Duncan is best known for his contributions in the field of
drug abuse, which have often been highly controversial. In 1974, he and
Edward Khantzian of
Harvard Medical School, in separate publications, proposed what has come to be known as the
self-medication hypothesis of addiction. Both authors proposed that addiction arose out of the use of drugs to medicate a preexisting disorder or problem. Duncan's version of the hypothesis is distinguished by its identification of addiction with
negative reinforcement. Duncan argued that all of the characteristics commonly cited as typical of
addiction, such as persistence in the face of negative consequences and high probability of relapse, are all common in any negatively reinforced behaviors. He also has argued that
harm reduction approaches to addictions, HIV or other public health concerns are instances of the traditional
public health practice of tertiary
prevention—prevention of deaths or disability that might otherwise occur due to a health problem. Duncan first applied this approach in his work with adolescent drug abusers in Houston, Texas in the early 1970s and soon afterward with heroin addicts. In 1983 he and
Robert S. Gold published an argument for this approach, which they then called "cultivating drug use", using the word cultivating in its sense of the elimination of weeds and promotion of healthy growth. Duncan has also been involved in the development of
computer assisted learning and particularly computer based health education. His leadership in this field began at the
State University of New York at Brockport, where he collaborated with Robert S. Gold in developing the first course on computers in health education offered at any college. In 1980, he and Gold published two papers that spurred interest in the use of computers in health education. One of these papers was the first publication to suggest that microprocessors, as
personal computers were then known, could be preferable to
mainframe terminals for use in computer assisted learning. A few years later, Duncan and Gold, then at
Southern Illinois University, taught the nation's first college-level course on PC-based methods in education. Three years later, Duncan argued for the value of portable computers, which were just being introduced, for educational and data collection applications. He also pioneered the use of
roleplaying games on the PC and internet for use in both health education and data collection. == Career ==