Overview

Methods
Researching personality involves a variety of research methods. Field studies can be used to learn about people's personalities in everyday situations. Projective tests are used to learn aspects of a personality through a person's imagination. Self-report inventories are straight-forward ways to obtain personality information by asking a person to answer questions about his or her characteristics. Observe reports yield information other people's impressions of a person's personality. Finally, laboratory studies reveal information about personality in controlled situations. All of these techniques are important for gaining accurate information about personality since no one source provides completely accurate data.

Traits versus Situation
Consistency is an issue in the study of personality. In certain situations there is not always a strong correlation between a person's behavior and his or her personality traits. Consider for instance Madonna's promiscuity as a trait; Is this trait one that is consistent in all situations or is it a trait she takes on when surrounded by cameras? Most psychologists recognize that both traits and situations contribute to a person's behavior.

Factor Analysis
Factor analysis is the search for personality types based on statistical methods. The large numbers of items that describe personality are reduced to a smaller number of overlapping traits that describe a type of personality. Greek physician Hippocrates characterized human behavior in terms of four temperaments. Each of the four temperaments was associated with a different bodily fluid. The optimistic type was associated with blood, the slow and lethargic type with phlegm, the melancholic type with black bile, and the angry type with yellow bile. He believed that individual personality was determined by the amount of each of the four bodily fluids or humors. His theory influenced thought up until the Middle Ages and Renaissance. Today there is not a consensus among psychologists whether or not there are certain personality types that transcend situation.

Nomothetic Versus Idiographic
The universality of traits is also an issue in the study of personality. The nomothetic approach uses norms that are assumed to apply universally. Each personality can be described by the degree to which it has each trait. The idiographic approach is more person-centered with the belief that some traits may be irrelevant to certain people. Each individual is look at as a unique case history and not compared to group norms.

Cross-Cultural
Cross-cultural studies have been conducted to determine the effect that culture has on personality and if a different culture can produce personality types that do not exist in other cultures. Recent studies have demonstrated the similarities between personalities in different cultures which supports the notion of universality in personality.