From the New York Times:

Some tales are so tall that they trip over their own improbable feats, narrative cracks and melodrama. That one-on-one playground victory over Kobe Bryant back in the day; the 34 hours in labor without painkillers; the former girlfriend or boyfriend who spoke eight languages and was a secret agent besides.

Yes, uh-huh, really. Is it closing time yet?

Yet in milder doses, self-serving exaggeration can be nearly impossible to detect, experts say, and there are several explanations.

A series of recent studies, focusing on students who inflate their grade-point average, suggests that such exaggeration is very different psychologically from other forms of truth twisting. Touching up scenes or past performances induces none of the anxiety that lying or keeping secrets does, these studies find; and embroiderers often work to live up to the enhanced self-images they project. The findings imply that some kinds of deception are aimed more at the deceiver than at the audience, and they may help in distinguishing braggarts and posers from those who are expressing personal aspirations, however clumsily

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