Type A and Type B personality theory
The Type A and Type B personality theory associates two contrasting personality types with different incidence of coronary heart disease. According to the theory, people who are habitually competitive and impatient are labeled Type A, while more relaxed people are labeled Type B. While it was widely discussed in early health psychology research, the theory is now mostly considered historical and is not commonly used in modern personality psychology. Cardiologists Meyer Friedman and Ray Rosenman, who developed the theory, came to believe that Type A personalities have a significantly greater heart disease risk. Following the results of further studies and considerable controversy about the role of the tobacco industry funding of early research in this area, some reject, either partially or completely, the link between Type A personality and coronary disease. Nevertheless, this research had a significant effect on the development of the health psychology field, in which psychologists look at how an individual's mental state affects physical health.