Forgetting Helps You Remember: Why Spaced Learning Works

It turns out that forgetting is an essential part oflearning.

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

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

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

Ebbinghaus and the “forgetting curve”

Beginning in 1885, Dr. Hermann Ebbinghaus, a Germanpsychologist, conducted a series of experiments on memory, using himself as asubject. He memorized lists of nonsense syllables and tested his recall ofthose syllables.

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

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

Spaced learning or spaced retrieval practice can reshape theforgetting curve and help learners control which information is retained andwhich is discarded. When a person periodically practices reviewing informationand retrieving that information—by solving problems, applying concepts,answering test questions, or using other forms of recall or assessment—itreinforces the learning. At the same time, information that is not recalledtends to fade from the learner’s memory. The intervals between repetitions orrecall attempts can grow larger over time, as the learner’s memory of theinformation becomes stronger; the information eventually becomes part oflearners’ long-term memories.

Other factors can influence learning and memory, of course:A strong emotion can cement memories of an event—like the September 11 attackson the US World Trade Center or the assassination of President Kennedy in 1963—inpeople’s minds forever, including minute details, such as where they were orwhat they were wearing. But that type of emotional impact is rare and tough toplan. Educators seeking to make eLearning impactful and sticky can more easilyapply the science underlying spaced learning to improve retention.

The goal: Long-term retention

Short-term recall—regurgitating information for a test—israrely the goal of eLearning. Employers are looking for long-term retention ofskills and knowledge that will lead to a boost in performance.

In an article published in Change, “Applying the Science of Learning to the University and Beyond,” as well as in a book and conferenceof the same name, Diane Halpern and Milton Hakel state that “the single mostimportant variable in promoting long-term retention and transfer is ‘practiceat retrieval.’ … Simply stated, information that is frequently retrievedbecomes more retrievable.”

It’s a complex puzzle: “Principles of learning are difficultto discuss in isolation because learning activities that occur at differenttimes—at the point of initial learning, during the retention interval, and at thepoint of recall—are all interdependent. They work together to determine what isremembered at some point in the future, well after the first recall test isadministered. According to standard ‘memory trace’ theories of how we remember,the act of remembering strengthens some memory traces and weakens—or at leastfails to strengthen—others,” according to Halpern and Hakel.

In addition, processing information in different formats anddifferent contexts aids learning and retention, as does being asked to presentinformation in a different way than it was learned, whether that is a differentmodality or applying it to a new problem. “When learning occurs under variedconditions, key ideas have ‘multiple retrieval cues’ and thus are more‘available’ in memory,” according to Halpern and Hakel. And, they add, ifeducators or trainers are simply teaching to the test, lecture or presentationof information to passive learners might suffice, but “it is one of the worstarrangements for promoting in-depth understanding. … Understanding is an interpretive[emphasis in original] process in which students must be active participants.”

Spaced vs. massed learning

Interpretive, interactive learning, where learners take inand reproduce information in multiple formats and apply it to differentcontexts and problems, can easily be accomplished using spaced learning. Andvarying the information and context aids learning in other ways.

One reason that people learn and remember more during spacedpractice might be that they pay more attention. Janet Metcalf and Judy Xu’s study(see References), which reproduced results of earlier research, explored thathypothesis. They compared massed and spaced learning to test inductive learningand to gauge the degree to which participants “mind wandered,” or let theirfocus drift from the task.

Metcalf and Xu describe a cycle of attention and learning,pointing to the psychological and behavioral concept of habituation: “It haslong been known that stimulus repetition results in habituation, with theattendant loss of attention to the repeated stimulus.” In plain English, thatmeans people stop paying attention to something that’s repeated—a sound, ascent, or a series of similar photos, for example.

The authors describe so-called “stop rules” in learningresearch that say people “stop studying when they have reached an internalcriterion indicating that the item is sufficiently learned” or they“perceive that they are no longer taking in new information.” Either or both ofthese conditions could easily occur during “cramming” or massed learning,causing learners to “mind wander.”

Their study looked at participants’ ability to determinewhich artist created a work of art. Participants looked at multiple examples ofthe work of each of several artists. In the massed learning condition, manyworks by the same artist were presented in succession; each viewing sessionpresented a different artist. In the spaced learning condition, participantsviewed a mix of works of different artists within each viewing session. Allparticipants were later asked to view images of different works from thesame artists and to figure out which artist had created them.

Participants in the spaced learning condition reported lessmind wandering than those in the massed condition. Their recall of theinformation was better than that of learners in the massed learning condition,and spaced learning led to a better ability to apply the information to a new problem—correctlyidentifying the artist who created works that they had not seen previously.

eLearning offers many opportunities for spaced learning andretrieval

The examples provided illustrate very different applicationsof spaced learning. The “spacing” can occur within a single session or byscheduling sessions several hours or days apart. Dr. Paul Kelley, a Britishneuroscientist, uses a format that separates sessions by only a few minutes, asdescribed in “Buzzword Decoder: Spaced Learning.” Spacing can apply to time, content, or both.

But whatever paradigm is used, eLearning offers a variety ofways to implement spaced learning. Spaced learning is possible using a range ofplatforms and delivery methods, including virtual classrooms, desktop or mobiledevices, and synchronous or asynchronous delivery.

References

Halpern, Diane F.,and Milton D. Hakel. “Applying the Science of Learning to the Universityand Beyond: Teaching for Long-Term Retention and Transfer.” Change:The Magazine of Higher Learning, Vol. 35, No. 4. July/August2003.
https://www.baylor.edu/atl/doc.php/250293.pdf

Hogle, Pamela. “Buzzword Decoder: Spaced Learning.” Learning Solutions Magazine. 8 November2016.
/articles/2122/?utm_campaign=lsmag&utm_medium=link&utm_source=lsmag

Metcalfe, Janet, and Judy Xu. “People Mind Wander MoreDuring Massed Than Spaced Inductive Learning.” Journal of ExperimentalPsychology: Learning, Memory, and Cognition, Vol. 42, No. 6. June 2016.