The aim of the study was to investigate the association between Type A personality and CHD. Over 3000 men aged between 39 and 59 took part in the study. They were assessed over eight and a half years. All the participants were healthy at the start of the study. The first part of the study involved categorising the participants into high-stressed personality (Type A) and non-stressed (Type B). This was done using structured interviews. However, the researchers were not only interested in participants’ responses to specific questions, such as “How do you react when you have to wait in a queue?”, but also in how they behaved during the interview. The whole experiment procedure was set up in such a way as to antagonise the participants. These behaviours counted for 75% of the overall score that determined their personality type, while answers to the questionnaire were only worth 25%.
Nearly twice of the Type A participants developed CHD during the duration of the study. When physiological measures were assessed they were found to have significantly higher levels of adrenaline, noradrenaline and cholesterol. Friedman and Rosenman then concluded that there is a close relationship between Type A personality and CHD, which led to another conclusion that there is also a close relationship between Type A behaviour and the likelihood of suffering from stress.
One of the strengths of this research study is the large number of participants. In addition, the study was assessed over a period of eight and a half years, making it a longitudinal study.
However, there were a number of problems with the study. The researchers used the correlation method, with which we cannot assume a causal relationship by saying “Type A personality has caused CHD”. It could be due to genetic reasons, or the individual had been going through intensive stressful life events by the time the physiological measures were assessed. Moreover, all the participants were men. This has risen up a question about gender differences - can the findings be generalised to women? If they can, how far would that be? In addition, the study used interviews. Even if the interviews were highly structured, they were always to be criticised of being subjective. It was absolutely impossible for the interviewer to be consistent with every participant, and two interviewers could never act the same as each other. This, as well as the fact that the study was laboratory-based, could lead to the lack of ecological validity, due to factors such as Demand Characteristics and Researcher Effects. Furthermore, Type A personality is a collection of behaviours. The concept was not specific enough to determine which aspects of Type A are associated with CHD. In fact, Rosenman himself has recently admitted that Type A is very difficult to define. He suggested that competitiveness may lead to other characteristics such as impatience and hostility. Since the original work, many studies have looked at the relationship between type A behaviour and CHD. Some of these were retrospective and some prospective. Significant correlations have been found, but these were never very high, and many negative findings have been reported. Even the value of the Type A concept has been questioned (Evans 1990). Further work in this field has suggested that Type A personality has a number of less obvious underlying traits. Type A people are often over-controlling and possess a strong sense of duty (Totman 1990). They are high achievers and so must be very committed. Therefore they would reasonably be expected to show high levels of commitment and control.
Despite the fact that Type A behaviour seems to be a risk for stress-related illness, many Type A individuals live quite happily with their pressured and competitive lives. So, along with factors that make them vulnerable to stress, Type A personalilty may also score highly on protective factors such as commitment and control.
