If you're about to walk into a bar with you head, or like the top of a doorpost or smt. You'll instinctively pull back and avoid the obstacle, inches before it hurts, because your brain notice the hairs on your head moved. That's why men who have recently gone bald, often have bumps and bruises on their head. My bald colleague told me that for him, that was the hardest thing about going bald.
Or does that fractional reaction cause the brain to shift forward more than it would if they had not reacted? Could that reaction lead to worse brain injuries? Makes me wonder.
You pull away from the object touching your hair, so I don't think it would lead to worse injuries. I suppose it could set someone up better using fents and jabs.