The Myers Briggs Type Indicator (MBTI) is a self-report questionnaire designed to make Jung's theory of psychological types understandable and useful in everyday life. The authors, Katherine Cook Briggs (1875-1968) and her daughter, Isabel Briggs Myers (1897-1980) studied and elaborated the ideas of Jung and applied them to human interaction.

After more than 50 years of research and development, the current MBTI is the most widely used instrument for understanding normal personality differences. The Kiersey test is a cut-down version of the MBTI, and as such is less robust. Kiersey also makes use of a labelling system, giving the types titles, like "Field-Marshall".

In essence, the MBTI is a tool to aid in awareness and understanding of yourself and others.

MBTI test results are described as a profile. Each person's profile is a list of four preferences.

The preferences describe four main factors of your life: (The highlighted letters show how the profiles are made up)
  • Where you direct your energy
    The Extravert/Intravert scale. The spellings here are specific and technical, and do not reflect whether a person is 'outgoing' or 'shy' but rather whether they find it more energising to be in the company of other people (Extraverts) or to be able to have their own space to focus in (Intraverts). People described as Extraverted will generally bounce new ideas off other people in the first instance, and Intraverted types will tend to think an idea through first before presenting it to others. Extraverts may find Intraverts reserved and stand-offish, Intraverts will often consider Extraverts pushy and 'loud'.

  • How you take in information,
    The Sensing/INtuitive scale. Sensing people tend to be detail oriented, whereas Intuitive types will focus on the big picture. The area of conflict on this scale is that Sensing types will tend to consider Intuitives sloppy or slapdash, Intuitives will tend to think of Sensers as nit-picking.

  • Your method of decision making
    The Thinking/Feeling scale. Thinkers make decisions based on an objective analysis of the facts to hand, Feelers on the basis of human values and the effect a decision will have on other people. Thinkers tend to find Feelers 'fluffy' and Feelers to consider Thinkers as callous.

  • How you prefer to organise your lifestyle
    The Judging/Perceiving scale. Judgers tend to prefer to make plans and take decisions quickly, Perceivers to consider all the options and to be spontaneous. Conflicts on this scale centre around the Judger's seeing Perceivers as procrastinating and disorganised and perceivers considering Judgers hasty and regimented.

The more areas of opposite preference people have, the less likely they are to get along well together.

The MBTI emphasises that no preference or combination of preferences can be judged as right or wrong - they simply describe how a person is likely to act or react.

Each scale shows a natural preference for a group of behaviours, which can be mild or extreme depending on the strength of the preference. In addition, upbringing, training and so on can enable people to learn to act more like people of the other preference - Intuitives, for example can learn to focus on detail, or Thinkers to consider the likely reactions of people as one of the 'facts' to be considered in taking a decision.

Like any psychometric instrument, the MBTI is just a tool, and should only be used to promote understanding and to identify potential areas of conflict, difficulty, or strength, not to label people - strength of preference, learned behaviours and environmental factors will mean that people with the same type will not always show the same behaviours in the same circumstances, although there will be a tendency to gravitate towards certain behaviour sets.