The 1-3-5 Rule is each day: one big thing, three medium things, five small things. Nothing else counts. It sits in the Cognition dimension (COG) of the Human Behavior Taxonomy™ as element HBT-COG-0667, within the Decision family. The core principle: each day: one big thing, three medium things, five small things. Nothing else counts. 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
Each day: one big thing, three medium things, five small things. Nothing else counts.
Plain-English Definition
Each day: one big thing, three medium things, five small things. Nothing else counts.
Feynman Explanation
If you accomplished nine things today and the big one wasn't one of them, you had a busy zero.
Core Principle
Each day: one big thing, three medium things, five small things. Nothing else counts.
Mechanisms
Pending editorial review.
Each day: one big thing, three medium things, five small things. Nothing else counts.
Pending editorial review.
Pending editorial review.
Pending editorial review.
Pending editorial review.
Calendar design and executive focus.
Inputs (Triggers)
Pending editorial review.
Outputs (Behaviors)
Pending editorial review.
Behavioral Signature
If you accomplished nine things today and the big one wasn't one of them, you had a busy zero.
Examples
- A daily-prioritization heuristic popularized through productivity manuals.
- Calendar design and executive focus.
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: each day: one big thing, three medium things, five small things. Nothing else counts. You can recognize it in the field by its signature: if you accomplished nine things today and the big one wasn't one of them, you had a busy zero. 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, calendar design and executive focus. It is amplified whenever calendar design and executive focus. Inside organizations that shows up as calendar design and executive focus. 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 write the one before you check email. Once you read inbound, the one is somebody else's. Treat it as infrastructure. Once you can see it in your own system, most of the argument about culture resolves itself.
Famous Experiments
Pending editorial review.
Design Principles
- Write the one before you check email. Once you read inbound, the one is somebody else's.
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.
- Write the one before you check email. Once you read inbound, the one is somebody else's.
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.
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.
Decisions are constrained by available information, cognitive limits, and time.
The ability to focus on one voice in a noisy environment.
Where The 1-3-5 Rule 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 The 1-3-5 Rule
- What is The 1-3-5 Rule?
- The 1-3-5 Rule is each day: one big thing, three medium things, five small things. Nothing else counts. It sits in the Cognition dimension (COG) of the Human Behavior Taxonomy™ as element HBT-COG-0667, within the Decision family. The core principle: each day: one big thing, three medium things, five small things. Nothing else counts. 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 The 1-3-5 Rule?
- Calendar design and executive focus. The Incentives Lab catalogs everyday, organizational, and historical instances of this element on its Human Behavior Taxonomy™ page (HBT-COG-0667).
- How is The 1-3-5 Rule exploited?
- Calendar design and executive focus.
- How do you design around The 1-3-5 Rule?
- Write the one before you check email. Once you read inbound, the one is somebody else's.
- Which behavioral dimension does The 1-3-5 Rule belong to?
- The 1-3-5 Rule is classified in the Cognition dimension (COG) of the Human Behavior Taxonomy™, family "Decision", class "Mental Model". Its permanent identifier is HBT-COG-0667 and its evidence grade is B.