The Myers-Briggs Type Indicator, or MBTI, is a popular personality test that claims to differentiate 16 distinct personality types, distinguishing the extroverts from the introverts, the sensing from the intuitive, the thinkers from the feelers, and the judgers from the perceivers. Though widely criticized by professional psychologists as pseudoscience, the MBTI is still beloved by HR departments and career counselors around the globe. Here’s some background. Katharine Cook (married name Briggs) was born in 1875 and went to college at the age of 14, where she studied agriculture and graduated first in her class. While Briggs was expected to live as a traditional homemaker after receiving her diploma, her desire to learn remained unquenchable. She’d pour much of her energy into educating her daughter, Isabel—who, as an adult, would later help her develop the famous test. Briggs was fascinated with the “correct” way to raise a child. She began studying developmental psychology, largely kept her daughter out of traditional school, and kept a detailed diary of Isabel’s developmental progress. (Briggs referred to her living room a “cosmic laboratory of baby training.”) I...