“We don’t know what other people are thinking, and so we substitute our own thoughts about ourselves for what other people think,” Cooney explains. “We’re basically projecting what we think of our own performance, and assume that’s what other people think of us.”
People tend to be harder on themselves than they are on new acquaintances. After a conversation, you can look back on everything you said wrong and mentally correct it, or remember instances when you were funnier, kinder or more eloquent. You don’t have the same mental catalog for someone you’ve just met, so you may “take them more at face value and be much more charitable,” Cooney says.
That’s a potential problem, since underselling yourself socially may promote sadness and anxiety, or cause you to miss out on valuable personal interactions, Cooney says.