We all know that guy: he won't stop talking about his wicked guitar chops, the last gig he played, and how much his music is influenced by Hendrix. Except you know for a fact that the gig he's been raving about happened over a year ago, and his playing sounds more like it was influenced by your three-year-old nephew. Why does he talk himself up so much? According to psychology, it's a form of symbolic self-completion. That is, when you feel that some part of your identity is lacking, you'll make up for it in symbolic ways.
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