Answer: The Tobacco Industry

The concept of Type A and Type B personality theory is so firmly embedded in American culture that it’s hard to imagine there wasn’t a time when someone would casually describe their overbearing and angry boss as “totally a Type A guy” and their own laid back personality as “completely Type B”.

The Type A/B personality theory was introduced in the 1950s by cardiologists Meyer Friedman and Ray Rosenman based on a study they conducted which they believed indicated that personality traits put people at risk for coronary heart disease. The stereotypical quick-to-anger boss was the classic Type A personality that was predisposed to heart disease and people with more laid back personalities, the Type B people, were not.

Despite the flaws in their study, it served as the impetus and foundation for the field of health psychology (wherein researchers began studying the effects of mental health on physical health). Still, it probably would serve as only a historical footnote without the average person being remotely aware of the whole Type A/B nomenclature if not for the U.S. tobacco industry.

The tobacco industry latched onto the research as evidence that it wasn’t smoking which caused coronary heart disease but the inherent personality of the smoker. Over the ensuing decades, well into the 1990s, the tobacco industry quietly underwrote dozens of studies into the Type A/B personality theory, funded workshops to teach doctors about the theories, and otherwise pushed the theory on the medical establishment and public to further distance smoking from the idea of coronary heart disease.