Short Answer
Stress Shrinks Capacity and Hides the Damage
Under stress, most people:
Lose fine motor control.
Make riskier decisions.
Miss obvious errors.
Feel confident while performing worse.
The brain masks impairment — which is why overconfidence is so dangerous.
Physiology
What Stress Actually Does
Stress activates survival responses that trade precision for urgency.
Narrowed attention.
Reduced working memory.
Faster but sloppier decisions.
Higher energy cost per action.
Stress is optimized for escape, not problem-solving.
Illusion
Why Confidence Goes Up as Ability Goes Down
Stress chemicals blunt self-assessment.
Error detection weakens.
Feedback loops slow.
Certainty replaces accuracy.
Feeling “locked in” often means judgment is compromised.
Capacity Collapse
How Overestimation Breaks Plans
Overestimation creates fragile assumptions.
Distances planned at best-case pace.
Loads based on calm-day strength.
Timelines with no margin.
Decisions made too late.
Plans fail not because stress exists, but because it wasn’t accounted for.
Plan Design
Designing for Stress-Degraded Performance
Survivable plans assume reduced capacity.
Assume Slower and Weaker
Shorter distances
Lighter loads
More rest
Simplify Decisions
Fewer branches
Pre-made choices
Clear stop rules
Build Margin
Extra time
Extra energy buffer
Abort options
Bias Toward Stability
Shelter-in-place
Reduced movement
Lower exposure
FAQ
Does training prevent this?
Training helps, but stress still reduces performance — just less severely.
Is this fear-based?
No. It’s constraint-based. Ignoring limits is what creates danger.
What’s the biggest mistake?
Planning around how you perform on a calm, rested day.
Bottom line: Stress doesn’t reveal hidden strength.
It exposes the gap between plans and reality.
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