Yes. It's support by research.
The first time u watch a violent movie, say a man smashes another
guy's head to bits, u may crimp...
The second time u see it u dun crimp so much...
the third...
the fourth...
...
...
and one happy day when luck is down, maybe after a couple of beers,
maybe after holding frustration and anger in the heart for too
long, and the opportunity presents itself...
There are reports thats how the nazis (or is it the north
koreans??) train their soldiers to "improve" their effectiveness in
war. Exposure to killings and violence and praises for their
leaders at a young age... everyday...brain washing.