A 2013 meta-analysis by Dunlosky et al. reviewed 10 study techniques on two dimensions: effectiveness and evidence base. The results upended what most students have been taught.
Here's the ranked evidence — from most to least effective.
Tier 1: High-Utility Techniques (Strong Evidence)
1. Practice Testing (Retrieval Practice)
Effectiveness: Very high
Taking practice tests — even before you feel "ready" — consistently outperforms all other study methods for long-term retention.
Why it works: Retrieving information from memory strengthens the memory trace more than reviewing the information again. The "testing effect" is one of the most replicated findings in cognitive psychology.
How to implement:
- Use flashcards (Anki's spaced repetition algorithm is optimal)
- Take past exams under timed conditions
- Close the book and write everything you remember
- Use the Cornell note method (questions in margin, answers covered)
Evidence: Students who tested themselves retained 50% more information after 1 week compared to students who re-read the same material three times.
2. Distributed Practice (Spaced Repetition)
Effectiveness: High
Spreading study sessions over time ("spacing") dramatically outperforms massed practice ("cramming") for long-term retention.
The spacing effect is strong even with the same total study time:
- 3 hours crammed in one session vs.
- 1 hour each over 3 days
The distributed version produces 40-50% better retention after 1 week.
Optimal spacing intervals (based on forgetting curve research):
- New material: review at 1 day, 3 days, 7 days, 14 days, 30 days
- Anki automates this based on your performance
Tier 2: Moderate-Utility Techniques
3. Elaborative Interrogation
Effectiveness: Moderate
Asking "why" and "how" questions about material. Instead of reading "plants use photosynthesis," ask "WHY do plants use photosynthesis instead of another process?"
Evidence: Students using elaborative interrogation outperform control groups by 20-30% on comprehension tests.
4. Self-Explanation
Effectiveness: Moderate
Explaining concepts in your own words, step-by-step, as you learn them. The "Feynman Technique": if you can't explain it simply, you don't understand it yet.
How to implement: After reading a section, close the book and explain the concept to an imaginary student. Note where you get stuck.
Tier 3: Low-Utility (Despite Widespread Use)
5. Summarization
Effectiveness: Low (for most students)
Writing summaries helps only when students have been trained in effective summarization. Most untrained summarization is too shallow to improve learning.
6. Highlighting and Underlining
Effectiveness: Very low
The most common study technique is among the least effective. Highlighting creates an illusion of processing — you're marking text, not engaging with it.
Why it feels useful: Highlighting is easy, creates visible progress, and provides the subjective feeling of learning. This feeling is misleading.
7. Re-Reading
Effectiveness: Very low
Re-reading produces a "fluency illusion" — the material feels familiar so it feels learned. Familiarity and retrievability are not the same thing.
Time Investment vs. Learning Gain
| Technique | Hours to see effect | Learning gain per hour |
|---|---|---|
| Practice testing | 1 hour | Very high |
| Spaced repetition | 30 minutes/day | Very high |
| Elaborative interrogation | 2 hours | Moderate |
| Re-reading | 3 hours | Very low |
| Highlighting | 2 hours | Very low |
The Optimal Study Session
Based on the evidence:
- Read new material once (don't re-read)
- Generate questions about what you read (elaborative interrogation)
- Close the book, retrieve what you remember (practice testing)
- Check what you missed and note it for the next session
- Schedule the next session based on spacing intervals
Total time per concept: 30-45 minutes for new material, 10 minutes per review session.
Use the Study Time Calculator to plan your optimal study schedule based on your exam date and material volume.