Diderot Effect is one new possession spirals into a cascade of complementary purchases. It sits in the Cognition dimension (COG) of the Human Behavior Taxonomy™ as element HBT-COG-0234, within the Decision family. The core principle: one new possession spirals into a cascade of complementary purchases. 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
One new possession spirals into a cascade of complementary purchases.
Plain-English Definition
One new possession spirals into a cascade of complementary purchases.
Feynman Explanation
You bought the robe. Now the chair has to go.
Core Principle
One new possession spirals into a cascade of complementary purchases.
Mechanisms
Pending editorial review.
One new possession spirals into a cascade of complementary purchases.
Pending editorial review.
Pending editorial review.
Pending editorial review.
Pending editorial review.
Product ecosystems engineer Diderot spirals on purpose.
Inputs (Triggers)
Pending editorial review.
Outputs (Behaviors)
Pending editorial review.
Behavioral Signature
You bought the robe. Now the chair has to go.
Examples
- Buying a new phone triggers cases, headphones, watches, a plan upgrade.
- Product ecosystems engineer Diderot spirals on purpose.
Pending editorial review.
Original analysis from The Incentives Lab — how this element behaves inside real payoff structures.
Why this element matters to incentive design
Executives usually notice this element only after it has cost something. By then it looks like a one-off. It is not. The mechanism underneath it is straightforward: one new possession spirals into a cascade of complementary purchases. You can recognize it in the field by its signature: you bought the robe. Now the chair has to go. 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, product ecosystems engineer Diderot spirals on purpose. It is amplified whenever product ecosystems engineer Diderot spirals on purpose. Inside organizations that shows up as product ecosystems engineer Diderot spirals on purpose. 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 name the cascade before the second purchase. The leverage is not in explaining the behavior to people. It is in changing what the behavior earns.
Famous Experiments
Pending editorial review.
Design Principles
- Name the cascade before the second purchase.
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.
- Name the cascade before the second purchase.
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.
A color appears different depending on adjacent colors.
The ability to focus on one voice in a noisy environment.
Evaluations are warped by what came immediately before.
We spend less when holding large bills than small ones — same money, different behavior.
Selling winners too early and holding losers too long.
We overweight one aspect of an event when predicting its impact.
One negative trait taints judgment of everything else about a person or company.
Evaluated separately, the smaller-but-complete option beats the larger-but-flawed one.
Goals become the focus, sometimes at the expense of the underlying purpose.
'Free' is a different psychological category — disproportionately attractive.
How will I feel about this in 10 minutes / 10 months / 10 years?
Inattention or forgetfulness caused by low attention, hyperfocus, or distraction.
Where Diderot Effect 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.
- ReferenceThe Periodic Table of Human Behavior
The full 1,267-element map this page belongs to.
Questions about Diderot Effect
- What is Diderot Effect?
- Diderot Effect is one new possession spirals into a cascade of complementary purchases. It sits in the Cognition dimension (COG) of the Human Behavior Taxonomy™ as element HBT-COG-0234, within the Decision family. The core principle: one new possession spirals into a cascade of complementary purchases. 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 Diderot Effect?
- Product ecosystems engineer Diderot spirals on purpose. The Incentives Lab catalogs everyday, organizational, and historical instances of this element on its Human Behavior Taxonomy™ page (HBT-COG-0234).
- How is Diderot Effect exploited?
- Product ecosystems engineer Diderot spirals on purpose.
- How do you design around Diderot Effect?
- Name the cascade before the second purchase.
- Which behavioral dimension does Diderot Effect belong to?
- Diderot Effect is classified in the Cognition dimension (COG) of the Human Behavior Taxonomy™, family "Decision", class "Mental Model". Its permanent identifier is HBT-COG-0234 and its evidence grade is B.