Samuel Johnson famously said that "a man ought to read just as inclination leads him, for what he reads as a task will do him little good." The same applies to annotation: marking done as a task — underlining text to feel like you are engaging — produces minimal benefit. Annotation done as genuine thinking on paper is among the most cognitively effective reading activities available.
The distinction is between non-generative annotation (highlighting, underlining, circling) and generative annotation (writing your own words: questions, summaries, disagreements, connections). The first is nearly equivalent to passive reading. The second is active reading made visible.
What the research shows
Dunlosky et al.'s (2013) comprehensive review of study techniques rated highlighting and underlining as low utility for long-term retention. The specific problem: highlighting is too easy. It requires only that you visually select text — not that you understand, evaluate, or process it.
Contrast this with what research shows about writing marginal notes: when students generate their own explanations and summaries in margins, comprehension and retention improve substantially. The mechanism is elaborative processing — generating your own language for an idea forces you to map the idea onto your existing knowledge structure, which creates a richer, more retrievable memory trace.
This is why the act of writing in margins is more effective than the same time spent re-reading. Re-reading adds familiarity (which is mistaken for learning). Marginal annotation adds a new encoding of the same idea in different words, which strengthens the memory trace through multiple encodings.
Non-generative annotation (what not to do)
Underlining entire paragraphs: If everything is important, nothing is. Underlining loses value when coverage is too broad to communicate priority.
Highlighting without comment: Creates the visual appearance of active reading without the cognitive substance. The fluency illusion applies here too — highlighted text looks processed when it may not have been.
Copying the author's words: Writing quotations in margins reproduces the original encoding rather than generating a new one. Summary in your own words is categorically different from transcription.
Generative annotation systems
The Mark Twain system (or any symbol system)
A small set of symbols applied consistently converts passive reading into rapid annotation without interrupting reading flow:
- ✓ or ★ : Important or agreed
- ? : Unclear, surprising, or requiring further thought
- ! : Striking, unexpected, or emotionally resonant
- × or ✗ : Disagree or find unconvincing
- → : Connects to something else (note the connection)
Symbols alone are non-generative — they still need accompanying brief notes for important passages. But they flag material for later, more intensive engagement without requiring you to stop and write at every turn.
The marginal summary method
After each section or paragraph, write a one-line summary in the margin in your own words. This is the most consistently effective annotation technique for academic material:
- Forces comprehension (you cannot summarise what you have not understood)
- Creates a retrieval cue visible without re-reading the text
- Enables rapid review by reading only marginal notes, not the full text
The test: could you understand your marginal note without re-reading the passage? If not, the note is too cryptic to be useful. If yes, you have created a compression of the passage that functions as both a comprehension check and a review resource.
Question generation
Writing a question about each major idea — "Why does the author argue X rather than Y?" "What evidence would undermine this?" "What are the limits of this claim?" — converts reading into dialogue. Questions:
- Establish purpose for subsequent paragraphs (you are reading to find the answer)
- Signal comprehension gaps (where you cannot form a question, you may not understand what is being claimed)
- Create retrieval cues for active recall — your question is a prompt that you can answer without looking at the text
This aligns with the question generation technique in our reading comprehension strategies guide.
Dialogue annotation
Writing your direct response to claims — "This contradicts X" / "I've noticed this in my own experience" / "This seems to assume Y is true" — is the annotation equivalent of self-explanation. It forces you to locate the claim in relation to your existing knowledge rather than appending it as an isolated fact.
Philosopher and novelist Umberto Eco described his annotation practice as "writing in the margins all the time" — questioning, connecting, arguing back. His notes were a conversation with the author rather than a record of the text.
Annotation for different purposes
For retention of a complex argument: Focus on marginal summaries and cross-reference notes ("same point as p. 47"). After finishing the chapter, review only the marginal notes — this is your retrieval practice session.
For critical engagement with academic material: Question generation and dialogue annotation. Every major claim gets either an agreement note ("supported by X") or a challenge note ("but what about Y?").
For pleasure reading of fiction: Lighter annotation — flagging resonant passages, noting character observations, writing brief reactions. The goal is not retention of every detail but capturing what made the book vivid so the reading journal entry is richer.
For technical manuals and reference material: Structure-focused annotation — noting where to find specific information, flagging cross-references, writing the key procedure or definition in the margin for rapid retrieval.
Digital annotation
For RSVP reading tools and ebooks, native annotation features (Kindle highlights and notes, Apple Books annotations, PDF markup) provide the same function. The key is discipline about what you annotate:
- Use notes (written text), not just highlights
- Write your summary in the note field, not just highlight the original
- Review your annotations in the annotations view after finishing, which provides a rapid retrieval practice session
One limitation of RSVP reading (on warpread.app and similar tools) is that it does not support inline annotation — the forward-only pace means annotation must happen between sessions rather than mid-flow. The reading journal technique, or a companion notes file, substitutes effectively for marginal notes when using RSVP.
Building an annotation practice
The risk with a structured annotation system is that it becomes a burden that discourages reading. The goal is never annotation for its own sake — it is annotation in service of understanding and retention.
Start with one technique: the marginal summary. After each page or section, write one sentence in the margin in your own words. Once this is habitual, add question generation for material you want to engage with critically.
For readers using RSVP, keep a companion document open during reading sessions and write brief notes after each chapter — same cognitive function as marginal annotation, adapted to the forward-only RSVP format.
Combine annotation with active recall reading for a complete active reading system.
Read actively on warpread.app — free RSVP reader
References
- Dunlosky, J., Rawson, K.A., Marsh, E.J., Nathan, M.J., & Willingham, D.T. (2013). Improving students' learning with effective study techniques. Psychological Science in the Public Interest, 14(1), 4–58.
- Chi, M.T.H., de Leeuw, N., Chiu, M.H., & LaVancher, C. (1994). Eliciting self-explanations improves understanding. Cognitive Science, 18(3), 439–477.
- Mueller, P.A., & Oppenheimer, D.M. (2014). The pen is mightier than the keyboard. Psychological Science, 25(6), 1159–1168.
- Adler, M.J., & van Doren, C. (1972). How to Read a Book. Simon & Schuster.
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