Social-Responsibility Norm: An expected norm that people will help those in need with no expectation for future reciprocation.
This article about a 9/11 firefighter is an excellent example of the social-responsibility norm. Even though he was not supposed to come in to work that day, he rushed to work when he heard the twin towers had been hit. He had no desire to be paid back by those he helped on that day. He only wanted those people to be safe.