Today I Learned Journal is daily one-line capture of the single most important thing you learned that day. It sits in the Cognition dimension (COG) of the Human Behavior Taxonomy™ as element HBT-COG-0675, within the Learning family. The core principle: daily one-line capture of the single most important thing you learned that day. 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
Daily one-line capture of the single most important thing you learned that day.
Plain-English Definition
Daily one-line capture of the single most important thing you learned that day.
Feynman Explanation
If nothing went in the journal, nothing went in your head either.
Core Principle
Daily one-line capture of the single most important thing you learned that day.
Mechanisms
Pending editorial review.
Daily one-line capture of the single most important thing you learned that day.
Pending editorial review.
Pending editorial review.
Pending editorial review.
Pending editorial review.
Cheapest compounding learning system available; near zero overhead.
Inputs (Triggers)
Pending editorial review.
Outputs (Behaviors)
Pending editorial review.
Behavioral Signature
If nothing went in the journal, nothing went in your head either.
Examples
- TIL journals used by engineers, founders, and lifelong learners.
- Cheapest compounding learning system available; near zero overhead.
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: daily one-line capture of the single most important thing you learned that day. You can recognize it in the field by its signature: if nothing went in the journal, nothing went in your head either. 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, cheapest compounding learning system available; near zero overhead. It is amplified whenever cheapest compounding learning system available; near zero overhead. Inside organizations that shows up as cheapest compounding learning system available; near zero overhead. 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 add a 60-second end-of-day prompt: 'What's today's TIL?'. The test of any redesign here is simple: after the change, can you name what the organization is now doing less of? If not, the payoff structure did not actually move.
Famous Experiments
Pending editorial review.
Design Principles
- Add a 60-second end-of-day prompt: 'What's today's TIL?'
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.
- Add a 60-second end-of-day prompt: 'What's today's TIL?'
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.
Giving up after repeated exposure to uncontrollable negative events.
Learners build knowledge by integrating new experience with existing mental structures — not by passive reception.
Targeted reps at the edge of your ability, with fast feedback, on a specific weakness.
Four dimensions of learner preference: Active/Reflective, Sensing/Intuitive, Visual/Verbal, Sequential/Global.
Four learner preferences derived from Kolb: Activist, Reflector, Theorist, Pragmatist.
Four-stage cycle: Concrete Experience → Reflective Observation → Abstract Conceptualization → Active Experimentation.
Performance improves with practice, but gains slow over time.
A deliberately curated set of people, sources, and feedback loops you draw on to learn faster than alone.
Default identity shift: you read, watch, and listen as a future teacher, not a passive consumer.
Preparing to teach a concept forces deeper encoding than passively studying it.
Pulling information out of memory cements it better than passively re-reading it.
Bloom-stacked curriculum that pairs passive online content with facilitated, experiential, and implementation phases.
Where Today I Learned Journal 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 Today I Learned Journal
- What is Today I Learned Journal?
- Today I Learned Journal is daily one-line capture of the single most important thing you learned that day. It sits in the Cognition dimension (COG) of the Human Behavior Taxonomy™ as element HBT-COG-0675, within the Learning family. The core principle: daily one-line capture of the single most important thing you learned that day. 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 Today I Learned Journal?
- Cheapest compounding learning system available; near zero overhead. The Incentives Lab catalogs everyday, organizational, and historical instances of this element on its Human Behavior Taxonomy™ page (HBT-COG-0675).
- How is Today I Learned Journal exploited?
- Cheapest compounding learning system available; near zero overhead.
- How do you design around Today I Learned Journal?
- Add a 60-second end-of-day prompt: 'What's today's TIL?'
- Which behavioral dimension does Today I Learned Journal belong to?
- Today I Learned Journal is classified in the Cognition dimension (COG) of the Human Behavior Taxonomy™, family "Learning", class "Mental Model". Its permanent identifier is HBT-COG-0675 and its evidence grade is B.