Research on the psychological and physiological stress-responses have been unable to fully clarify the underlying relationship. The unconscious stress hypothesis proposes that stress-related... Show moreResearch on the psychological and physiological stress-responses have been unable to fully clarify the underlying relationship. The unconscious stress hypothesis proposes that stress-related processes outside of awareness may negatively affect cardiovascular (CV) health by activating and even prolonging physiological stress-responses. This thesis provides a starting point in the exploration of the role of processes outside of awareness in cardiovascular stress research. The eight chapters discuss the findings of a systematic review and a series of experiments, using subliminal priming paradigms and fear conditioning, and address various theoretical and methodological issues to benefit future studies in this area. It seems evident that what is outside of awareness may influence the physiological state, but not necessarily all health-relevant parameters. The physiological changes related to unconscious stress appears to differ between the various stressful stimuli and stressors used. Show less
Ploeg, M.M. van der; Brosschot, J.F.; Versluis, A.; Verkuil, B. 2017
Negative affective information may be presented outside of awareness and change physiological activity. By increasing peripheral physiological activity, subliminally presented negative affective... Show moreNegative affective information may be presented outside of awareness and change physiological activity. By increasing peripheral physiological activity, subliminally presented negative affective information may contribute to the development of disease. The current systematic review evaluated 65 studies in which negative affective stimuli were presented subliminally to a healthy sample while cardiovascular, electrodermal, electromyographical, hormonal, or immunological activity was measured. Overall, 41% of the tested contrasts indicated significant increases due to negative affective stimuli compared to control stimuli. These effects were most pronounced in fear- conditioning studies measuring skin conductance response amplitude and priming studies measuring systolic blood pressure. However, across the included studies the methodology varied substantially and the number of contrasts per physiological parameter was limited. Thus, although some evidence exists that subliminally presented negative affective stimuli can induce adverse peripheral physiological changes, this has not yet been addressed sufficiently. Show less
Ploeg, M.M. van der; Brosschot, J.F.; Versluis, A.; Verkuil, B. 2017
Negative affective information may be presented outside of awareness and change physiological activity. By increasing peripheral physiological activity, subliminally presented negative affective... Show moreNegative affective information may be presented outside of awareness and change physiological activity. By increasing peripheral physiological activity, subliminally presented negative affective information may contribute to the development of disease. The current systematic review evaluated 65 studies in which negative affective stimuli were presented subliminally to a healthy sample while cardiovascular, electrodermal, electromyographical, hormonal, or immunological activity was measured. Overall, 41% of the tested contrasts indicated significant increases due to negative affective stimuli compared to control stimuli. These effects were most pronounced in fear-conditioning studies measuring skin conductance response amplitude and priming studies measuring systolic blood pressure. However, across the included studies the methodology varied substantially and the number of contrasts per physiological parameter was limited. Thus, although some evidence exists that subliminally presented negative affective stimuli can induce adverse peripheral physiological changes, this has not yet been addressed sufficiently. Show less
Self-report, i.e., explicit, measures of affect cannot fully explain the cardiovascular (CV) responses to stressors. Measuring affect beyond self-report, i.e., using implicit measures, could add... Show moreSelf-report, i.e., explicit, measures of affect cannot fully explain the cardiovascular (CV) responses to stressors. Measuring affect beyond self-report, i.e., using implicit measures, could add to our understanding of stress-related CV activity. The Implicit Positive and Negative Affect Test (IPANAT) was administered in two studies to test its ecological validity and relation with CV responses and self-report measures of affect. In Study 1 students (N = 34) viewed four film clips inducing anger, happiness, fear, or no emotion, and completed the IPANAT and the Positive And Negative Affect Scale at baseline and after each clip. Implicit negative affect (INA) was higher and implicit positive affect (IPA) was lower after the anger inducing clip and vice versa after the happiness inducing clip. In Study 2 students performed a stressful math task with (n = 14) or without anger harassment (n = 15) and completed the IPANAT and a Visual Analog Scale as an explicit measure afterwards. Systolic (SBP), diastolic (DBP) blood pressure, heart rate (HR), heart rate variability (HRV), and total peripheral resistance (TPR) were recorded throughout. SBP and DBP were higher and TPR was lower in the harassment condition during the task with a prolonged effect on SBP and DBP during recovery. As expected, explicit negative affect (ENA) was higher and explicit positive affect (EPA) lower after harassment, but ENA and EPA were not related to CV activity. Although neither INA nor IPA differed between the tasks, during both tasks higher INA was related to higher SBP, lower HRV and lower TPR and to slower recovery of DBP after both tasks. Low IPA was related to slower recovery of SBP and DBP after the tasks. Implicit affect was not related to recovery of HR, HRV, and TPR. In conclusion, the IPANAT seems to respond to film clip-induced negative and positive affect and was related to CV activity during and after stressful tasks. These findings support the theory that implicitly measured affect can add to the explanation of prolonged stress-related CV responses that influence CV health. Show less
