Fight, Flight, Freeze & Fiddle: Inside Your Dog’s Survival Brain

Animals, including our companion dogs, have evolved a handful of powerful survival strategies. When faced with threat, uncertainty, or internal conflict, they often shift into a “4-F” mode: Fight, Flight, Freeze, or Fiddle (also known as displacement behaviour). These responses aren’t just random quirks: they are deeply rooted in neurobiology.

These states are deeply rooted in evolution and governed by fast, powerful neurobiological circuits designed to keep an organism alive, not cooperative.

Understanding them helps explain why a dog in distress often cannot think, learn, or respond rationally and why displacement behaviour is more than a cute or annoying habit. When survival circuits activate, the thinking parts of the brain are essentially sidelined.

The Neurobiology of Survival Mode

When an animal perceives danger, real or perceived, its amygdala, a deep brain structure tied to emotion and threat detection, springs into action. This triggers a cascade via the hypothalamic–pituitary–adrenal (HPA) axis and the sympathetic nervous system. As a result, chemicals like adrenaline (epinephrine) and noradrenaline (norepinephrine) surge, priming the body for rapid, physical action. Simultaneously, cortisol is released, mobilising energy by increasing blood sugar and suppressing non-essential systems like digestion or long-term growth.

At the same time, the prefrontal cortex (PFC), the part of the brain responsible for decision-making, impulse control, and learning, becomes suppressed under heavy stress. According to Arnsten (2009), when stress signalling is very strong, PFC function degrades, meaning the animal can no longer engage in higher-order thinking or reflective behaviour. In survival mode, the brain prioritises reflex and instinct over rationality.

The Four Fs in Behaviour

1. Fight

In a fight response, the animal is preparing to confront a threat head-on. Behaviourally, this may look like growling, snarling, lunging, stiff-posturing, or snapping. These are not necessarily “dominance” behaviours more often, they are defensive, survival-driven reactions.

Neurochemically, this involves a strong sympathetic drive: adrenaline and noradrenaline flood the system, increasing heart rate, blood pressure, and muscle readiness. Cortisol further supports the metabolic demands of this response by ensuring there's enough glucose in the bloodstream. With the prefrontal cortex offline, inhibition is reduced, and defensive aggression can take over in a nearly automatic way.

The animal is not choosing to be “reactive”, its brain is prioritising survival, not social behaviour.

2. Flight

Flight is the urge to run away or distance oneself from perceived danger. You might see a dog that tries to retreat, hides, shakes, or veers away, possibly trembling or backing off from whatever is threatening.

From a biochemical standpoint, flight also involves the sympathetic nervous system, with adrenaline and noradrenaline driving rapid movement and scanning for escape paths. The same HPA axis activation ensures sustained arousal, and the locus coeruleus (a brainstem structure) (Rajkowski et al., 1994) may contribute to heightened vigilance, making the animal intensely aware of its environment and possible exits.

3. Freeze

Freeze is a state of immobility, sometimes described as “playing dead” or “shutting down.” The animal might go very still, hold its breath or breathe shallowly, and appear statue-like. Eyes may widen, ears flatten, body tense, but no overt action follows.

Unlike fight or flight, freeze often involves activation of the parasympathetic nervous system, particularly the dorsal branch of the vagus nerve (Porges, 2007). This can lead to bradycardia (slowed heart rate), muscle tension without movement, and sometimes a release of endogenous opioids, which dampen pain or fear. In effect, the body is braced and ready, but movement is inhibited. Despite seeming calm, the neurochemical stress response (e.g., cortisol) is still very active.

A classic example is an animal behaving ‘better’ when placed on the veterinary table for examination.

4. Fiddle / Displacement Behaviour

Here’s where nuance matters: displacement behaviour (the “fiddle” or “fidget”) isn’t just about little stress “tics”; it often reflects motivational conflict or frustration, and when excessive, it can interfere with normal functioning.

What Displacement Behaviours Look Like

In dogs, displacement behaviours can include yawning, lip licking, scratching, excessive self-grooming, sniffing the ground when there’s no scent to follow, shaking, or even manipulating objects in their environment (plus more). These actions often appear when the dog is conflicted, perhaps wanting to approach but also wanting to retreat, or wanting a reward but unable to obtain it.

Importantly, displacement behaviour has been defined in two overlapping ways:

1. As a behaviour performed in an “inappropriate” context relative to the immediate motivation (e.g., scratching when there’s no itch) (Hecht and Horowitz., 2015)
2. As any behaviour performed to excess that interferes with normal function, which often reflects frustration or chronic motivational conflict (Pedretti et al., 2022)

Frustration arises when an expected outcome is blocked. In dogs, this might be when a previously rewarded action is no longer reinforced (an extinction scenario), or when a desired resource is delayed, reduced in value, or physically inaccessible (Vekony et al., 2024).

Behaviourally, this frustration can show up as increased withdrawal, vocalisation, pacing, side-orientation (turning away), or other displacement acts like sniffing, yawning, and lip licking.

