| Summary: | The acute stress response is an adaptive and necessary function which, when activated under appropriate conditions, promotes survival. However, studies have demonstrated that chronic over-activation of the systems that regulate the stress response leads to the dysregulation of the hormonal mediators, which can, subsequently, result in deleterious health outcomes. Whilst the psychobiological response to acute stressors has been explored extensively, literature assessing the anticipatory and recovery windows surrounding stressor exposure is currently in its infancy. It has been observed that the anticipatory period prior to exposure to a stressor can prolong the activation of the stress response; however less is known of the effects of delayed recovery following stress exposure. The present thesis addressed the question of whether anticipatory patterns differ between a naturalistic and laboratory stressor, by firstly developing an ecological and easily administered socially evaluative stressor paradigm, and using this stressor as a tool for a) assessing the psychobiological response to the novel stressor and b) assessing the anticipatory and recovery period following this stressor, through the collection of psychobiological data over four days (the day prior to exposure, the day of exposure, the day after and on a control day). A similar sampling protocol was applied to assess the anticipation period preceding a naturalistic stressor (skydiving). Individual differences, which may potentially exacerbate or buffer the negative effects of stress, were also explored within the context of these stressors. In addition to assessing anticipation of forthcoming stressful events, following recent suggestions that forthcoming positive activities may also elicit similar patterns of anticipatory responses, the current thesis also addressed the question of whether these anticipatory responses may represent a reaction to memory recall for an upcoming task, and not exclusively a response experienced prior to a stressful event. This was addressed by assessing the anticipatory period prior to the requirement to remember to complete a simple task in order to receive a reward. The findings indicate that the developed stressor successfully elicited a stress response, and was anticipated to be a forthcoming demanding situation. State anxiety was greater on the day of planned stressor exposure, as was stress and worry about the event. In the skydiving study, those who knew they would complete a skydive that day secreted greater levels of cortisol across the day compared to those who were unsure whether they would participate in a skydive or not, and those who knew for certain that they would not complete the skydive. The study assessing the psychobiological response to anticipation of a pleasant stimulus, however, revealed no significant effects. The exploration of a range of individual difference factors demonstrates the importance of appraisal of the event. That is, irrespective of the nature of the event, an individual’s perception of the event is an important determinant of psychological and biological responding. On the basis of the empirical findings of this thesis, it is concluded that both the laboratory and naturalistic stressors elicit some form of anticipatory response. This finding is in concordance with previous suggestions that the stress response can be observed prior to direct stressor exposure. Furthermore, exploration of the role of individual differences in the anticipation of novel events identified a number of characteristics which may serve to buffer or exacerbate the negative effects of prolonged stress on health outcomes. Finally, the findings from this thesis do not suggest that the anticipatory responses reported for stressors are extended to the anticipation of pleasant events, but that they may exclusively apply to stimuli perceived to be stressful and ultimately, a forthcoming demand. However, when individual differences are taken into account, it appears that the novelty of a forthcoming event in general may be more influential in appraisals of the event, rather than the nature of the task itself.
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