The first theory of DISC was from psychologist William Moulton Marston in his 1928 book titled, emotions of normal people. His definition of DISC was Dominance, Inducement, Submission and Compliance. However, Marston never patented his findings. The DISC model was first published as a psychological test in 1956 by someone else - an industrial psychologist named Walter V Clarke - but he used a different acronym (ASSA) which stood for Aggressive, Socialble, Stable and Avoidant. Today, the acronym DISC is more diplomatic to show that there are no right or wrong behaviour traits.