The Evolution and psychology of self deception by William von Hippel and Robert Trivers. The paper is about fifteen pages long and after that pen peer commentaries and response by authors. From the abstract: "In this article we argue that self-deception evolved to facilitate interpersonal deception by allowing people to avoid the cues to conscious deception that might reveal deceptive intent. Self-deception has two additional advantages: It eliminates the costly cognitive load that is typically associated with deceiving, and it can minimize retribution if the deception is discovered. Beyond its role in speciﬁc acts of deception, self-deceptive self-enhancement also allows people to display more conﬁdence than is warranted,which has a host of social advantages."