Supporters of the projective approach to personality assessment are critical of the structured approach because defense mechanisms may distort responses to the closed items on structured tests.
The most notable addition of Myers and Briggs ideas to Jung's original thought is their concept that a given type's fourth letter (J or P) indicates a person's preferred extraverted function, which is the dominant function for extraverted types and the auxiliary function for introverted types.
For example, in writing about introverts with thinking dominant ...
Jung commented that the counterbalancing functions have an extraverted character." Based on Jung's original concepts, Briggs and Myers developed their own theory of psychological type, described below, on which the MBTI is based.
The MBTI takes what is called a "structured" approach to personality assessment.
Her first publications were two articles describing Jung's theory, in the journal New Republic in 1926 ("Meet Yourself Using the Personality Paint Box") and 1928 ("Up From Barbarism").
After extensively studying the work of Jung, they turned their interest in human behavior into efforts to turn the theory of psychological types to practical use.
However, although psychologist Hans Eysenck called the MBTI a moderately successful quantification of Jung's original principles as outlined in Psychological Types, he also said, "[The MBTI] creates 16 personality types which are said to be similar to Jung's theoretical concepts.
I have always found difficulties with this identification, which omits one half of Jung's theory (he had 32 types, by asserting that for every conscious combination of traits there was an opposite unconscious one).