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Psychology & Behavior

Momentum Bias

Model #0948Category: Psychology & BehaviorDepth to apply:

By Updated

4 min read

Contents

  1. 1. Core Idea
  2. 2. How to See It
  3. 3. How to Use It
  4. 4. Founders & Leaders
  5. 5. Connected Models
  6. 6. One Key Quote
  7. 7. Summary & Further Reading
Psychology & Behavior
Section 1

Core Idea

Momentum Bias is the tendency to continue a course of action primarily because it's already in motion — not because ongoing evidence supports it. Once energy, resources, and identity have been invested in a direction, the psychological cost of stopping exceeds the logical cost of continuing, even when the original rationale has evaporated. In physics, momentum is neutral; in psychology, it's a trap. Founders keep scaling a failing product because the team is already built. Investors keep doubling down because they've already committed capital. Executives keep pursuing an acquisition because the process has gone too far to stop. Momentum Bias is distinct from Sunk Cost Fallacy in emphasis: sunk cost focuses on past investment; momentum bias focuses on the feeling that motion equals progress. The most dangerous form is when momentum is mistaken for validation.

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Section 2

How to See It

Product
You're seeing it when a company keeps investing in a product line that hasn't met any of its original milestones, but the team says they're "too far along to stop now." The justification isn't evidence of future success — it's the discomfort of halting something in motion.
Strategy
You're seeing it when a strategic initiative continues to absorb resources quarter after quarter, not because it's delivering results but because pausing would require admitting the original decision was wrong — and nobody wants to be the one who stops the train.
Section 3

How to Use It

Institute regular "zero-based" reviews where every continuing initiative must re-justify itself as if it were being proposed fresh. Remove the implicit advantage that existing projects have over new proposals. Ask: if we weren't already doing this, would we start it today given what we now know? If the answer is no, momentum — not merit — is keeping it alive.
Decision filter
"If this initiative came to me today as a new proposal with no prior investment, would I approve it based on current evidence?"
As a founder
Schedule quarterly "kill reviews" where you evaluate every active project as if it were a new proposal. Strip away the history, the team's emotional investment, and the narrative of progress. Evaluate only on current evidence and future expected value. The projects that survive this filter are genuine; the ones that can't are running on momentum.
Section 5

Founders & Leaders

Andy GroveCo-founder and CEO of Intel
Grove's pivot from memory chips to microprocessors is the canonical example of overcoming momentum bias. Intel had massive momentum in memory — an entire organisation, identity, and revenue stream built around it. The rational case for microprocessors existed, but the momentum of the memory business made it psychologically impossible for most leaders to stop. Grove's breakthrough was recognising that momentum was the obstacle, not logic. His "revolving door" thought experiment — imagining a new CEO walking in and making the obvious call — was a tool for neutralising momentum bias by removing the emotional weight of having been in motion. For founders, Grove proves that the hardest decisions aren't about finding the right answer but about stopping the wrong momentum.
Section 7

Connected Models

Reinforces
[Status Quo Bias](/mental-models/status-quo-bias)
Status Quo Bias favours the current state. Momentum Bias is its dynamic cousin — rather than preferring stillness, it prefers continuing in the current direction. Both resist change, but momentum bias disguises resistance as progress.
Pairs-with
Sunk [Cost](/mental-models/cost) Fallacy
Sunk Cost Fallacy justifies continuing because of past investment. Momentum Bias justifies continuing because of current motion. Together they create a powerful one-two punch — past costs make stopping painful, and current motion makes stopping feel wasteful.
Tension
[Inertia](/mental-models/inertia)
Inertia resists change in either direction — starting or stopping. Momentum Bias specifically resists stopping once motion has begun. The tension is that inertia can actually be useful (preventing rash starts), while momentum bias is almost always harmful (preventing necessary stops).
Section 8

One Key Quote

"There is at least one point in the history of any company when you have to change dramatically to rise to the next level of performance. Miss that moment and you start to decline."
— [Andy Grove](/people/andy-grove)
Section 11

Summary & Further Reading

Momentum Bias is the tendency to continue a course of action because it's already in motion, mistaking movement for progress. In business, it keeps failing products alive, sustains bad strategies, and prevents necessary pivots. Counter it with zero-based reviews that force every initiative to re-justify itself as if it were being proposed for the first time.

Why this matters next

mental modelsMomentum

Momentum Bias applied the Momentum mental model

mental modelsInertia

Momentum Bias applied the Inertia mental model

mental modelsNarrative

Momentum Bias applied the Narrative mental model

mental modelsCost

Momentum Bias applied the Cost mental model

mental modelsThought Experiment

Momentum Bias applied the Thought Experiment mental model

mental modelsStatus Quo Bias

Momentum Bias applied the Status Quo Bias mental model

Frequently asked questions

What is Momentum Bias?

Momentum Bias is a mental model used for better thinking and decision-making.

How do you apply Momentum Bias?

To apply Momentum Bias, identify situations where this framework is relevant, then use it as a lens to evaluate your options and decisions. The model is most useful when combined with other complementary mental models.

What category does Momentum Bias fall under?

Momentum Bias falls under the Psychology & Behavior category of mental models. Other models in this category can be found on the Psychology & Behavior hub page.

Why is Momentum Bias important?

Momentum Bias is important because it provides a structured way to think about problems that would otherwise be approached with intuition alone. Understanding this model helps you avoid common reasoning errors and make better decisions.

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