The personality theory of Harvard-trained psychologist Gordon Allport rejected both behaviorism and Freud's focus on past experiences and instead looked at personality characteristics in one's present life and emphasized the individual's uniqueness. He maintained that most human behavior is motivated by functioning in a manner expressive of the self. Allport believed that each person possessed unique personal dispositions, which he called traits, and that one's central traits represented the foundation of his or her personality. Allport thought there were between five and ten central traits.

Jungian Theory

In the 1920s, Swiss psychoanalyst Carl Jung built upon Freud and Adler's work and published his own theory of psychological types. It was Jung who suggested that human behavior could be classified by how people go about such basic functions as gathering information and making decisions based on that information. He realized that some people orient themselves to the world outside themselves (extroverts) and some people orient themselves to their inner world (introverts). He then named the cognitive processes that all people engage in — thinking, feeling, sensing, and intuiting — to come up with eight types. For Jung, personality differences are the result of preferences. They emerge early and reflect both genetic and environmental influences. As preferences, there is nothing wrong with any of them — they're just different.

The Myers-Briggs Type Indicator

Around the same time that Jung was developing his ideas in the early twentieth century, Katharine Briggs was performing her own research on personality. She later set aside her work to concentrate on Jung's ideas and published a description of his theories in the New Republic in the 1920s.

Katharine Briggs collaborated with her daughter, Isabel, who also developed an interest in personality types. In 1930, Isabel published a novel, Murder Yet to Come, with characters developed using her concepts. The women thought that eventually psychology professionals would put Jung's ideas about personality types to some practical use, but it took a world war to make it happen. Spurred on by a desire to find a way to help people find jobs that suited them, Isabel Myers Briggs conducted independent research and tried a series of questions out on friends, family, and students at her children's school until she came up with sixteen distinct personality types. Each type was rated on a continuum between opposites, and each combination of four represented one of sixteen different personality types. Here are some very general characteristics.

Extrovert or Introvert

This relates to your source of energy — from without or within. Extroverts are talkers, doers, and multitaskers. They are approachable, sociable, and gregarious. They look to others for affirmation and like to get feedback. Extroverts are energy expenders. Introverts are more territorial and internal. They're reflective thinkers and listeners who like to collect data and reach conclusions alone after considering all the options. They like solitude and quiet. Introverts are energy conservers.

Senser or Intuiter

This relates to your information-gathering style. Sensing types like doing rather than thinking, tangible results, facts and figures, and reality rather than fantasy. They see the trees rather than the forest. Intuiting types are more future-oriented. They like word play, look for the interconnectedness between things, prefer generalities rather than specifics, and are more random and conceptual.

Thinker or Feeler

This relates to your decision-making function. Thinkers are calm, detached, objective, fair, logical, and scientific. For them, it's more important to be right than to be liked. They notice numbers rather than faces. Feelers consider others' feelings, accommodate others, empathize, prefer harmony to clarity, can take things personally, and seem wishy-washy to others.

Judger or Perceiver

This relates to the function you use most to relate to the world: information gathering or decision-making. Judgers are punctual and orderly. They schedule and plan, don't like surprises, and need closure. Judgers want decisions. One source estimates that 60 percent of the world's managers are Thinking Judgers. Perceivers are more easily distracted, have a wait-and-see attitude, like to leave things open-ended and keep options open, and think work should be fun. Perceivers offer opinions.

How the Types Interact

Just from these very brief descriptions, you can begin to see the conflicts and problems that might arise when opposite personalities are required to collaborate in a work setting. The good news is that no one is a “pure” type. You share some of these characteristics with all of the other types, which means that you all have things in common. Personality and behavior are also relative. You can seem more introverted in the company of a loud, aggressive extrovert than when surrounded by others who share your introverted characteristics.

MBTI Today

In 1944, the mother-daughter duo published the test known today as the Myers-Briggs Type Indicator® (MBTI). Translated into some thirty languages, the MBTI is still one of the most widely used instruments for understanding normal personality differences, which often cause misunderstanding in the workplace. The indicator has found uses in team building, hiring and firing, career development, problem-solving, goal setting, time management, and other areas. This instrument is published by CPP, Inc. and should be administered by a professional qualified to give and interpret it.

Keirsey Temperament Sorter

In the 1970s, Dr. David Keirsey built upon Galen's four temperaments and came up with a system using Artisans, Guardians, Rationalists, and Idealists. The Keirsey Temperament Sorter uses four scales to sort people into one of the four temperaments, as well as one of four character types within each temperament (Architects, Masterminds, Inventors, and Field Marshals).

Other Personality Tests

By the 1970s, there were over three dozen major, published personality inventories looking at over 300 behaviors, values, and personality concepts. Available in books and online, they vary in quality, accuracy, and usefulness.