Isabel Briggs Myers was an American writer who co-created the Myers–Briggs Type Indicator (MBTI) with her mother, Katharine Cook Briggs. The MBTI is one of the most-often used personality tests worldwide; over two million people complete the questionnaire each year. Isabel Briggs Myers typed herself as an INFP (Mediator)

The Myers–Briggs Type Indicator (MBTI) is a pseudoscientific self-report questionnaire that claims to indicate differing "psychological types". The test assigns 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".