Dragt, Karlijn (2024) Physiological Mechanisms Underlying the Passive Defence Response in Human Individuals: A Systematic Review. Master thesis, Psychology.
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Abstract
Background: Exposure to a traumatic event is a common human experience, with approximately 65% of the individuals in the Netherlands having undergone such an event. Traumatic events can elicit a range of responses, including what is commonly referred to as the ‘freeze response’. The freeze response is a natural survival mechanism observed in individuals facing threats, yet the physiological mechanisms underlying this response remain poorly investigated among human individuals. Objective: Within this systematic review, we synthesize research which investigate the physiological mechanism that underlie the human passive defence response (i.e., initial freeze response, tonic- and collapsed immobility). Method: A systematic search for matching publications was performed using PubMed and Medline. From 971 initially identified studies investigating the physiological mechanisms that underlie the human passive defence response, 10 studies (n = 324) were included in the final analysis. Results: Among the ten selected studies, heterogeneity was observed in several study characteristics, including participants characteristics and methodological measurements. In examining heart rate responses, a consistent trend was identified among individuals without trauma exposure, where all studies reported a decrease in heart rate responses. In contrast, the individuals with trauma exposure, including those with PTSD, exhibited variability in heart rate responses, with some studies indicating an increase and others a decrease. Similar results were observable for body sway responses. Trends in body sway were apparent among individuals without trauma exposure, exhibiting reduced body sway responses. However, such a trend was not evident among those with trauma exposure, as one study revealed no significant difference, another indicated an increase, and a third reported a decrease. Although 4 skin conductance was evaluated in only one study, the expected outcome of an increase in skin conductance was observed. Conclusion: The results suggest different patterns in physiological responses between individuals with and without trauma exposure. Specifically, individuals without trauma exposure typically exhibit an expected reduction in heart rate and body sway. On the contrary, these patterns are not consistently observed in individuals who have been exposed to trauma.
| Item Type: | Thesis (Master) |
|---|---|
| Supervisor name: | Cuijpers, L.S. |
| Degree programme: | Psychology |
| Differentiation route: | Ontwikkelingspsychologie (O) [Master Psychology] |
| Date Deposited: | 03 Jul 2024 14:40 |
| Last Modified: | 03 Jul 2024 14:40 |
| URI: | http://gmwpublic.studenttheses.ub.rug.nl/id/eprint/3642 |
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