Davi West Keirsey (b. August 31, 1921, Oklahoma), is an internationally renowned psychologist, a professor emeritus at California State University, Fullerton, and the author of several books. In his most popular publications Please Understand Me (1978, co-authored by Marilyn Bates) and the revised and expanded second volume Please Understand Me II (1998), he lays out a self-assessed personality questionnaire, known as the Keirsey Temperament Sorter, which links human behaviorial patterns to four temperaments and sixteen character types. 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. With a focus on conflict management and cooperation, Dr. Keirsey specialized in family and partnership counseling and the coaching of children and adults.