Re today's geeky science, I've noticed that I feel really good when I've recently been giving and helpful.
Regarding violence though, I overheard someone at work advocating corporal punishment for one's own children. I didn't get involved in the discussion, but I believe that use of violence sets a threshold of what it takes to modify someone's behavior. Adults that were beaten as children are probably incapable of learning to alter their behavior through words. They've been raised to believe (subconsciously) that, if no one is beating the tar out of them, their behavior is okay, regardless of verbal complaints.