It's almost like a false alarm going off, telling the conscious functions that it needs to pay attention to this person. So then I back that feeling up with Ti+Se, looking for logical inconsistencies in their words or actions, someway to rationalize that feeling.
So Ti+Se can help me determine that a person may be lying about how they feel by looking for logical inconsistencies, but it still doesn't tell me how they're feeling, because Ti no comprende.
It really only helps me protect myself and others concerning rational things, like if someone were lying trying to manipulate me into doing something, or trying to take something from me.
On the other hand, I'm defenseless if the person in question is a feeler, and lying to manipulate the way I feel. Ti+Se can't objectify logical inconsistencies in feelings, because there is no such thing. So when it comes to feeling with another person, I have to put my utmost trust in them not to take advantage of me because I have no way to tell if you aren't being sincere, until Ti finds something, words or actions, it can objectify.
I've been burned this way before, and I think that's the biggest reason I am so protective of that part of myself, taking a long time to get close to people and only very getting close to none or a few.