← All writing · Essay · 8 min
2026-07-02 · by Selinay Parlak

The Psychology of Why We Take Notes on Some Things and Not Others

If you take notes on books or podcasts, you’ve noticed something strange: most of what you read or hear, you don’t mark. Then one sentence will make you stop, reach for a pen, write it down. The next hundred sentences pass through unmarked.

Why?

I’ve been thinking about this a lot because I built a note-taking app for podcasts (Margin), and the moment of deciding to mark is the entire point of the product. If I understand what makes someone reach for the button, I understand the product. If I don’t, I’m building blind.

What I’ve come to believe, partly from reading the psychology, partly from watching real Margin users, is that there are four specific triggers that make something note-worthy. Almost every note you’ve ever taken can be traced to one of them.

This essay names the four. I think it’s useful for note-takers (so you can be more deliberate about what you’re capturing), for writers (so you can write more capture-worthy sentences), and for podcasters (so you can produce moments listeners actually mark).

The four triggers

Here they are, in rough order of how often they trigger me:

  1. Self-relevance, “This is about me / my work / my situation.”
  2. Surprise, “I didn’t expect that.”
  3. Contradiction, “This is the opposite of what I believed.”
  4. Crystallization, “This says what I was already thinking but couldn’t articulate.”

Let me walk through each, then talk about what they mean for the people who make notes and the people who make content worth noting.

Trigger 1: Self-relevance

The biggest reason we mark something is that it speaks to us, to a problem we’re working on, a question we’ve been asking, an identity we hold.

The research backs this up. The self-reference effect (Rogers, Kuiper & Kirker, 1977, Journal of Personality and Social Psychology) is one of the best-replicated findings in memory research. When information is processed in relation to the self, it’s remembered dramatically better than information processed at a general semantic level. The brain treats me information differently.

This explains why podcast listeners who are founders mark different moments than podcast listeners who are designers, even on the same episode. The founder marks the moment about hiring; the designer marks the moment about tradeoffs. Both moments were available; one was self-relevant to each.

For note-takers: you’re going to find your library biased toward the questions you’re actively living with. This is healthy. The notes are a portrait of what you cared about during a particular window of your life. Don’t fight the self-relevance bias; lean into it.

For writers: if you want your work to be marked, name the reader’s situation specifically. Generic statements don’t trigger self-relevance. “If you’re a founder building your first product, this is the moment you’ll get the pricing wrong” triggers self-relevance. “Pricing is hard” doesn’t.

Trigger 2: Surprise

The second trigger is straightforward: things you didn’t expect. New information. Unexpected angles. Counterintuitive facts.

The neuroscience here is well-established. Surprise produces a dopamine signal that enhances memory consolidation. Wittmann et al. (2007) showed in Neuron that novelty-driven dopamine release in the substantia nigra is causally linked to improved encoding in the hippocampus. You remember the surprising thing because your brain literally gave it a memory boost.

This is why you mark the moment Howard Marks said “taking more risk doesn’t reliably increase return.” It’s the opposite of the conventional wisdom. The brain says: new pattern detected, save this.

For note-takers: the surprise notes are often your most important. They’re the ones most likely to update your model of how the world works. Pay special attention to them in review, they’re the seeds of belief revision.

For writers: if you want to be note-worthy, put your most counterintuitive claim in a sharp short sentence. The format matters. “Hiring on slope, not intercept” is markable because it’s surprising in eight words. The same idea expanded to a paragraph would be skipped.

Trigger 3: Contradiction

A subtle but powerful trigger is when something contradicts a belief you hold. Not just surprises you, actively conflicts with what you think.

This is psychologically different from pure surprise. Surprise opens a new pattern. Contradiction threatens an existing one. The brain responds with extra encoding effort because resolving the contradiction is now a task, you have to either update your view or articulate why you don’t.

Notes triggered by contradiction tend to feel different. They’re often accompanied by mental arguing. You mark the moment with “yes but…” in your head. The note is a marker of a fight you’re having internally.

For note-takers: these are the most generative notes for writing. The fight you’re having with the host is the seed of your own argument. Sontag’s marginalia is full of contradictions, she marked the sentences she disagreed with as often as the ones she agreed with.

For writers: if you want to provoke note-taking, contradict the reader’s working assumption. Not gratuitously, but where you actually believe the conventional view is wrong. The reader will mark the moment of contradiction, and they’ll either come around to your view or argue with you in their head, both of which deepen engagement.

