" Then, seemingly as an afterthought, the experimenter gave the bowl of M&M’s back to the person and said, “You’re the last subject we have today, and everyone else is gone, so these are left over. Help yourself.” The experimenter exited, leaving the participant alone to fill out the questionnaire and eat his or her fill, apparently without anyone watching or caring. But, as usual, the researchers cared very much. They had weighed the bowl beforehand, and weighed it once again after the participant left. "

― Roy F. Baumeister , Willpower: Rediscovering the Greatest Human Strength