under threat (what changes, and why)
by CEJames (arthor) & Akira Ichinose (editor/researcher)
When a situation is perceived as dangerous, two tightly-coupled stress systems ramp up:
• SAM / sympathetic-adrenomedullary system → fast surge of epinephrine (adrenaline) and norepinephrine, raising heart rate, blood pressure, breathing, glucose availability, and alertness.
• HPA axis → slightly slower hormonal cascade (CRH → ACTH → cortisol) that reallocates energy and modulates brain systems involved in memory and decision-making.
Those changes can be performance-helpful for simple, well-grooved actions, but they often degrade complex cognition and fine control under high threat.
Note: a solid discussion for the KISS principle in physical self-defense training, practice and especially application ergo defend through avoidance, etc.!
1) Perception limits under threat
Attentional narrowing (“tunnel vision” as attention, not eyeballs)
A classic finding is that high emotion/arousal tends to reduce the range of cues you use, prioritizing what seems most relevant. This is often framed as cue utilization narrowing. Modern work suggests the story is nuanced: “narrowing” can reflect prioritization of high-value cues rather than a uniform collapse of perception.
Practical meaning:
you may look at or notice the most threatening element (hands, weapon, sudden movement) while missing peripheral details (routes, bystanders, accomplices).
Weapon focus (attention hijack + memory tradeoff)
In eyewitness research, the presence of a weapon often draws gaze and attention toward it and reduces memory for other details(e.g., face/clothing). This effect is well-supported, with a large body of follow-up work.
Auditory exclusion and time distortion (reported in real incidents)
In lethal-force incidents, officers (LEO) frequently report sensory distortions such as:
• time slowing or speeding
• altered sound (including “auditory exclusion”)
• visual distortions/tunnel attention
A well-cited dataset reports slow-motion experiences in a majority of shootings in their sample.
Important caveat: these are self-reports (real and common, but not perfect measures of sensory physiology).
2) Reaction time under threat (and why it’s slower than people think)
Simple reaction time vs. real-world reaction time
• In lab settings, simple reaction time is often on the order of ~140–200 ms depending on modality (auditory typically faster than visual).
• But real self-defense decisions aren’t “press a button when light appears.” They include:
1. detect the cue
2. interpret it (friend/foe? weapon? intent?)
3. choose a response
4. initiate and control movement
Each layer adds time and error risk—especially under ambiguity and stress.
Choice + decision complexity: Hick–Hyman law
As the number of plausible responses increases, decision time tends to rise (roughly logarithmically)—a robust finding in choice reaction research.
Implication: under threat, simplifying “if/then” options (trained defaults) can be faster than “inventing” a response.
Stress and the prefrontal cortex (PFC): worse top-down control
High stress releases catecholamines that rapidly impair prefrontal networks responsible for working memory, inhibition, flexible reasoning, and “staying wise.”
Implication: you may revert to habit, freeze, perseverate, or overcommit to a first interpretation.
3) Adrenaline/cortisol effects on performance
Motor control: gross actions survive; precision often suffers
Under high stress, many people show:
• shakier precision
• degraded sequencing
• poorer inhibition (trigger-happy / premature action)
This lines up with the idea that stress biases toward habitual and emotional systems rather than deliberative control.
In police research under realistic threat (e.g., “shootback” scenarios), stress/anxiety is associated with reduced shooting accuracyand other performance impairments.
Memory: strong for “central threat,” worse for details
Acute stress can enhance memory for emotional/central elements yet impair recall of peripheral/unrelated details, and stress timing matters (encoding vs. retrieval).
4) What improves performance under threat (evidence-based levers)
Stress exposure training (inoculation) can help
In controlled police studies, training that includes anxiety/threat (vs. calm repetition) can reduce later performance drop under pressure—effects lasting months in at least one design.
Train the “defaults” you want to occur
Because stress can reduce flexible cognition and push you toward habit, you generally want:
• fewer choices (clear rules)
• simpler motor programs
• more repetition under realistic arousal
This is consistent with Hick–Hyman decision effects and stress/PFC findings.
Fact check of the key claims (what’s solid vs. shaky)
Very well-supported (strong evidence / broad consensus)
• Stress activates SAM (catecholamines) and HPA (cortisol) with widespread physiological effects.
• High stress can impair prefrontal executive functions (working memory, inhibition, flexibility).
• Weapon focus: attention drawn to weapon; memory for other details often reduced.
• Decision complexity increases response time (Hick–Hyman law).
• Stress effects on memory are timing- and content-dependent (can help emotional central elements, harm peripheral or retrieval).
Supported but with important caveats
• “Tunnel vision” / attentional narrowing: supported as reduced cue utilization under emotion/arousal, but mechanisms and generality vary; it’s not always a literal visual field failure.
• Auditory exclusion and time distortion: commonly reported in real lethal-force incidents; self-report evidence is strong for prevalence, but it’s not a precise physiological measurement.
• Threat degrades complex performance (e.g., shooting accuracy): supported in realistic simulation research; how much it degrades depends on training, task, and scenario.
Shaky / often overstated (use caution)
• Hard “heart-rate performance zones” (e.g., exact BPM cutoffs where skills shut down): widely circulated in tactical folklore and some training literature, but the precise thresholdsare not established as universal biological laws. If you use them, treat as rough coaching heuristics, not guaranteed physiology.
Bibliography (starter pack, strong sources first)
Stress physiology & brain
• Arnsten, A. F. T. (2009). Stress signalling pathways that impair prefrontal cortex structure and function. Nature Reviews Neuroscience.
• Arnsten, A. F. T. (2015). The effects of stress exposure on prefrontal cortex. Current Opinion in Behavioral Sciences.
• Herman, J. P., et al. (2016). Regulation of the hypothalamic-pituitary-adrenocortical stress response. Comprehensive Physiology.
• Godoy, L. D., et al. (2018). A comprehensive overview on stress neurobiology. Frontiers in Behavioral Neuroscience.
Memory under stress
• Klier, C., et al. (2020). Stress and long-term memory retrieval: A systematic review.
• Shields, G. S., et al. (2022). Stress and memory encoding: roles of stressor-relatedness and timing.
• Gagnon, S. A., & Wagner, A. D. (2016). Acute stress and episodic memory retrieval (review).
Attention and narrowing
• Easterbrook, J. A. (1959). The effect of emotion on cue utilization and the organization of behavior. Psychological Review.
• van Steenbergen, H., et al. (2011). Threat (more than arousal) narrows attention.
Reaction time / decision complexity
• Hick, W. E. (1952). On the rate of gain of information. Quarterly Journal of Experimental Psychology.
• Proctor, R. W., & Schneider, D. W. (2018). Hick’s law for choice reaction time: A review. Quarterly Journal of Experimental Psychology.
• BioNumbers entry on reaction times (auditory/visual/tactile) (compiled from classic RT literature).
Real-world / applied threat performance
• Nieuwenhuys, A., & Oudejans, R. R. D. (2011). Training with anxiety: effects on police shooting under pressure. Cognitive Processing.
• Klinger, D. A., & Brunson, R. K. (summary at OJP/NIJ): Perceptual distortions during lethal force incidents.
• Loftus, E. F., Loftus, G. R., & Messo, J. (1987). Some facts about “weapon focus”. Law and Human Behavior.
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