The Curve of Forgetting




The curve of forgetting states that there is a correlation between the amount of time between learning material and reviewing it and how well one preforms on a test. This theory states that if we review material that we learned that day, we will remember up to 80% of what we learned.

It had never occurred to me before that we can actually lose information after a few days, but according to this study, if we review material that we learned in the same day, we will remember it 80% of it. A longitudinal study that was conducted over 60 years starting in 1880 proved this theory, and a replicate of this randomized control study conducted recently proved the findings to be correct. In this study, they had a random group of people memorize a list of vocabulary and relearn the list either 20 minutes later, one hour later, nine hours later, one day later, two days later, six days later, or 31 days later. The results show that the people who reviewed the material that same day and studied it over a longer period of time answered more accurately than the people who studied days later.



This experiment proved that the sooner we study after we learn the material, the less time we will have to put in studying later on, and the more accurate we will perform on our tests.

Although there is no mechanism for this hypotheses stated in this study, since the data was replicated very similarly to the previous study, the results can be viewed as legitimate. This replicated results also can prove a correlation between the time between learning the material and how much we remember from it.



Another study, though, provides a theory for the mechanism of forgetting in our short-term memory. According to the study, memory, as well as forgetting, are controlled through the balance between two different proteins, called kinases and phosphatases. Because memory is controlled by kinases and forgetting are controlled by phosphatases, scientists believe that the two combined leads to forgetting in our short-term memory.

Another theory of why we forget is the decay theory of forgetting. This theory states that we forget because a certain amount of time has passed since we learned something. It also states that we can only remember the information we just learned after 15 to 30 seconds, unless we “rehearse” or study the information later. This also supports and is in agreement with the curve of forgetting because they both state that the longer we go after learning the information, the more we will forget it.

After I read these two studies and researched this theory, I was pretty discouraged. Who has the time to sit down and study what they learned day after day and week after week? According to Jim Roth, though, the more times we learn new information, and the more time we “touch” this information (like review and study it), the better it will become part of our permanent memory, such as our name or our phone number. He also suggested using flashcards whenever we can. This way the information is more accessible and we can bring them with us wherever we go. (Not that we’ll bring them with us everywhere we go, but you know what I mean.) This also means that the information will trickle into our brains a little at a time, which is the best way to learn, according to Jim Roth.

4 thoughts on “The Curve of Forgetting

  1. Margaret Eppinger

    This is a very well written and synthesized post. Great job! As for the actual science, it makes me a bit unhappy, since I have a tendency to procrastinate. As a result, I often cram for the exam, so to speak. Unfortunately, this evidence seems to show a clear link that waiting to study material is not a good idea. I think it’s also interesting to note that there have also been studies done that test that difference between studying ahead of time and spreading it out over a period of days and cramming at the last minute. Here is an article by BBC that discusses this difference: In the study the article cites, 90% of the participants performed better if they studied ahead of time instead of cramming. This research supports the idea in your post that we should study something the day we learn it, then continue to refresh ourselves on the material. I think combining both approaches would be a very effective way to study.

    1. Lauren Hile Post author

      Wow, that’s a great article! It makes me think about how Andrew told us that most of the time our intuition is incorrect—as in we think we know something and we really don’t. I’ve taken plenty of tests where I thought I “knew” the material, as in I could recognize it if I saw it, but I couldn’t recall it. It’s interesting to know that the recall part of our brains are quite different than the visual part and don’t actually relate at all to each other. Here’s another article with tools for studying better, including apps that help test us on material, because that is the best way to learn, as it is recall.

  2. Patrick James Mcgovern

    This is very thorough and thoughtful article, well done! I enjoyed learning more about this concept and it helps me to identify some bad (or non-existent) habits in my studying.

    But my question is, do you think this changes depending on the material being understood? I don’t see this being applied across the board for all kinds of education. I feel like there are too many human differences and too many course differences to allow for anyone anywhere to improve by same day studying.

    I know for me, I am a writing student that can read and address literature while producing it well enough, but when I come out of a math class or a Spanish class I feel like a 5 year old. I think maybe this is just the sort of thing that needs to be focused on weak areas, and not used for certain classes that don’t require memorization.

    1. Lauren Hile Post author

      I agree with you. I think that this kind of studying really only applies to courses that require memorization for tests. In my experience, when trying to learn a language it really did help creating flashcards (either traditional ones or ones on quizlet) that same day and reviewing them every few days until the test, but for courses that don’t require much memorization, such as literature classes, I’m not sure how much help it will be.

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