How the brain processes trauma and why support, altruism can ease fear - Stanford

"If fear short circuits the brain’s normally logical and reasoned thinking, social support may be important in rerouting those networks back to their normal state. Which is why the selflessness and altruism we see in the wake of terror attacks is often the key to helping us to process and overcome the shock of living through them.

Szalavitz’s message of using compassion to combat fear was echoed in this TED blog post, which encourages people to “look for the helpers” as we process what happened...."

http://scopeblog.stanford.edu/2013/04/16/how-the-brain-processes-trauma-and-why-support-altruism-can-ease-fear/