David West Keirsey (/ˈkɜːrziː/; August 31, 1921 – July 30, 2013[1]) was an American psychologist, a professor emeritus at California State University, Fullerton, and the author of several books.

Both volumes of Please Understand Me contain the questionnaire for type evaluation with detailed portraits and a systematic treatment of descriptions of temperament traits and personality characteristics.

Drafted by the Army during World War II, he joined the Navy and became a Marine fighter pilot, and served in the Pacific theatre off an aircraft carrier.

Keirsey provided his own definitions of the sixteen types, and related them to the four temperaments based on his studies of five behavioral sciences: anthropology, biology, ethology, psychology, and sociology.

While Myers wrote mostly about the Jungian psychological functions, which are mental processes, Keirsey focused more on how people use words in sending messages and use tools in getting things done, which are observable actions.

[8] His main claim was that children labeled ADHD or ADD, typically, have an SP, or Artisan temperament, meaning concrete in thought and speech, and utilitarian in implementing goals.