Trigger 4: Crystallization

This is the most beautiful trigger, and the one I think about most.

Crystallization is when someone says what you were already thinking but couldn’t articulate. The relief of recognition. “Yes, that’s exactly what I was trying to say.”

The psychological mechanism here is closer to fluency than memory specifically. When information matches a half-formed idea you already had, your brain rewards the match with a feeling of cognitive ease. The match itself is pleasurable, and the pleasure motivates capture.

Crystallizations are valuable for a particular reason: they give you language for something you knew but couldn’t say. The note isn’t a new idea; it’s a new word for an old idea. But the new word changes how you can use the idea, you can now refer to it, share it, write from it.

This is why people mark quotes from writers like Susan Sontag, who didn’t always say new things but said them in unusually clean language.

For note-takers: crystallizations are gold for sharing. They’re the notes most likely to land when you tell a friend about them, because the friend probably also half-knew the idea and will appreciate the language. Twitter is full of crystallizations.

For writers: if you want to be quoted, write the sentence that names a feeling or idea the reader already had. The most quoted writers (Sontag, Joan Didion, Patrick Collison’s tweets) are unusually good at this. They give us the language for what we were trying to say.

What about emotion?

You might notice I haven’t included “emotional impact” as a separate trigger. Doesn’t sadness, awe, or anger make you take notes too?

I’d argue these are usually downstream of the four above. The story that makes you cry is doing so because it’s self-relevant. The fact that gives you awe is doing so because it’s surprising or contradictory. Emotion amplifies the four triggers, but I don’t think it’s a fifth trigger on its own.

(Reasonable people might disagree. Emotion-as-its-own-trigger is a defensible position. I’m just not convinced it’s independent of the four above.)

Implications for note-taking apps

This part is the self-interested one.

If you accept the four-triggers framework, certain design implications follow for a tool like Margin:

1. The capture interaction should be available in the exact moment of trigger. All four triggers fire in seconds. If the capture takes more than a few seconds, the moment passes. This is the case for press-and-hold from the lock screen, not “open the app and navigate to a recording screen.”

2. Brevity should be encouraged. The trigger lasts for one or two sentences of audio, and the note that captures it can be very short. “the moat = distribution thing” is enough. Apps that require long well-formed notes get fewer notes overall.

3. Anchoring is non-negotiable. Each of the four triggers comes from a specific moment in a specific episode. A note disconnected from its source is hard to validate or extend later. The episode and timestamp need to be attached automatically.

4. Review should help you see your patterns. Over time, your notes will skew toward one or two of the four triggers. Looking at your library and noticing “I mark mostly crystallizations, almost no contradictions” is itself informative, it tells you something about how you’re consuming.

I designed Margin around the first three. The fourth is what I want to build next: a way to review your notes that shows you which trigger pattern dominates your listening, and lets you intentionally shift it.

Implications for content creators

If you make content (write essays, host podcasts, produce videos), the four-triggers framework gives you a checklist:

A great podcast episode has all four. A great essay has at least three. A piece of forgettable content has none, it’s all true, all useful, all generic. Nothing triggers a mark.

The best content creators I follow, Patrick O’Shaughnessy, Shane Parrish, Dwarkesh Patel, produce work that lands all four triggers regularly. That’s why their work gets quoted, marked, shared. Not because they’re cleverer than average. Because they’re more triggering than average.

This is also a useful reframe for “go viral” thinking. Viral content is often note-worthy content. The mechanism that makes you Twitter-share a quote is the same mechanism that made you mark it in the first place: one of the four triggers fired.

The closing thought

I want to end with the meta-observation: the four triggers above are also the four ingredients of good thinking.

When you orient your reading and listening around finding self-relevant ideas, surprises, contradictions, and crystallizations, you’re not just collecting good notes, you’re doing the cognitive work that builds new beliefs.

The note-taking, in a sense, is downstream of the thinking. The pen reaching for the page is the muscle responding to a cognitive event that has already happened. The cognitive event is the real product. The note is just the receipt.

But the receipt matters. Without it, the event would be lost. So the small act of marking is the bridge between the thinking-that-happened and the thinking-that-becomes-something.

That’s why I built Margin. To make sure no note-worthy moment gets lost. And, though I didn’t fully realize this when I started, to make people more aware of which triggers fire most for them, so they can listen, read, and live a little more deliberately around what makes them think.

Selinay

Notes on the research

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