You already know this from relationships: You're a different person with your mother than you are with your lover, your kid, your colleague, or your boss.
Each personal relationship you have pulls, like a magnet, for different sides of who you are.
With this in mind, know that in psychology, we only have a few, rather blunt tests for charting personality. The tests are like chisels rather than fine scalpels, because they capture you as the "introvert" or the "socialite" without capturing the nuance of your different selves in different social contexts.
For instance, anyone can take the famous NEO Personality Inventory and find out her general personality style. This test is indeed reliable insofar as it does mark your level of shyness or negative emotion, for instance, in contrast to other people around you. But this test only identifies your long-standing, consistent tendencies in comparison to large groups of your peers.
Today, we're building different tools that would reveal the smaller-scale shifts in personality that happen in various social contexts. We're building tools to see if some "shy girl" can become the life of the party if she's with people who put her at ease.
For instance, one new method for testing personality looks merely at language: at the words you use with various people in your life. This might seem odd at first: that the very words you choose in some casual conversation can be a magnifying glass on your personality style.
But it's true. Research has shown that the words you tend to speak reveal a lot about who you are. For instance, people who use the first person pronoun "I" more than the norm suffer depression and even commit suicide at higher rates than the norm. And people who use a high percentage of emotion-based, as opposed to intellectual, words tend to be introverts.
Psychologists have built various computer programs that analyze language for personality type. You can actually run someone's written or spoken language through these programs and in turn get a "thumbprint" that identifies a personality style. For example, these programs can reliably distinguish a speaker as male or female. They can also tell you if the person is likely to be depressed. These programs have successfully distinguished between various soldiers through letters they wrote in the 1800s, and they have identified an otherwise-anonymous author behind a book about Bill Clinton.
Last year, I did a fun study in which I ran letters by authors through one of these computer programs. For part of it, I ran Virginia Woolf's various letters--to her sister, to her lover, and to one formal acquaintance--through a computer program called LIWC. The notion of personality variation held true: Each stream of dialogue Woolf which wrote registered a radically different personality. Woolf was essentially a different woman with her sister, her lover, and her formal acquaintance.
She was more outgoing with one person, goofier with another, more reserved with the last. The most remarkable thing that I found in this study was the consistency with which Woolf maintained one "personality" with each friend. Each time she conversed with her sister, she was more emotional than she was with the formal acquaintance. Think of that: We wear different hats. And we're good at it. We are different personalities with different people around us. Do you find this to be true in your life?