In the field of psychology the term forgetting curve describes how the ability of the brain to retain information decreases in time.
Hermann Ebbinghaus was the first to study the forgetting behavior in an experimental, scientific way. In his groundbreaking research he studied on himself the memorization and forgetting of nonsense three letter words. Examples of such words are KAF or WID. Words, which had a meaning or easily alluded to a known word were excluded. (See for more details Ebbinghaus memory experiments).
Ebbinghaus performed a series of tests on himself over various time periods. He then analyzed all his recorded data to find the exact shape of the forgetting curve. He found that forgetting is exponential in nature.
Ebbinghaus published his findings in 1885 in his book “Über das Gedächtnis (Memory: A Contribution to Experimental Psychology)”.
At the beginning your retention is 100% since this exactly the point in time when you actually learned the piece of information. As time goes on the retention drops sharply down to around 40% in the first couple of days.
The forgetting curve is exponential. That means that in the first days the memory loss is biggest, later (as you can see in the forgetting curve above) you still forget but the rate at which you forget is much, much slower.
The forgetting curve clearly shows that in the first period after learning or reviewing a piece of information we forget most!
The speed with which we forget any information depends on a number of different factors:
- How difficult is the learned material?
- How easy is it to relate the information with facts, which you know already?
- How is the information represented?
- Under which condition are you learning the material?
- Are you stressed?
- Are you fully rested and have you slept enough?
While all individuals differ in their capacity to learn and retain information the shape of the forgetting curve for base tests (such as nonsensical words) is nearly identical.
Thus the differences in learning capacities come from different acquired learning behaviors. Some individuals are able to transform the piece of information to a memory representation that is more suitable for them (for example audio oriented learners or visually oriented learners). Also some people have naturally a better capacity to use memory hooks and other mnemonic techniques to remember more easily and relate to information, which they know already.
However these techniques can be learned and applied by anybody.
What can you do to improve your memory?
- Learn to connect new information with what you know already. Use memory hooks and other mnemonic devices to represent the new information in terms of already familiar concepts.
- Activate the information in regular, spaced intervals. It is important that the recall is active, that is, you should not just re-read the new information but reply to a question about the new information. Like that your brain will be forced to activate the memory and to deepen the neural connections.
- Use spaced repetitions. Spaced repetition (in particular spaced repetitions software) enables you to calculate the exact time when you profit most from a review: the time just before forgetting.
The image shows what happens to the learning curve after your review the piece of information several times. Every time you repeat it your retention rate goes back to 100% since you just reviewed the information. And every time forgetting sets in in the very same way as if you learned the item only once. What is however drastically different is the speed at which you forget. As you can see in the image the forgetting curve becomes flatter and less steep with every additional review, provided the review is made at the correct time.
Every time you activate and review the new information the memory traces become stronger. The stronger the memory the longer you are able to recall the information. Therefore the learning curve and the corresponding retention rate for that piece of information becomes flatter. This means that the interval for the next repetition becomes longer. For some information the interval can become several years.
Learning from the forgetting curve – how not to learn
Typical cramming sessions in school, for example quickly learning vocabulary lists before a test are usually useless from a long term perspective. Most students don’t remember more than 10-20% after about half a week. The effort you made to learn these lists was in vain — you lost 80-90% of the learned material.