Perhaps "altruistic punishment" put Obama in the White House

We all know the type: the goody-two-shoes, chasing a litterbug for a block to "return" an errant chip bag; the teacher's pet, smugly ratting out note-passers in class; the self-appointed etiquette cop, quick with a rebuke for line jumpers, crying children, and public cellphone talkers everywhere. Uptight? Quite possibly. Annoying? Almost certainly. But the urge to call attention to others' infractions is more common than we might like to admit. And, researchers are finding, the moralists among us might just be an essential ingredient in the glue that holds human societies together.

Social scientists call the behavior "altruistic punishment": the willingness to step in and enforce societal norms even if doing so carries little chance of reward and significant personal cost. Psychological theories and economic models suggest that people should make decisions about how to behave in groups based on their own best interests rather than the good of the group. In other words, taking an inconsiderate clod to task for butting into line in front of you makes perfect sense, but how to explain the person who bawls out a stranger for butting into line behind them? And yet the altruistic punishment impulse comes up time and again in daily life and psychology experiments.