Ronald Melzack (July 19, 1929 – December 22, 2019) was a Canadian psychologist and professor of psychology at McGill University. In 1965, he and Patrick David Wall revolutionized pain research by introducing the gate control theory of pain. In 1968, Melzack published an extension of the gate control theory, in which he asserted that pain is subjective and multidimensional because several parts of the brain contribute to it at the same time. During the mid-1970s, he developed the McGill Pain Questionnaire and became a founding member of the International Association for the Study of Pain. He also became the founding editor of "Wall & Melzack's Textbook of Pain"