Who knows you best? Not you, say psychologists

But a new article by Vazire and her colleague Erika N. Carlson reviews the research and suggests an addendum to the philosopher's edict: Ask a friend. "There are aspects of personality that others know about us that we don't know ourselves, and vice-versa," says Vazire. "To get a complete picture of a personality, you need both perspectives." The paper is published in Current Directions in Psychological Science, a journal of the Association for Psychological Science.

It's not that we know nothing about ourselves. But our understanding is obstructed by blind spots, created by our wishes, fears, and unconscious motives -- the greatest of which is the need to maintain a high (or if we're neurotic, low) self-image, research shows. Even watching ourselves on videotape does not substantially alter our perceptions -- whereas others observing the same tape easily point out traits we're unaware of.

Not surprisingly, our intimates and those who spend the most time with us know us best. But even strangers have myriad cues to who we are: clothes, musical preferences, or Facebook postings. At the same time, our nearest and dearest have reasons to distort their views. After all, a boorish spouse or bullying child says something to the other spouse or parent. "We used to collect ratings from parents -- and we've mostly stopped, because they're useless," notes Vazire. What such data would show: Everyone's own child is brilliant, beautiful, and charming.

Interestingly, people don't see the same things about themselves as others see. Anxiety-related traits, such as stage fright, are obvious to us, but not always to others. On the other hand, creativity, intelligence, or rudeness is often best perceived by others. That's not just because they manifest themselves publicly, but also because they carry a value judgment -- something that tends to affect self-judgment. But the world is not always the harsher critic. Others tend to give us higher marks for our strengths than we credit ourselves with.

Why doesn't all this information add up to better personal and mutual understanding? People are complex, social cues are many, perceptions of others are clouded by our own needs and biases, studies show. Plus, the information isn't easy to access. "It's amazing how hard it is to get direct feedback," Vazire notes, adding that she isn't advocating brutal frankness at any cost. There are good reasons for reticence.

The challenge, then, is to use such knowledge for the good. "How can we give people feedback, and how can that be used to improve self-knowledge?" Vazire asks. "And how do we use self-knowledge to help people be happier and have better relationships?"

The first answer to these questions may be the most obvious, but not the easiest to practice: Listen to others. They may know more than you do -- even about yourself.