"See" the passion

Today in psychology I was sitting in the back, with my laptop open, doing some editing, because the professor does not require 100% of my attention, only about half of it. Anyways, we are doing a chapter on perception/sensory type stuff and we were talking about the eye and our professor gave us an interesting fact. If you are on a date, you can tell how much the person likes you by the dialation of their eyes. The more dialated, the more they like you, and the less dialated, well, you better wrap things up pretty quick. So, if you are on a date, you can look deeply in your date's eyes and see if you are making the right moves.