Introduced by Optimas in 2001,[1] the JTI was developed over a 10-year period in Norway by psychologists Thor Ødegård and Hallvard E: Ringstad.
The JTI was designed to help capture individuals' preferred usage of the psychological functions identified by Carl Jung in his book Psychological Types, such as thinking vs feeling and sensing vs intuition.
[citation needed] The JTI's questions and methodology for identifying the preferred functions differs from the MBTI.
Of the two middle letters of any type, one will be the primary function with which they interact with the world, and one will be the auxiliary.
[2] Though it is relatively unknown in the United States, it has some market share in Scandinavia although the original MBTI tool is still the most commonly used.