In 1885, Hermann Ebbinghaus discovered the forgetting curve: without review, we forget 70% of new information within 24 hours. But spaced repetition — reviewing material at increasing intervals — can flatten that curve dramatically.
The science is clear. A 2006 meta-analysis in Psychological Science in the Public Interest found that distributed practice (spacing) is one of the most effective study techniques, outperforming highlighting, re-reading, and summarization.
How it works: Each time you successfully recall information, the memory trace strengthens and the optimal review interval increases. First review after 1 day, then 3 days, then 7 days, then 14 days. The key is retrieving the information, not just seeing it again.
Cognify uses a modified Leitner box algorithm to schedule review questions. When you miss a question, it moves to a shorter review interval. When you get it right, the interval extends. This means you spend more time on what you're actually forgetting.
Practical tip: Don't try to cram everything into one session. Three 20-minute sessions spread across a week produce better long-term retention than one 60-minute marathon. Your brain consolidates memories during sleep, so studying before bed and reviewing in the morning is especially effective.