked big time! Otherwise there's a barrier to overcome which prevents the body from experiencing sensations in a certain way, and that barrier is raised by a psychological factor of course... Without trust, understanding, interest, no tickling...
And then, if the tickle-game is open, there are all the little ups and downs that makes it more and less intense through time, the roller-coaster... Lots of mind-tricks played there... Your instinct can tell very well it's not just a physical connection that makes it like that!! Which is so nice!
Cheers!
justadinosaur