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The Incentives Lab
Mental Models · Economics

Complements & Substitutes

Complements raise each other's value; substitutes lower it.

"Find your complement. Avoid being someone's substitute."

Quick answer

What is Complements & Substitutes? Complements raise each other's value; substitutes lower it. Strategic positioning is largely about which side of this you're on.

In the wild

Cloud + AI are complements; horse + car were substitutes.

Why it matters in the room

Strategic positioning is largely about which side of this you're on.

Counter-move

Map every key partner and competitor as complement or substitute.

Visual · Pattern
Complements & Substitutes — a recurring shape in how people decide.
Live example · Apply Complements & Substitutes

Use the model. Pick the move.

Complements raise each other's value; substitutes lower it. You've just seen this: Cloud + AI are complements; horse + car were substitutes. Which lever does the model recommend?

● Live

Pick a lever. There are no neutral ones — every incentive funds a behavior somewhere.

How does this land?

Pick a reaction to Complements & Substitutes

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Human Behavior Element™ · HBE Spec

The full taxonomy entry

Every concept in the Atlas uses the same structure — so Complements & Substitutes can be compared, recombined, and cited like an element on a periodic table.

About the standard →
M
CS
HBT-M7323
Official name
Complements & Substitutes
Mental Models · Economics
Identity
HBT ID
HBT-M7323
Symbol
CS
Official name
Complements & Substitutes
Synonyms
Economics
Keywords
Mental Models, Economics, human behavior, incentive design
Version
v1.0
Last updated
Maintained by The Incentives Lab
Classification
Kingdom
Cognition
Domain
Frameworks
Family
Mental Model
Class
Economics
Element
Complements & Substitutes
Definition
Scientific
Complements raise each other's value; substitutes lower it.
Plain-English
Complements raise each other's value; substitutes lower it.
Feynman
Find your complement. Avoid being someone's substitute.
Core principle
Complements raise each other's value; substitutes lower it.
One-sentence summary
Strategic positioning is largely about which side of this you're on.
Mechanisms
Psychological
Complements raise each other's value; substitutes lower it.
Behavioral econ.
Strategic positioning is largely about which side of this you're on.
Neurological
Reward, threat, and salience circuits bias attention toward the cue.
Evolutionary
Heuristics that paid off in ancestral environments now misfire in modern systems.
Sociological
Group norms and status incentives reinforce the pattern across a team.
Computational
Models trained on biased human signals will replicate and amplify the pattern.
Systems thinking
Feedback loops between metrics, incentives, and behavior lock the pattern in place.
Signals & signature
Inputs (activators)
Cloud + AI are complements; horse + car were substitutes.
Outputs (observable)
Strategic positioning is largely about which side of this you're on.
Behavioral signature
You see Complements & Substitutes when the explanation for a decision sounds reasonable but the outcome keeps repeating.
Behavioral molecules
Often combines with related Atlas entries — see the rail below.
Pathways · before
A goal, metric, or contract clause makes the behavior rational locally.
Pathways · after
Locally rational choices accumulate into a systemic distortion.
Domains where it shows up
  • Business
  • Leadership
  • Government
  • Healthcare
  • Education
  • Sales
  • Marketing
  • AI
  • Negotiation
  • Media
  • Public Policy
  • Relationships
Examples
Everyday
Cloud + AI are complements; horse + car were substitutes.
Modern
Strategic positioning is largely about which side of this you're on.
Historical
A pattern repeatedly documented since the foundational behavioral science literature on mental model.
Famous experiments
See the References block — primary papers in the Atlas link out to the original studies.
Design principles
How to leverage
Strategic positioning is largely about which side of this you're on.
How to reduce
Map every key partner and competitor as complement or substitute.
How to redesign
Map every key partner and competitor as complement or substitute.
The Perverse Incentive Lens™
How it's exploited
Organizations weaponize complements & substitutes — sometimes deliberately, often by accident — when metrics reward the symptom rather than the outcome.
Common perverse incentives
Volume metrics, short review windows, bonus cliffs, and contracts that pay on activity rather than impact.
Failure modes
When Complements & Substitutes dominates, teams optimize for the dashboard while the real outcome quietly degrades.
Incentive redesign
Map every key partner and competitor as complement or substitute.
Ethical considerations
Don't engineer complements & substitutes into customers, employees, or citizens as a manipulation tactic — design for informed choice instead.
Diagnostic questions
  • Where in our org would Complements & Substitutes most often show up unnoticed?
  • Which metric, ritual, or contract clause quietly rewards Complements & Substitutes?
  • If we removed every payoff for Complements & Substitutes, what behavior would replace it?
  • Who benefits when Complements & Substitutes persists — and who pays the cost?
Organizational warning signs
Metrics
A KPI is hit while the underlying outcome stalls or worsens.
Behaviors
People route around the rule rather than challenge it.
Language
'That's just how we do it here.' / 'The system requires it.'
Culture
Naming the pattern is treated as disloyalty.
Red flags
  • People defend the status quo using the language of complements & substitutes.
  • Decisions cluster around the easiest narrative rather than the strongest evidence.
  • New data changes the slide deck but not the decision.
  • Anyone naming the pattern is treated as the problem.
Intervention playbook
Immediate
Make the perverse payoff visible to the people creating it.
30-day
Run a small pilot that pays for the outcome, not the proxy.
Long-term
Rewrite the comp plan, contract, or ritual so the right behavior becomes the easy behavior.
AI considerations
Detect
Audit training data and reward signals for the same pattern this element describes.
Avoid amplifying
Don't optimize models on metrics that already encode the perverse incentive.
Counteract
Use the model to surface where the pattern is most active, then redesign the incentive — not the model.
Measurement
Metrics
Outcome-to-proxy ratio over time.
Assessment
The Incentives Lab III Diagnostic.
Survey
Calibrated pulse questions on rules vs. outcomes.
Behavioral signals
Where people work around the system.
Observational
Where the dashboard and the lived experience disagree.
Scientific evidence
Evidence grade
Synthesized from the behavioral science literature; see Atlas references.
Replication
Tracked in the Atlas as primary, replicated, or contested.
Intervention confidence
Moderate — patterns generalize, mechanisms vary by context.
Research consensus
Broad agreement on the pattern; ongoing debate on boundary conditions.
Known limitations
Local context, culture, and incentive structure all change the strength of the effect.
Open questions
How does Complements & Substitutes interact with AI-mediated decisions at scale?
References
Meta-analyses
Tracked in the Atlas registry.
Seminal authors
Kahneman, Tversky, Thaler, Ariely, Cialdini, Ostrom, Simon — and the field they built.
Cross references

Every Atlas entry is a node in a knowledge graph. See the related rail below to follow the connections.

Disciplinary layers

See Complements & Substitutes through 2 lenses

Each layer of the Incentives OS reframes this concept with its own thinkers, vocabulary, and diagnostic question.

Test yourself · 60 seconds

Do you actually know Complements & Substitutes?

Three quick questions. Result is saved into your review streak — come back when the term is due to lock it in.

Question 1 of 3Score: 0/3

Which best describes Complements & Substitutes?

Go deeper

Worked example, counter-example & concept map

On-demand AI analysis grounded in the Lab's research. Cached on your device after first run.

How this lands in you

Your nervous system has a region for this.

Primary region
Striatum & Nucleus Accumbens

When you encounter Complements & Substitutes, your striatum has built a reward association — and the next time the cue appears, it will push you toward the behavior whether you decide to or not.

Reward learning, habit formation, anticipation, craving, action selection. Habits live here. So do addictions. Variable rewards train this circuit faster than fixed ones.

See Striatum in the Brain Atlas →
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