‘Playing dead’ – Modelling consequences of tonic immobility

Project in LISS Call 2018
Researchers: Muriel Hagenaars (UU), Jacques Hagenaars (TiU)

In extreme danger, the best-known automatic reactions are probably to fight or to flight. But a third, relatively unknown response is tonic immobility (‘playing dead’), which occurs especially in (perceived) unescapable threatening situations. Tonic immobility increases survival chances in animals hunted by predators. It is potentially beneficial in the short term in humans too, as it is associated with decreased physiological damage. However, in the long term human tonic immobility is associated with a higher risk of psychiatric symptoms, like posttraumatic stress disorder (PTSD), depression and dissociative symptoms. These findings were confirmed in earlier studies in the LISS panel in 2011 and 2012.

In this new study, the researchers aim to investigate when and how tonic immobility promotes PTSD development. Estimates of trauma prevalence in the general populations show that about 4830 to 6279 of the 7000 LISS respondents will have experienced trauma. Of those, 821 to 1067 will have PTSD, which will give the experiment sufficient power. The questionnaire will contain 30 items about tonic immobility, trauma and PTSD symptoms, as well as mediating and moderating factors.

Image: ErikaWittlieb voor Pixabay

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