Traumatic events can trigger various physiological responses depending on the individual. When met with a potential threat and your brain has to act quickly and it is very common for individuals to go into a “fight” or “flight” mode. You either confront the perceived danger or run from it. Fight or flight reactions might be the better-known responses to danger, but research also identifies another potential response, the “freeze” effect. According to Dr. Rebecca Campbell the physiological reaction of freezing during trauma is termed Tonic Shock or Tonic Immobility, and can be very common in sexual assaults (Marx, Forsyth, Gallup, Fuse, & Lexington, 2008; Galliano, Noble, Travis, & Peuchl, 1993; Suarez & Gallup, 1979). 

        Advances in neurobiology and physiology help us better understand the connections between the brain and body when and individual experiences a traumatic event. According to Dr. Campbell, when the brain perceives a threat, real or not,  it activates a neurological chain reaction which leads to the release of several different hormones depending on what is needed. When various hormones are released into the body, they result in different reactions. For instance,  when an individual is exposed to physical or emotional trauma the adrenal system is activated in the body. Adrenaline helps facilitate a  fight or flight response, or a spike in natural painkillers such as Oxytocin and Cortisol that can help the body mitigate emotional and physical pain. Due to the physical and emotional trauma associated with sexual assault, it is common for the body to create an ample amount of these morphine-like chemicals to help protect a victim. One of the possible effects that can accompany this systematic reaction is a state in which the entire body shuts down. Dr. Campbell identified this processes when the body shuts down during and while recounting a sexual assault, as rape-induced paralysis. She notes that this state of “freezing” may actually be an evolutionary protective instinct. Similar to other animals such as possums that play dead or look dead, sometimes the act of not fighting back or fleeing (that would trigger a chase) is the safest thing for an organism to do when in danger. According to Dr. Campbell, in this physiological induced state an individual would not be able to move their body and access to certain parts of the brain that help make conscious decisions would be cut off; incapacitated by fear. It is predicted that between 12% and 50% of rape victims suffer from the tonic shock response which it critical to know if you are a first responder or reporting unit. 

    Reporting statistics are notoriously low  in regards to sexual assaults and rapes. According to Dr. Cambell, one explanation is that victims are met with apprehension or disbelief in regards to how they reacted to an attack. Furthermore, It can be hard to understand why someone enduring sexual trauma might not fight off their attacker or, at least, try to escape the situation. Learning more about the body’s chemical response to trauma and how it affects our physiological responses to trauma can help enlighten professionals to this phenomenon and potentially eliminate unsubstantiated judgments that negatively influence reporting outcomes. This information can be equally valuable to victims. It can help untangle and sort through misinformed feelings of self-blame, and redirect the blame and judgments to where it belongs, the perpetrators. Our bodies are designed to protect us from traumatic situations whether we are conscious of it or not, and this science heightens our abilities to understand why and how.        

References:

Marx, B. P., Forsyth, J. P., Gallup, G. G., & Fusé, T. (2008). Tonic immobility as an evolved predator defense: Implications for sexual assault survivors.Clinical Psychology: Science and Practice, 15(1), 74-90.       

Suarez, S. D., & Gallup, G. G. (1979). Tonic immobility as a response to rape in humans: A theoretical note. The Psychological Record, 29(3), 315.   
  
Galliano, G., Noble, L. M., Travis, L. A., & Puechl, C. (1993). Victim reactions during rape/sexual assault: A preliminary study of the immobility response and its correlates. Journal of Interpersonal Violence, 8(1), 109-114.