"The practice of pain rehabilitation increasingly developed during the twentieth century by evolving medical specialties of physical medicine and rehabiltitation, anesthesia, psychiatry, and occupational medicine. John Bonica, one of the fathers of pain medicine, championed a more comprehensive biopsychosocial multidisciplinary approach in the United States in 1947. This approach expanded to include a team of clinicians at the University of Washington in the 1960s. Bonica's collaboration with Wilbert Fordyce, a psychologist, incorporated operant conditioning and other behavioral approaches with more specialized, structured, and in-patient multi-week programs. In the 1980s, John Loeser formalized a more structured program at the University of Washington. This 3-week long, daily program became a model for interdisciplinary treatment."