Fight-or-flight response

What is the fight-or-flight response?

The fight-or-flight response (Dutch: vecht-of-vluchtreactie) is the automatic alarm reaction with which the body responds to threat. The sympathetic nervous system switches on, the adrenal gland releases stress hormones and the body gets ready to fight or get away. There is a third outcome that happens more often than people think: freezing.

The responses the body picks from

Four, and you choose none of them consciously.

1. Fight. Pushing back, screaming, resistance.
2. Flight. Walking away, running off, leaving the room.
3. Freeze. No longer being able to move or speak. In the literature this is called tonic immobility.
4. Fawn. Going along with what the other person wants to make the threat stop. In English this is the fawn response.

The standard description notes that the broader set of responses, including freezing, fainting and startling, has led researchers to use more neutral terms than the original pair.

The word choice fits none of the four. These are reflexes that start before there is anything to weigh.

Where the term comes from

From a laboratory at Harvard, and the name is more than a hundred years old.

Walter Bradford Cannon described the phenomenon in 1914 and in 1915 coined the phrasing that stuck: the necessities of fighting or flight. It is in his book Bodily Changes in Pain, Hunger, Fear and Rage from that year. Cannon later, in 1929, also introduced the concept of homeostasis.

What he described was the physiology. The sympathetic nervous system sends signals from the hypothalamus that activate the heart and change the blood flow, and the adrenal medulla sets off a hormone cascade with mainly noradrenaline and adrenaline.

Freezing was not in the original pair. It was added later, and it is exactly the part that matters most for this site.

Why doing nothing is not consent

Because freezing during sexual violence is more the rule than the exception, and it happens involuntarily.

Anna Möller, Hans Peter Söndergaard and Lotti Helström studied this in 298 women who reported to the emergency department within a month of an assault or rape. In Acta Obstetricia et Gynecologica Scandinavica they reported that 70 percent experienced significant tonic immobility and 48 percent extreme tonic immobility during the event. At the six-month follow-up, that response turned out to be associated with developing post-traumatic stress disorder and severe depression.

The Centrum Seksueel Geweld (Centre for Sexual Violence) explains it plainly: “Tonic immobility is a natural and involuntary response of the body. You have no control over it.” The phenomena named are no longer being able to move, no longer being able to say anything, trembling, tense muscles, closed eyes, insensitivity to pain and a lower body temperature.

More than half of victims, according to that same factsheet, say they felt paralyzed during sexual violence. And the centre names what happens afterward: victims are often ashamed of their reaction and feel guilty because they “did nothing”. But they could not do anything.

From that follows the practical consequence that counts on this site. The absence of resistance says nothing about consent. Someone who stays still may be frozen.

What polyvagal theory says about this, and why it is contested

It is popular in trauma circles, and it is under heavy scientific pressure.

Stephen Porges’s polyvagal theory links two branches of the vagus nerve to different behavior patterns: one to defensive freezing, the other to social contact. It is the theory that concepts like neuroception and the window of tolerance come from, and it is widely used in trauma-informed work.

In Biological Psychology Paul Grossman laid out the five basic premises and concludes that each of them is “either untenable or highly implausible” on the basis of the available literature. His main objection: almost the whole theory hangs on one measurable phenomenon, respiratory sinus arrhythmia, and equating that with vagal tone he calls a category error.

That does not make the clinical work that grew out of it worthless. It does mean you should read the neurological explanation that comes with it with reserve. This page therefore names the theory, and does not present it as settled.

The words that come from trauma practice

A whole vocabulary surrounds this subject, and it pays to know where each word comes from.

Part comes from Porges’s polyvagal theory: neuroception, the unconscious scanning of whether a situation is safe, and co-regulation, the idea that two nervous systems calm each other. The window of tolerance, the zone where you can still think and feel at the same time, comes from psychiatrist Dan Siegel. These concepts are clinically useful; the neurological grounding underneath is the subject of the criticism above.

Another part comes from somatic experiencing, Peter Levine’s method. From it come titration, approaching what is too much in small doses, and pendulation, moving back and forth between tension and rest. In European Journal of Psychotraumatology Marie Kuhfuß and colleagues went through sixteen studies and conclude that the results are promising but “require more support from unbiased RCT-research”, with mixed study quality according to the Cochrane risk analysis.

Preliminary evidence, then, not settled. That is something other than no evidence, and something other than the certainty with which these words are sometimes used.

What this means for you: if someone hands you these terms, they are using a practice vocabulary and not physics. Feel free to ask what a claim rests on.

What can happen afterward

The reaction itself is short. What follows sometimes is not.

Two phenomena come up most often in this field. Dissociation is the feeling of not being fully present: as if you see yourself from a distance, or as if the body belongs to someone else. It is related to freezing and often occurs in the same situations. A flashback is reliving the event, unbidden and with the intensity of the moment itself.

Thuisarts.nl describes that last one as the hallmark of PTSD: “With PTSD you relive distressing events again and again in your thoughts or dreams.” The site names psychotherapy as a treatment that can help well, including going back to the events in your mind and eye-movement therapy, EMDR.

If the symptoms persist over time, the GP is the first step. They can refer you on.

What people get wrong about the fight-or-flight response

“There are two reactions: fight or flight.” That was Cannon’s division from 1915. Freezing was added later, and that reaction is exactly the one most reported in sexual violence.

