I think they learn to do it the way we learn anything - trial and error. It just works enough and becomes a habit with a great motivator. I was jsut thinking my xab often liked to asked me if I had something wrong with my eyes. Like I would be looking right in his eyes and he would swear I was looking elsewhere. It really messed with me a lot - to the point where I would ask friends if they had noticed anything like that. (No.) . IN retrospect, this topic came up quite frequently when we were getting dangerously close to the topic of self-care or alcohol ... but then maybe it's jsut my imagination. At least now I don't have to worry about what it was.