It's hard to come up with a reason, but if I had to think of one, I believe my thoughts might tend to stop flowing when I'm staring directly at one thing. Meaning, I'll probably get lost staring into a person's eyes, and my conversational thoughts will cease. It's kind of like the one car accident I had... I started staring at the taillights of the car in front of me (which kind of look like eyes, in a way), and I got stuck staring there. If I look around at other things, my thoughts can continue to flow. If something grabs my eye and I feel compelled to stare too long, I might forget the more important tasks at hand. I don't know, just a thought. Sort of makes sense to me, anyway.