Dunbar's Number is ~150 — the cognitive limit on stable social relationships. It sits in the Cognition dimension (COG) of the Human Behavior Taxonomy™ as element HBT-COG-0254, within the Systems family. The core principle: ~150 — the cognitive limit on stable social relationships. 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
~150 — the cognitive limit on stable social relationships.
Plain-English Definition
~150 — the cognitive limit on stable social relationships.
Feynman Explanation
Above 150, you have a directory, not a tribe.
Core Principle
~150 — the cognitive limit on stable social relationships.
Mechanisms
Pending editorial review.
~150 — the cognitive limit on stable social relationships.
Pending editorial review.
Pending editorial review.
Pending editorial review.
Pending editorial review.
Scaling org design must account for the 150-person inflection.
Inputs (Triggers)
Pending editorial review.
Outputs (Behaviors)
Pending editorial review.
Behavioral Signature
Above 150, you have a directory, not a tribe.
Examples
- Org structures that retain coherence below ~150, fragment above.
- Scaling org design must account for the 150-person inflection.
Pending editorial review.
Original analysis from The Incentives Lab — how this element behaves inside real payoff structures.
Why this element matters to incentive design
The mistake with this element is treating it as irrationality. It is almost always a rational response to a payoff nobody wrote down. The mechanism underneath it is straightforward: ~150 — the cognitive limit on stable social relationships. You can recognize it in the field by its signature: above 150, you have a directory, not a tribe. 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, scaling org design must account for the 150-person inflection. It is amplified whenever scaling org design must account for the 150-person inflection. Inside organizations that shows up as scaling org design must account for the 150-person inflection. 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 design deliberate sub-tribes when crossing Dunbar's threshold. 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
- Design deliberate sub-tribes when crossing Dunbar's threshold.
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.
- Design deliberate sub-tribes when crossing Dunbar's threshold.
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.
Combining substances to create a new material stronger than its parts.
A single constraint limits the throughput of an entire system.
A system's throughput is constrained by its single slowest step.
Small visible disorders signal that bigger ones will be tolerated.
Adding manpower to a late software project makes it later.
Adding people to a late project makes it later.
A substance that speeds up a reaction without being consumed.
Nonlinear systems are highly sensitive to initial conditions.
Inputs combine under conditions to produce new outputs — sometimes irreversibly.
Software architecture mirrors org structure.
Working together has a cost that scales with the number of people.
The threshold at which a system becomes self-sustaining.
Where Dunbar's Number 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.
- 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 Dunbar's Number
- What is Dunbar's Number?
- Dunbar's Number is ~150 — the cognitive limit on stable social relationships. It sits in the Cognition dimension (COG) of the Human Behavior Taxonomy™ as element HBT-COG-0254, within the Systems family. The core principle: ~150 — the cognitive limit on stable social relationships. 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 Dunbar's Number?
- Scaling org design must account for the 150-person inflection. The Incentives Lab catalogs everyday, organizational, and historical instances of this element on its Human Behavior Taxonomy™ page (HBT-COG-0254).
- How is Dunbar's Number exploited?
- Scaling org design must account for the 150-person inflection.
- How do you design around Dunbar's Number?
- Design deliberate sub-tribes when crossing Dunbar's threshold.
- Which behavioral dimension does Dunbar's Number belong to?
- Dunbar's Number is classified in the Cognition dimension (COG) of the Human Behavior Taxonomy™, family "Systems", class "Mental Model". Its permanent identifier is HBT-COG-0254 and its evidence grade is B.