What Research Actually Says About Memorization and Retention

Most study advice is vibes. Here's what the research actually shows.

Ebbinghaus (1885): The Forgetting Curve

Hermann Ebbinghaus memorized nonsense syllables and measured his own decay rate. The result: within 20 minutes, 42% of learned material is gone. Within 24 hours, 67%. Within a month, nearly 80%.

But here's the part people miss: each re-learning session made the curve shallower. The spacing effect — reviewing material at increasing intervals — was discovered in the same experiment. Ebbinghaus found that distributing study over time produced better retention than cramming, by a factor of nearly 2x.

The Testing Effect (Roediger & Karpicke, 2006)

This is the big one. Students studied a passage, then either:

  • Re-read it (the control group)
  • Took a free recall test (the experimental group)

Results after one week: the testing group remembered 50% more than the re-reading group. After re-reading, students felt more confident. After testing, they actually knew more.

The mechanism: retrieval strengthens memory traces. Every time you pull information out of your brain, you make the path easier to find next time. Re-reading doesn't trigger this — it just creates familiarity, which is easily confused with mastery.

Interleaving vs Blocking (Rohrer & Taylor, 2007)

Students practiced math problems in two formats:

  • Blocked: 10 problems of Type A, then 10 of Type B
  • Interleaved: A, B, A, B, mixed randomly

During practice, the blocked group felt more confident and performed better. On the final test a week later, the interleaved group scored 43% higher.

Why: interleaving forces your brain to identify which strategy to use, not just execute a known pattern. For tax exam prep, this means mixing topic sections rather than grinding one topic at a time.

Spacing Effect Meta-Analysis (Cepeda et al., 2006)

Reviewed 317 experiments on distributed practice. Optimal spacing interval: 10-20% of the retention interval. If you want to remember something for 30 days, review it every 3-6 days. For 365 days, review every 36-73 days.

Most students space too tightly (reviewing daily) or too loosely (reviewing never). The sweet spot is uncomfortable — you should feel like you're almost forgetting the material.

What This Means for EA Exam Prep

  1. Stop re-reading. It feels productive but produces the worst retention per hour invested.
  2. Test yourself before you feel ready. The struggle is the mechanism, not a sign of failure.
  3. Mix your topics. Don't grind filing statuses for a week then switch to deductions. Interleave.
  4. Space your reviews at increasing intervals. Day 1, Day 3, Day 10, Day 30, Day 90.

EA Coach implements all four of these principles automatically — spaced repetition scheduling, active recall via flashcard testing, and interleaved topic mixing. The algorithm is the same one medical students use to retain thousands of facts over years.

The research is not ambiguous. The methods that feel easiest (re-reading, cramming, blocking) produce the worst results. The methods that feel harder (testing, spacing, interleaving) produce durable knowledge. Choose accordingly.