“If you do nothing, you consent.” Wrong, and the research is firm about it. In 70 percent of the women studied, significant tonic immobility occurred, a reaction no one has control over.

“I could have done something.” The Centrum Seksueel Geweld names this as the core of the guilt afterward, and counters that there was nothing to be done. Remarks from those around you like “why didn’t you run” do not help the processing, according to them.

“Polyvagal theory explains this.” It offers an explanation, but that is under fire. Grossman argues that each of the five basic premises is untenable or highly implausible.

What you can do with this

• Do not blame yourself if you froze. It is an involuntary reflex, and according to the Centrum Seksueel Geweld a normal reaction to a very frightening event.
• Do not tell someone else what you would have done. Research shows that such remarks do not help the processing.
• Never treat silence as a yes. When in doubt you stop and ask. How that works is on consent.
• Seek help if the symptoms persist. Thuisarts.nl describes PTSD as reliving distressing events again and again in your thoughts or dreams, and names psychotherapy including EMDR as a treatment that can help well. For that, first go to your GP.
• Call the Centrum Seksueel Geweld if it concerns sexual violence. That is the right place, and this page is not.

Read more about the fight-or-flight response

Within this glossary, consent explains why consent has to be active and cannot be inferred from silence, and safeword describes the agreement that exists for the moment when talking becomes hard.

Beyond this site, the Centrum Seksueel Geweld factsheet is the best Dutch-language starting point, and Thuisarts.nl holds the information about PTSD that GPs use themselves.

Where this fits on this site

This page is here for one reason: a safeword only works if both people know that its absence proves nothing. Someone who freezes cannot say it. That is why I agree on a gesture beforehand alongside a word, and during a date I watch what a body does instead of what is not being said. More about those agreements is on consent.

Sources

• Tonic immobility during sexual assault - a common reaction predicting post-traumatic stress disorder and severe depression. Anna Möller, Hans Peter Söndergaard & Lotti Helström, Acta Obstetricia et Gynecologica Scandinavica 96(8), 932–938, 2017 (DOI 10.1111/aogs.13174). A study of 298 women who reported to the emergency department within a month of sexual violence, with a six-month follow-up of 189 of them. Supplies the finding that 70 percent reported significant tonic immobility and 48 percent extreme tonic immobility, and the link with developing post-traumatic stress disorder and severe depression.
• Factsheet Tonic Immobility. Centrum Seksueel Geweld, 2022. Supplies the description “Tonic immobility is a natural and involuntary response of the body. You have no control over it”, the symptom list of no longer being able to move, trembling, no longer being able to say anything, closed eyes, tense muscles, insensitivity to pain and a lower body temperature, the finding that more than half of victims felt paralyzed during sexual violence, and the passage about shame and guilt with the line “But they could not do anything”.
• Fundamental challenges and likely refutations of the five basic premises of the polyvagal theory. Paul Grossman, Biological Psychology 180, 108589, 2023 (DOI 10.1016/j.biopsycho.2023.108589). Supplies the finding that each of the five basic premises of polyvagal theory is “either untenable or highly implausible” on the basis of the available scientific literature, and the argument that equating respiratory sinus arrhythmia with general or cardiac vagal tone is a category error. The abstract was read via Europe PMC; the publisher’s site blocks automated access.
• Somatic experiencing, effectiveness and key factors of a body-oriented trauma therapy: a scoping literature review. Marie Kuhfuß, Tobias Maldei, Andreas Hetmanek & Nicola Baumann, European Journal of Psychotraumatology 12(1), 2021 (DOI 10.1080/20008198.2021.1929023). A review in which sixteen studies were systematically analyzed out of 83 articles found. Supplies the conclusion that there is preliminary evidence for positive effects on PTSD-related complaints, the finding that the results “require more support from unbiased RCT-research”, and the outcome of the Cochrane risk analysis that study quality is mixed.
• PTSS (post-traumatische stress-stoornis). Thuisarts.nl, Nederlands Huisartsen Genootschap. Supplies the description “With PTSD you relive distressing events again and again in your thoughts or dreams” and the treatment options, including going back to the events in your mind, calming your thoughts and eye-movement therapy (EMDR).
• Fight-or-flight response. English-language encyclopedia. Supplies the attribution to Walter Bradford Cannon, who described the phenomenon in 1914 and in 1915 spoke of “the necessities of fighting or flight” in his book Bodily Changes in Pain, Hunger, Fear and Rage, the physiology with the sympathetic nervous system and the release of catecholamines by the adrenal medulla, mainly noradrenaline and adrenaline, and the finding that the broader set of responses has led researchers to more neutral terminology than the original pair.

Related terms

The fight-or-flight response describes what a body does under threat; the terms below are about the agreements made around it.

• Consent. Why consent has to be active, and does not follow from silence.
• Safeword. The agreement for the moment when stop has to be said, and why a gesture belongs alongside it.
• Hard limit. What is ruled out beforehand, so there is less to decide during the date.
• Subspace. An altered state of awareness in which talking also becomes harder, with a very different cause.
• Aftercare. What is needed afterward when the nervous system is still switched on.
• Attachment style. The pattern with which someone organizes closeness, related to but not the same as the alarm reaction.
• Grounding. The technique that tries to break off this reaction, and what is known about the evidence.