Daniel Akst contemplates the origin of virtue:
Inhibition often begins with the sense that somebody is watching; experiments have demonstrated that simply installing a mirror makes people behave more honestly when, for example, they pick up a newspaper and are supposed to leave their money on the honor system. Mirrors also seem to diminish stereotyping, promote hard work, and discourage cheating. In one study of children, the mere presence of a mirror reduced the stealing of Halloween candy by more than 70 percent. You can think of other people as human mirrors.
Dan Ariely's post on self-control is in related territory.