Why Displacement Happens: Neurochemical Underpinnings

From a neurochemical perspective, the frustration system is complex. According to research on canine emotion, key modulators include dopamine, glutamate, substance P, and acetylcholine (Heath, 2017).

• Dopamine is deeply tied to motivation and reward. When an expected reward is blocked, dopamine signalling can become disordered, contributing to frustration.
• Substance P is involved in pain and stress processing, possibly linking the emotional “sting” of frustration to behavioural expression.
• Glutamate and acetylcholine participate in neural circuits of conflict and arousal helping drive the tension that fuels displacement behaviours.

Behaviourally, displacement acts may also serve as coping strategies. In some species, they help redirect conflicting motivational energy into a “safer” behaviour, potentially reducing stress (Pedretti et al., 2022).

However, when these behaviours become excessive, scratching so much they injure themselves, constant pacing, obsessive licking, excessive grass eating, they cross into pathology. In dogs, studies have correlated higher frustration questionnaire scores with increased cortisol in saliva, indicating a physiological stress burden (McPeake et al., 2021).

Frustration, Conflict & Problem Behaviour

Frustration is not just a fleeting annoyance, it can become a significant emotional state that contributes to problematic behaviours. Frustration has been identified (alongside fear) as a frequent driver of behavioural issues in dogs (Wilson et al., 2024).

For example, when a dog’s expected reward is delayed, cancelled, or blocked, the dog may initially try to perform the behaviour (seeking), but when it fails, frustration sets in. Over time, repeated frustration without resolution can escalate: displacement behaviours intensify, vocalisations increase, and the animal may even develop redirected aggression (biting objects or people) as a way to discharge that internal tension (Dickinson and Feurbacher., 2025).

Moreover, in kennel or shelter settings, dogs showing displacement and frustration behaviours are often cycling through an “escalation loop,” where thwarted motivation (e.g., to play or eat) causes rising arousal, stress, and further displaced behaviour which in turn prevents relaxation and normal functioning (McBride and Hinde-Megarity, 2022).

The displacement behaviours an animal exhibits are a way for them to release tension and help the animal managed emotional overload.

Why a Dog Can’t “Just Obey” When in One of the Fs

When a dog is experiencing Fight, Flight, Freeze, or Fiddle, its brain is not in a state to process cues, learn new cues, or regulate impulses. The prefrontal cortex, which is essential for self-control, attention, and rational response, is suppressed under intense stress (Arnsten, 2009).

In displacement/frustration states especially, the dog’s neurochemical systems dopamine, substance P, glutamate, acetylcholine are all signalling conflict, unmet goals, and emotional tension. Rather than being “distracted,” the dog is overwhelmed by internal motivational conflict that hijacks its ability to focus on a cue or follow an instruction.

Put simply: when your dog yawns, licks its lips, scratches obsessively, or paces in a tense moment, it’s not being stubborn. Its brain is caught in a stress-regulation loop, not a training loop.

This means your dog isn’t being stubborn, disobedient, or dramatic. Their brain is literally unable to process training cues during stress. This is why effective training must prioritise emotional safety, predictable environments, and gradual exposure not forcing compliance during distress.

Implications for Training, Welfare, and Communication

Understanding the 4 F’s, especially displacement, has practical ramifications for anyone working with animals: trainers, behavioural therapists, and pet owners alike.

1. Training during calm states: Trying to teach or enforce cues while a dog is in a high-stress F-state is unlikely to be effective. Behaviour change is best introduced when the dog’s physiological arousal is low, and its prefrontal cortex can engage.
2. Recognising displacement as communication: Displacement behaviours are not meaningless. They often indicate internal conflict, frustration, or stress. Being able to read and respond to them is a valuable tool in building trust and managing welfare.
3. Addressing the root cause, not just the behaviour: If a dog consistently shows displacement behaviours (especially excessive ones), it may be a red flag for chronic frustration, lack of control, or unmet needs. Behavioural interventions should focus on environmental management, providing predictable routines, ensuring reward access, and reducing conflict or uncertainty.
4. Welfare assessment: In shelters, kennels, or veterinary contexts, observing displacement behaviours gives insight into an animal’s emotional state. Excessive fiddle behaviour may suggest poor welfare, chronic stress, or frustration all of which need addressing.

The “4 F’s”. Fight, Flight, Freeze, and Fiddle are not just behavioural cliches. They are deeply embedded survival strategies governed by powerful neurochemical systems. While fight, flight, and freeze are about direct response to threat, displacement (fiddle) behaviour reflects internal conflict and frustration, especially when the animal’s goals are blocked or its motivation is thwarted.

Because these systems suppress higher-order brain functions, a dog in any of these states simply can’t “listen” in the way it would when calm. For behaviour change to stick, the focus must be on reducing triggers, supporting emotional regulation, and building trust not just drilling obedience.