Ph.D. / It has become an accepted fact that Coronary Heart Disease is an epidemic of modern civilisation. Coronary Heart Disease is responsible for approximately a third of all deaths in the Western world (Fullard, 1990) and South Africa is no exception. Several risk factors contributing to the development of heart disease have been identified but the extent and exact nature of their contribution is not fully understood. Traditionally accepted risk factors that play a role in the development of Coronary Heart Disease include diet, hypertension, hypercholestrolaemia, smoking, physical inactivity, age, sex and genetic disposition. However the strongest combination of these factors has been unable to predict the majority of heart disease cases. In this regard psychological factors are steadily gaining acceptance as risk factors, one of the most important of these being the Type A behaviour pattern. The far reaching consequences of Coronary Heart Disease have necessitated investigations into methods of decreasing contact with risk factors, particularly psychological ones. The substantial success of the Recurrent Coronary Prevention Project (Friedman et al), coupled with the promising results from other intervention studies, suggests that behaviour change is a viable goal in the prevention of heart disease. Following on from the Recurrent Coronary Prevention Project, Venter (1993) and Viljoen (1993) adapted it for the South African population. Although relatively successful, it did have its flaws. Thus the motivation for redesigning this intervention addressing its shortcomings The revised intervention was administered to a group of 25 Coronary Heart Disease patients. A second group of 22 patients were subjected to the intervention utilised in the original South African Recurrent Coronary Prevention Project. A third group of 18 patients served as a waiting list control group. The results indicated that although the revised intervention produced larger changes in Type A behaviour than the original South African Recurrent Prevention Project intervention, these differences were not significant. Possible reasons for this were the measures utilised, the sample sizes and the nature of the groups themselves. However, the revised version of the SARCPP was found to be more effective in the reduction of the hostility and anger components of the behaviour pattern than the original version. In conclusion it was found that before any further research in this area be conducted, the measures utilised should be modified and the mechanisms of treatment effect be examined.

Do endocrine systems influence personality and social behavior? Although animal research has identified several hormone-behavior relationships and the mechanisms that give rise to them, much less is known about hormones and social functioning in humans. This dissertation used three large data sets to investigate whether testosterone and cortisol were related to variation in personality constructs (Study 1), leadership behaviors (Study 2), and economic decision making (Studies 3 and 4). Study 1 revealed that basal testosterone was negatively associated with conscientiousness, basal cortisol was negatively associated with extraversion but positively associated with social dominance orientation, and the interaction between testosterone and cortisol was associated with the implicit power motive. Study 2 found that the testosterone-cortisol interaction predicted leadership behaviors, and Study 3 showed that basal testosterone as well as change in cortisol predicted economic decisions in the Hawk-Dove Game. Finally, Study 4 demonstrated that aggression predicted decisions to punish unfair monetary offers in the Ultimatum and Third Party Punishment Games. Aggression was also related to women's changes in testosterone from before to after the games. Taken together, these studies provide important evidence that testosterone and cortisol are related to personality, leadership, and social decision making. More broadly, this dissertation lays the empirical foundation for further inquiry on the complex biological systems that regulate personality and social behavior.

Individual differences in autonomic nervous system responsiveness have been linked to a variety of physical disorders and personality and behavioral tendencies. The present study attempted to correlate specific personality characteristics hypothesized to be associated with either sympathetic or parasympathetic dominance based on the work of M. A. Wenger. The Clinical Analysis Questionnaire Personality Inventory, a physical disorders questionnaire, a self-report stress measure, and seven psychophysiologic tests were administered to 60 undergraduate students in an introductory psychology class at North Texas State University. The results provided limited support for the hypotheses. A skewed population with 50 of the 60 subjects achieving scores indicative of sympathetic dominance occurred. Statistical comparison (t-tests) of the CAQ personality traits, and clinical factor scores of these 50 subjects labeled sympathetic dominant with CAQ norms for college students revealed means on five personality traits and three clinical factors were significantly different for the sympathetic dominant group at the .05 or greater level of significance. These findings were interpreted as limited support for Wenger's work and for the positions of Acker and Kagan that individuals with more reactive sympathetic nervous systems tend to have difficulty binding anxiety, poor emotional controls and outlets, ambivalence about interpersonal relationships, and a need for group acceptance.