Until then, try, in a very ISTJ fashion, to look at the functions one-by-one (obviously, read as much as possible about the functions). For example, if someone claims that Tony is an ENFJ, this means he is an extrovert. Well, IS Tony Hopkins an extrovert? Could he possibly be an extrovert? There are at least two biographies on him--I know, I've read them. What do they say about his behavior? Do your research.