The forgetting curve: why we forget, and how to remember longer
In the 1880s, one German psychologist memorized thousands of nonsense syllables to measure forgetting. What he found still shapes how we learn today.
Why can you remember a song from ten years ago, but not what you read in a meeting last Tuesday? The answer starts with a German psychologist named Hermann Ebbinghaus, who in the 1880s did something nobody had tried before: he measured forgetting.
The experiment
Ebbinghaus memorized lists of nonsense syllables like “DAX”, “BOK” and “ZUP”, chosen so they’d have no meaning to help him. Then he tested himself after different delays: twenty minutes, an hour, a day, a month. He measured how much time it took to relearn each list, which showed how much had survived. He published the results in 1885, and the shape he found became known as the forgetting curve.
What the curve shows
Forgetting is fastest right after learning, then slows down. A large share of new, unreviewed material fades within the first day. What survives the first few days tends to last much longer. Ebbinghaus’s nonsense syllables were a worst case; meaningful information fades more slowly. But the shape, steep at first and then flattening, has been found again and again.
Ebbinghaus also noticed something crucial: each time you relearn something, it fades more slowly. That’s the foundation of spaced repetition.
Why we forget
It was never stored well. Much “forgetting” is really poor encoding: the information passed through working memory without being processed deeply. Other memories get in the way. Similar information competes, like a new phone number interfering with your old one. The retrieval cue is missing. The memory is there, but nothing brings it back; the tip-of-the-tongue feeling is a classic example. It fades without use. Connections that are never used grow weaker.
Forgetting isn’t a flaw. Your brain is constantly deciding what’s worth keeping, and most of what you encounter each day genuinely isn’t.
Five ways to flatten your forgetting curve
1. Review at spaced intervals. Review after a day, then a few days, then a week. Each review resets the curve at a slower rate of decline.
2. Test yourself. Trying to recall something strengthens it far more than rereading it. This is called the testing effect or retrieval practice.
3. Make it meaningful. Connect new information to what you already know. Meaning is why real words fade slower than nonsense syllables.
4. Sleep on it. Sleep helps consolidate new memories. See how sleep affects memory.
5. Learn it well the first time. Pay full attention, and practice a little beyond the point where you first get it right.
See forgetting in action
Try this quick number test, then try to recall the last sequence in five minutes. You’ll likely find it’s gone, which is exactly what the curve predicts for information you never reviewed.
Frequently asked questions
What is the forgetting curve?
A graph showing how memory for new information fades over time. It drops steeply at first, then levels off. It was first described by Hermann Ebbinghaus in 1885.
How fast do we forget?
Much of what we learn is lost within the first day if we never review it. The exact amount depends on how meaningful the material is and how well it was learned.
How do you beat the forgetting curve?
Review information at spaced intervals, test yourself instead of rereading, connect new information to what you already know, and sleep well.