Sunk Cost (model form) is past investment is irrelevant to future decisions. It sits in the Cognition dimension (COG) of the Human Behavior Taxonomy™ as element HBT-COG-0648, within the Decision family. The core principle: past investment is irrelevant to future decisions. In incentive terms, it matters because it changes the payoff people perceive before they choose — which means it can be designed for, or exploited.
Scientific Definition
Past investment is irrelevant to future decisions.
Plain-English Definition
Past investment is irrelevant to future decisions.
Feynman Explanation
It's already gone. The only question is what's next.
Core Principle
Past investment is irrelevant to future decisions.
Mechanisms
Pending editorial review.
Past investment is irrelevant to future decisions.
Pending editorial review.
Pending editorial review.
Pending editorial review.
Pending editorial review.
Capital reallocation discipline.
Inputs (Triggers)
Pending editorial review.
Outputs (Behaviors)
Pending editorial review.
Behavioral Signature
It's already gone. The only question is what's next.
Examples
- Killing a project on its forward economics, not its history.
- Capital reallocation discipline.
Pending editorial review.
Original analysis from The Incentives Lab — how this element behaves inside real payoff structures.
Why this element matters to incentive design
Most organizations meet this element as a personnel problem. It is not one. The mechanism underneath it is straightforward: past investment is irrelevant to future decisions. You can recognize it in the field by its signature: it's already gone. The only question is what's next. Every element in the Cognition dimension changes the perceived payoff of an action before the action happens, which is exactly where incentive design has leverage.
How it gets exploited
Left undesigned, capital reallocation discipline. It is amplified whenever capital reallocation discipline. Inside organizations that shows up as capital reallocation discipline. The pattern is the same one Goodhart's Law describes: the measurable proxy attracts the effort, and the purpose behind it quietly loses funding.
How the Lab designs around it
The redesign move is to decision template that asks: 'If we were starting fresh today, would we fund this?'. Measure the behavior, not the sentiment. A survey will tell you how people feel about this; only observed action tells you whether it changed.
Famous Experiments
Pending editorial review.
Design Principles
- Decision template that asks: 'If we were starting fresh today, would we fund this?'
Measurement Approaches
Pending editorial review.
Evidence
Pending editorial review.
Pending editorial review.
The Perverse Incentive Lens™
How this behavior is exploited — and how to redesign around it.
- Decision template that asks: 'If we were starting fresh today, would we fund this?'
Pending editorial review.
Pending editorial review.
Interactive Mini Network
Click any neighbor to re-center the graph and follow the threads of connection.
Knowledge Graph Neighbors
Auto-linked to the rest of the Human Behavior Taxonomy by family, domain, dimension, and shared keywords.
Past investment should not influence future decisions.
Every yes is a no to everything else competing for that hour, dollar, or slot.
How will I feel about this in 10 minutes / 10 months / 10 years?
Inattention or forgetfulness caused by low attention, hyperfocus, or distraction.
Forgetting to compare an offer with the next-best alternative.
Outcomes that could have happened but did not.
Overthinking a situation so that decision-making stalls.
The first number on the table silently sets the range for every number after it.
Tversky & Kahneman's classic: identical outcomes flip from 'risk averse' to 'risk seeking' when framed as lives saved vs. lives lost.
Our perception is shaped by what we selectively pay attention to.
Favoring suggestions from automated systems over conflicting human judgment.
A color appears different depending on adjacent colors.
Where Sunk Cost (model form) is cited in the corpus
Essays, field guides, and diagnostics from The Incentives Lab that apply this element.
- EssayGoodhart's Law in the Real World
How measurable proxies capture judgment.
- EssayThe Perverse Incentives Hiding in Your KPIs
Cognitive shortcuts turned into scorecards.
- EssayAI Agents Inherit Your Incentives
How this element propagates into automated systems.
- ReferenceThe incentive glossary
Definitions for every mental model, bias, and fallacy in the corpus.
- CourseIncentives 101
The free ten-part primer on reading a payoff structure.
- ReferenceThe Periodic Table of Human Behavior
The full 1,267-element map this page belongs to.
Questions about Sunk Cost (model form)
- What is Sunk Cost (model form)?
- Sunk Cost (model form) is past investment is irrelevant to future decisions. It sits in the Cognition dimension (COG) of the Human Behavior Taxonomy™ as element HBT-COG-0648, within the Decision family. The core principle: past investment is irrelevant to future decisions. In incentive terms, it matters because it changes the payoff people perceive before they choose — which means it can be designed for, or exploited.
- What is an example of Sunk Cost (model form)?
- Capital reallocation discipline. The Incentives Lab catalogs everyday, organizational, and historical instances of this element on its Human Behavior Taxonomy™ page (HBT-COG-0648).
- How is Sunk Cost (model form) exploited?
- Capital reallocation discipline.
- How do you design around Sunk Cost (model form)?
- Decision template that asks: 'If we were starting fresh today, would we fund this?'
- Which behavioral dimension does Sunk Cost (model form) belong to?
- Sunk Cost (model form) is classified in the Cognition dimension (COG) of the Human Behavior Taxonomy™, family "Decision", class "Mental Model". Its permanent identifier is HBT-COG-0648 and its evidence grade is B.