I recently read in D. Keirsey's Please understand me that NTs really dislike public display of affection (even though I'm not sure what he exactly means by "affection").
That puzzled me a bit about an INTP friend and I happened to ask an INTX colleague about this. He said he didn't dislike affection but wasn't too good at being affectionate himself.
In my experience with this INTP, she seems pretty stiff if I give her a hug and doesn't say much when I tell her I appreciate her in a way or another, but I feel like she's uneasy about it because she doesn't know what to do rather than because she dislikes it. Often, after I've expressed my affection, she won't answer, but will say something nice later. Many days later, sometimes. Most of the times, it has to be read between the lines (very much between the lines). Also, her body language seems to speak too; a slight smile or silent, wide-opened eyes generally follow such moments. I also notice that the event that bound us as friends and led her to open up to me was a moment when I expressed my compassion to her because she was sick.
An ENTP friend told me she will often react coldly to something touching like this, but that afterwards, when she is alone, she'll think about it and feel emotional. "We are very sensitive deep inside," she said.
Sometimes, I'd really like to give my friend a hug because I'm glad to see her, but I don't dare to because of how strange she reacts to it.