And through all the years, many, including many personality and social psychologists, have believed the individual is the best judge of his or her own personality.
Vazire's study is published in the February 2010 issue of the Journal of Personality and Social Psychology.
Personality is composed of the underlying traits that drive behavior, Vazire says. The model she developed is called the self-other knowledge asymmetry (SOKA) model. To test it, she called upon 165 volunteers who were given a number of different tasks.
To obtain an objective measure of behavior, they took an IQ test; they all participated in a leaderless group discussion to see who emerged as the take-charge individual; and they took a Trier social stress test, in which trained experimenters with faux stern demeanors filmed participants in a narrow, cramped room, as they gave a two-minute public speaking exhibition on the topic of what I like and don't like about my body — a sweat-inducer for many. Each participant also graded group members and him or herself on a 40-trait personality rating form.
Vazire's model correctly predicted that self ratings would be more accurate for internal things, such as thoughts, feelings, sadness and anxiety, for example, than the ratings of friends and strangers.
The self is better at judging friends' intelligence than its own "because it's not that threatening to us to admit that our friends aren't brilliant, but it's more threatening to admit to ourselves that we're not brilliant," she says.