If you mean explicitly/mathematically, you can't learn that, you have to discover that (and likely get a Nobel shortly thereafter).

If you mean intuitively/qualitatively, well, I bet B&N has a shelf of books about that, though they're probably called How To Understand (or Manage) People.

It might also be that you actually mean "How can I forecast how will that girl react to X?". That's a different question altogether :-D