

Chapter 1
The man who forgot on purpose
Chapter 2
The physical brain under construction
Chapter 3
From cardboard boxes to supercomputers
Chapter 4
Spaced repetition in the wild
Ch 1 · The man who forgot on purpose

duolingo To study memory without bias, Hermann Ebbinghaus spent months memorizing 2,300 nonsense syllables like WID and ZOF to a metronome.
Quiz
What type of letter combinations did Hermann Ebbinghaus invent to study memory in its purest form?

duolingo The non-linear forgetting curve shows how quickly unreviewed memories slip away.
Quiz
According to Ebbinghaus's data, about how much of his relearning savings was lost after just one hour?
Fun Fact
Ebbinghaus's metronome: Ebbinghaus read his nonsense syllables to the steady beat of a metronome set at 150 beats per minute to keep his study pace perfectly consistent.
Quiz
If it took Ebbinghaus 10 minutes to learn a list the first time, and 6 minutes to relearn it later, what was his savings percentage?
Glossary
forgetting curve (noun)
A graph depicting the rate at which newly learned information fades from memory when not actively reviewed. In 1885, German psychologist Hermann Ebbinghaus plotted this mathematical decay after testing his recall of nonsense syllables.
A graph depicting the rate at which newly learned information fades from memory when not actively reviewed. In 1885, German psychologist Hermann Ebbinghaus plotted this mathematical decay after testing his recall of nonsense syllables.
Quiz
What did the 2015 replication study conclude about Ebbinghaus's original 1885 findings?
Quiz
Which scientific journal published the 2015 study that successfully replicated Ebbinghaus's original forgetting curve?