MotoH said:
What the hell drives people to go shooting up schools? Is it to get their 15 minutes of fame or what?
I can tell you that from the formal psychological percpective if you like. I realize that = slumming for physicists

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Imagine you want to succeed in life (maybe not a stretch), but you constantly fall short of your and other's expectations. Feeling inadequate you either isolate yourself and become more depressed (over years/decades), or you become VERY angry (rage really) and the challenges of life become focused on a set of events or people.
At some point in your life, a crisis occurs, which could be existential, or financial (or in the case of amy bishop, having tenure finally out of your grasp). Now, most people would:
1.) Buy a porsche.
2.) Cheat on their spouse.
3.) Both.
4.) Find religion
5.) Golf (ta ta TUM!)
6.) Get help, cry, etc.
If however you never developed meaningful coping skills, you suddenly feel UTTERLY overwhelmed and out of control. This is frankly unbearable for a human being, but since options 1-6 (and others ofcourse) are not on the table, and rage is RIGHT there (or hopelessness) the following occurs.
Obsession: This has already happened, and so the target is there and waiting, always. Who is less important than WHAT.
A Message: Like a child hitting, they're saying "SEE HOW BAD I FEEL?! See how ANGRY I can be?"
Significance: We ARE talking about these people. Say what we want, they have an impact, and they know it. That's life
That's usually a part, but the dual driving force is THIS:
1.) No hope. I want to die.
2.) I am so full of rage, I will hurt and hurt until someone puts me down
It's simple, sad, and very human. It is the victory of the limbic system over the frontal lobe, and it's evidence of misery both past, and created by these events.
The sad thing is that instead of using these as models for less extreme early violent criminal behaviour, and helping those kids or young wo/men... we focus on the few people who really DO snap this way, and ignore those people who constantly act out by just shutting them away.
*sigh*