The Myers Briggs Type Indicator is a questionnaire developed by Isabel Meyers that attempts to organize Carl Jung’s Psychological Types theory of personality development into a practical methodology.

Jung’s Theory

In his book Psychological Types, Jung introduces the idea that human personality has two types: Introversion (inwardly focused) and Extraversion (outwardly focused). His premise is that our minds do four basic mental functions: Thinking, Feeling, Intuition and Sensation.

When a mind active, it does one of two things: takes in information (Perceiving) or organizes that information (Judging). Taking in information is done with Intuition and Sensation. Organizing information is done with Thinking and Feeling. Each one of those four mental functions can be introverted or extroverted which give us eight psychological types:

– Introverted Intuition (Ni)
– Extraverted Intuition (Ne)
– Introverted Sensation (Si)
– Extraverted Sensation (Se)
– Introverted Thinking (Ti)
– Extraverted Thinking (Te)
– Introverted Feeling (Fi)
– Extraverted Feeling (Fe)

With these eight types, a person has a dominant function, a balancing inferior function, and and two auxiliary functions. According to Jung’s Type Theory, it’s the development of these functions that make up personality.

Katherine Cook Briggs (INFJ)

Katharine Briggs was born in 1875 to an academic family that valued education for women in an era when society didn’t. Her father was part of the faculty at Michigan Agricultural College (now Michigan State University) and home schooled her until she left for college at age fourteen. After getting her degree in agriculture, she worked as a teacher. This is where her interest in personality psychology began.

She researched children’s educational and social development theories but couldn’t find a comprehensive personality type theory so she began to develop her own by observing her daughter Isabel. From birth to age 13, Katharine kept a journal of Isabel’s development and tracked how different levels of feeding, play, punishment, cuddling and other factors affected Isabel development.

Katherine spent 26 years developing her own theory from raising Isabel and then using her research to write thirty-three articles on child rearing for the Ladies Home Journal. She abandoned her theory when she read Jung’s Psychological Types in 1923. Katharine was 22 when Isabel was born. She was 48 when she read Jung’s book.

She developed a way to apply Jung’s theory to children’s personalities. Three years later, she published an article in the New Republic, titled “Meet Yourself: How to Use the Personality Paint Box” to help parents type their children.

Isabel Briggs Meyers (INFP)

The MBTI as an assessment tool exists because of Isabel Meyers. Her mother Katarine was the theoritician who expanded on Jung’s theory with her own observations. It was Isabel who took her mother’s theories and developed questions that could be used as a questionnaire.

Katharine and Isabel started developing the MBTI around 1942 after the start of WW2. Using Jung’s theories, they created 4 dichotomies:

E – I: Extrovert – Introvert
S – N: Sensory – Intuitive
T – F: Thinking – Feeling
J – P: Judging – Perceiving

The dichotomies are inborn types (nature not nurture). Each person has one preferred type over the other. The combination of those four dichotomies created 16 types: ISTJ, ISFP, INTP, INTJ, ISTP, ISFP, INFP, INTP, ESTP, ESFJ, ENFP, ENTP, ESTJ, ESFJ, ENFJ, ENTJ

The object of discovering one’s MBTI was to use that type to identify how a person used Jung’s four basic mental functions: Thinking , Feeling, Intuition and Sensation. The MBTI type allowed a person to identify which of those four functions was Dominant, Auxiliary, Tertiary and Inferior. It’s the development of those four functions that’s considered our personality.

According to theory, inborn preferences E/I, S/N, T/F, J/P do not change over time. However our personality changes over time as we gain skill and experience using our Dominant, Auxiliary, Tertiary and Inferior mental functions.

Isabel Meyers added the J-P dichotomy specifically to help identify our mental functions.

From Questions to the current Form M

Using the 16 types, Isabel and Katharine identified the types of their friends and family and used them to test her questions. Isabel wrote hundreds of questions, testing and retesting to make sure the questions were answered according to type. She threw out the questions that didn’t get the answer she expected from the people she expected. She weighted the questions (0, +1, +2) where some questions counted more towards the final score than others. Eventually, she chose 172 questions that she considered most effective at sorting people into the 16 personality types. Those questions made up Form A.

She tested the questions for Form A with students at her son’s high school, friends, family and students at nearby colleges. Through her father, Lyman Briggs connections, the dean of George Washington School of Medicine allowed Meyers to test Form A to first-year undergrads. Form A was published in 1943.

From 1943 to 1963, the test was updated for better accuracy using the data that was collected. In 1962, Meyers entered into an agreement with Educational Testing Services to publish Form F. However, she was unhappy with the development and direction of the MBTI and eventually licensed it to Consulting Psychologist Press (CPP) in 1975 which published Form G. Over the Next 5 years, Isabel worked with CPP to further develop the MBTI.

Isabel died in 1980 from cancer. In INFP fashion, Isabel wrote Gifts Differing in the last year of her life from the research she had collected over her lifetime.

In the last 30 years from 1977 to present, CPP has been collecting data from MBTI results and updating the test to increase reliability and validity. Currently, CPP certified practitioners administer 2 million tests a year.

Even though Form A was created by two women with no formal education in psychology in the 1940s, the current Form M published in 1998 was created by a team of psychometricians and PhD psychologists uisng computers with data from millions of MBTI results and tested on a sample size of 3000 using IRT (Item Response Theory) methodology for scoring.