The Myers–Briggs Type Indicator (MBTI) is a pseudoscientific self-report questionnaire that claims to indicate differing "psychological types" (often commonly called "personality types"). The test attempts to assign a binary value to each of four categories: introversion or extraversion, sensing or intuition, thinking or feeling, and judging or perceiving. One letter from each category is taken to produce a four-letter test result representing one of sixteen possible types, such as "INFP" or "ESTJ".The test relies on the Barnum effect, flattery, and confirmation bias, leading participants to personally identify with descriptions that are somewhat desirable, vague, and widely applicable. As a psychometric indicator, the test exhibits significant deficiencies, including poor validity, poor reliability, measuring 'dichotomous' categories that are not actually independent, and not being comprehensive. Most of the research supporting the MBTI's validity has been produced by the Center for Applications of Psychological Type, an organization run by the Myers–Briggs Foundation, and published in the center's own journal, the Journal of Psychological Type (JPT), raising questions of independence, bias, and conflict of interest. Despite this, the test has been widely used in employment and educational placement. The MBTI was constructed by two Americans: Katharine Cook Briggs and her daughter Isabel Briggs Myers, who were inspired by the book Psychological Types by Swiss psychiatrist Carl Jung. Isabel Myers was particularly fascinated by the concept of introversion and she typed herself as an "INFP". However, she felt the book was too complex for the general public, and therefore she tried to organize the Jungian cognitive functions to make it more accessible. Source: Wikipedia (en)