While most people are fairly familiar with the fight or flight response in animals, there exists a third response to stress: colloquially, the “freeze response” (also known as tonic immobility).
Humans are known to exhibit fight or flight responses on a daily basis. Explained broadly, the fight response is initiated when we instinctively feel we can battle our way out of a situation. The flight response, on the other hand, is initiated when we feel overwhelmed by a situation and spot an escape. Keep in mind: since it is a subconscious response to stimuli, our reaction might not make much logical sense. Maybe, when pressured by your boss and given a strict deadline with dire consequences, you amp up your workload and lose sleep for the next week trying to achieve the impossible. Another person, in the same situation, might become aggressive towards their boss and snippy to their loved ones until the deadline has passed. Both situations involve high levels of adrenaline and norepinephrine for extended periods of time, as well as elevated heart rate and blood pressure.
But what about the freeze response? In animals, it is triggered most commonly when trapped or captured. Tonic immobility (also known as thanatosis or “apparent death”) is displayed by animals under intense duress; think a possum playing dead or a deer in headlights. When placed in extreme situations–in particular, after being captured by a predator–many animals feign death. They appear paralyzed and are unresponsive to stimuli, yet are still fully conscious. Some animals, such as the hog nosed snake, even release a toxic-smelling odor. This fully cements the illusion that the snake is dead and rotting, and certainly not tasty. While references to tonic immobility in humans are splashed across our lexicon in the form of idioms and turns-of-phrases (see the aforementioned “deer in headlights”), there have been very few laboratory studies exploring its existence.
Biologically, animals exhibiting the freeze response display decreased heart rate, periods of eye closure, increases in body temperature and respiration, and frequently experience tremors (this was documented in a 1976 paper by G. G. Gallup and S. D. Suarez). It is commonly theorized that rape victims commonly experience this response during the assault, and in 2011 Eliane Volchan discovered that victims of traumatic stress in general–not just rape–also display these biological changes. Given that humans experience fight-or-flight responses on a daily basis, it can then plausibly be assumed that some humans also experience tonic immobility when feeling trapped or helpless (even if the stressor is not traumatic or life-threatening). If we do not believe in our own self-efficacy–or, in other words, our ability to escape or fight our way out of a stressful situation–we will “freeze.”
Oddly-enough, self-efficacy plays a major role in most theories of motivation (that is, what motivates humans to do things and why) in that, should we not believe we have the ability to accomplish a goal or goals, we won’t even make the attempt. In 1964, Victor H. Vroom developed the Expectancy Theory of Motivation that aimed to explain why individuals chose one behavioral path over others in the workplace. He wrote an equation designed to mathematically calculate the motivational force an individual would exert in order to accomplish a goal. When E = expectancy [or self-efficacy], I = instrumentality, and V = valance, the effort one is willing to put forth is equal to E (Σ I × V). Valence is defined as the value the employee places on accomplishing the goal, instrumentality as the belief that accomplishing the goal will result in some sort of benefit to the employee (even if it’s just pleasure at accomplishing a task), and expectancy as the belief that the goal itself can be accomplished. This means that, within Vroom’s equation, if we do not believe in our own self-efficacy we will not exert much–or any–effort.
Vroom’s Expectancy Theory deals with upper-level cognitive processes–but what about the subconscious? If you logically know yourself to be capable of accomplishing a task, you will eventually exert the necessary effort in order to complete it. But what about the rapidity with which those tasks are executed? Add in adrenaline (or trauma, or any number of other unpleasantries) and you’re dealing with stress responses on top of motivational effort. Looking back at the example given to illustrate possible fight-or-flight responses in humans–a strict deadline with dire consequences–a third possible story line emerges should you also consider the freeze response. Those who most commonly exhibit a fight-or-flight response will presumably appear as the typical overstressed worker: too little sleep, always buzzing, never sitting still, perpetually on-edge. But what if that same stressor coupled with a lack of intrinsic self-efficacy actually triggers a biological response–a freeze response? If you do not believe you can accomplish the project delegated to you (even if all logical markers suggest otherwise), you might sleep more every night. Even if you logically know the project can be completed, you might push it off until you are forced to confront it. You might, in other words, procrastinate. Procrastination could then be the freeze response rearing its head because of a subconscious but firmly-held belief that you are not capable.
Extrapolating on this idea, if chronic anxiety is technically a prolonged fight-or-flight arousal, perhaps depression (with its lack of motivation and increased sleep) is the prolongation of tonic immobility. It becomes plausible to imagine that the freeze response manifests itself as the physical symptoms of depression, and that depression itself is triggered by stressors coupled with the deeply-held belief that you are not capable of dealing with (or living) life for whatever reason. This could have far-reaching ramifications in the ways that PTSD and depression are treated pharmacologically and therapeutically.
Now, who wants to give me a lab so I can see if this idea has any bearing?