It turns out that forgetting is an essential part of learning.

When learners (or educators) talk about “teaching to the test” and “cramming,” they are describing massed learning—attempting to learn and remember a mass of information in a single session or a few closely spaced sessions. That “learning” is measured by the learners’ ability to recall that information on a test or other assessment given in the same context (classroom) and generally within a short time frame, such as a semester.

For long-term retention or solid learning that can be applied in contexts and to problems different from those posed in the study session, a different approach to learning is needed: spaced learning.However, as many learners know only too well, after “cramming,” the learning doesn’t tend to stick.

Spaced learning can be applied to both inductive learning, which emphasizes critical thinking, problem-solving, and analysis; and deductive learning, which presents rules and examples. It can enable the long-term recall of facts as well as deeper understanding of concepts. And it’s based, in part, on the mechanisms in the brain that help people remember some information while forgetting other information.

Ebbinghaus and the “forgetting curve”

Beginning in 1885, Dr. Hermann Ebbinghaus, a German psychologist, conducted a series of experiments on memory, using himself as a subject. He memorized lists of nonsense syllables and tested his recall of those syllables.

Some of his findings have morphed into a concept known as the “forgetting curve,” which relates to the effect of time and repetition on the ability to recall information. The forgetting curve shows the drop-off in recall over time following learning. The steepest part of the forgetting curve is immediate: Learners will forget up to half of new information within an hour or so of training; after a week, they’ll have forgotten nearly everything. But obviously, people do learn and retain information, so the curve is not the end of the story.

Forgetting is a key element of the learning process because it helps the brain sort important from trivial information; in this age of information overload, a filtering process is essential. “The ability to retrieve and generate information that is wanted, relevant, and appropriate is made possible by the ability to inhibit, and thus forget, information that is unwanted, irrelevant, and inappropriate,” according to researcher Benjamin Storm.