Tommy is the silent guy you've noticed at the dog park. You share a comfortable familiarity with him, recognizing each other's faces and dogs. Yet, when he speaks, his words are infrequent and oddly chosen. Yesterday, as you both watched your dogs play, he commented on your dog's tail wagging with an eerie precision: 'It oscillates at precisely 45 degrees with each swing.' It struck you as odd because such exact detail was out of place in the usual banter of a dog park. Your suspicions grew when he pulled out a small notebook to record the wagging angle as if it was a matter of great importance.