Tonic immobility as an evolved predator defense: Implications for sexual assault survivors.

Abstract

This article reviews research concerning the possible relationship between tonic immobility (TI) and human reactions to sexual assault. This review includes a description of the characteristic features of TI and a discussion of the most widely accepted theoretical explanation for TI. The possibility that humans may exhibit TI is explored and conditions that might elicit TI in humans are identified. In particular, we focus on TI in the context of sexual assault, because this form of trauma often involves elements that are necessary for the induction of TI in nonhuman animals, namely, fear and perceived physical restraint. The important similarities and differences in how TI manifests in humans and nonhuman animals are highlighted, future research directions are offered, and clinical implications are suggested.

Victims of rape show increased cortisol responses to trauma reminders: A study in individuals with war- and torture-related PTSD

“…The nearness of the perpetrator during the traumatic event might modulate peritraumatic physiologic responses, as well as later cortisol responses to trauma reminders. The direct physical contact with a perpetrator during sexual assault combined with extreme fear, could predispose sexual assault victims to display tonic (Suarez and Gallup, 1979;Marx et al, 2008) or flaccid (Schauer and Elbert, 2010) immobility, i.e. a shutdown response, when flight or fight has proven unsuccessful.…”

“…For example, Kaysen et al (2005) investigated women's peritraumatic responses to different forms of crimes and found that approximately one third of women reported active physical resistance (e.g., biting, cursing, kicking), whereas a large proportion of women, especially victims of rape, reported non-active behavioral responses, i.e., ''shut-down'' responses. In victims of sexual assault, the failure to escape or fight an assailant is typically followed by ''rape-induced paralysis'' (Burgess and Holmstrom, 1976), or tonic immobility (TI, Suarez and Gallup, 1979;Marx et al, 2008). During such an episode of rape-induced paralysis or TI, sexual assault victims find themselves unable to move, resist or incapable of calling out for help, while remaining conscious -eventually resulting in many cases in flaccid and unresponsive immobility or even fainting, mediated by vaso-vagal syncope (Schauer and Elbert, 2010).…”

Up speeds you down. Awe-evoking monumental buildings trigger behavioral and perceived freezing

“…Freezing is -besides fight and flight -one of the main stages of the defense cascade in both human and nonhuman animals (Marx et al, 2008;Hagenaars, Oitzl, & Roelofs, 2014), and specifically occurs when a threat has been first detected and/or encountered (Marx et al, 2008).…”

Predictores de la inmovilidad tónica ante eventos traumáticos

“…Tonic immobility (TI) is characterized by profound physical immobility, supressed vocal behaviour, trembling, muscular rigidity, a decrease in body temperature (cold sensations) and lack of sensitivity to intense or painful stimuli, although an awareness of surroundings remains. TI is triggered by situations of intense fear and physical restraint, although as it may occur without the latter it is likely that the perceived inability to escape is what matters (Heidt, Marx, & Forsyth, 2005;Marx, Forsyth, Gallup, Fusé, & Lexington, 2008;Moskowitz, 2004).…”

“…Various authors have described a sequence of four defensive responses linked to the proximity of danger: hypervigilance or freezing, escape, fighting and tonic immobility (Gray, 1987;Marx, Forsyth, Gallup, Fusé, & Lexington, 2008). Tonic immobility (TI) is characterized by profound physical immobility, supressed vocal behaviour, trembling, muscular rigidity, a decrease in body temperature (cold sensations) and lack of sensitivity to intense or painful stimuli, although an awareness of surroundings remains.…”