Remember to forget: The power of forgetting in information recall

We welcome Diploma Programme (DP) graduate Liam D’Souza of Turner Fenton Secondary School to share advice on the study techniques he used to earn a degree in STEM. This is his first story in the graduate voices series.

By Liam D’Souza

The dread of mindless memorization of lecture notes often discourages students from pursuing higher studies in the biological sciences, such as degree programs at the university level or just science elective courses meant to round out an arts degree. The fear of facing an information overload when taking concurrent year-long courses with cumulative exams is a compounding factor. As a recent biomedical engineering graduate, I’ve had the unique experience of taking memorization-heavy courses alongside ones with open-book exams, often in the same semester. I’ve learned that forgetting is a powerful but neglected tool for reinforcing retrieval strength of studied material that should be exploited alongside conventional memorization strategies.

Memory tricks, such as simple mnemonic devices and lesser variations of Sherlock Holmes’ ‘mind palace’ technique, are popular not only among students in need of retaining mass amounts of information to succeed on an exam but also among competitive memorizers. Memory tricks can be generalized to an artificial, voluntary association of ideas. The majority of idea association takes place through experience and is involuntary in nature. Voluntary association is a more involved process that is useful for retaining large amounts of new information. For example, an elementary strategy for memorizing vocabulary in a foreign language is to associate similarly sounding words across languages. Visual association is another type of voluntary association that is popular in language learning, such as the Heisig method for memorizing Japanese kanji. The ‘knuckle mnemonic’, which is commonly used for recalling the number of days in each calendar month, is an example of both a visual and spatial association, albeit for the recall of a relatively small set of information.

Association, coupled with the power of forgetting, can shift concepts from temporary, working memory to longer-term memory that is useful for retrieval on exams and beyond. In a mathematical sense, forgetting is truly a powerful process. Experimentally-obtained forgetting curves are well described by the simple power function, f(t) = at^-b, where f(t) is the proportion of information that can be recalled, t is the time elapsed since the information was last studied, and a & b are experimentally-determined positive constants. Forgetting curves depict the decline in information retention over time when there are no attempts to retain it. Hermann Ebbinghaus, who pioneered studies of memory and learning in the late-nineteenth century, is known for introducing the forgetting curve and was the first to report a mathematical equation describing the shape of forgetting. Ebbinghaus, using himself as a subject, suggested that forgetting is a gradually slowing process, with the bulk of information loss occurring soon after absorption.

Forgetting and consequently needing to re-study information ahead of an exam can be demoralizing, particularly when the (re)studying-forgetting cycle for certain information seems unending. Though unintuitive, it may be advisable to treat forgetting as a necessity, rather than a hindrance, to achieving retention. In the context of studying, forgetting merely represents a loss of information from accessible memory. Conditions that result in forgetting have been shown to create opportunities to reinforce retrieval strength. Changing the environmental context between where information is absorbed and where it is reviewed or tested can promote forgetting. The ‘context effect’ is a phenomenon whereby studied material is more retrievable in its original environmental context than elsewhere. Difficulties faced by students in recalling studied material in an exam setting may be partly attributed to the context effect. Strategizing around the context effect can enable students to unleash the power of forgetting and make recall ability increasingly independent of environmental context. Students should consider re-studying and self-testing material in different locations from where the information was formally studied. This contradicts the traditional advice given to students, which is to establish a dedicated study area such as a quiet room at home or a section of a preferred campus library. Re-studying material within a different environmental context, such as in a different room, café or even under a different tree where more of it will have been forgotten, has been shown to enhance future recall of the information. Altering environmental context when re-studying and self-testing reinforces the accumulation of information in accessible memory for longer-term retrieval.

The power of forgetting in achieving long-term retention is also fundamental to the concept of distributed studying. The ‘spacing effect’ is a direct result of forgetting curves and is based upon the observation that with a longer delay between test day and the initial study session (with no or minimal studying in between), recall of studied material on test day becomes less effective. However, the true value of the spacing effect lies in the observation that when material is re-studied prior to testing, there is a retention benefit to distributing (i.e. spacing out) study sessions. Like the context effect, the spacing effect is not often appreciated by students in need of memorizing large amounts of information for an exam. Students often revert to ‘massed practice’ or ‘cramming’ (the study of material without spacing), which may result in successful recall on an immediate test. However, cramming is followed by ‘mass forgetting’, as depicted by forgetting curves, which makes it an ineffective strategy for long-term retention. Splitting study time is an easy way to take advantage of the spacing effect. For instance, if planning to allot six hours to a particular topic ahead of an exam, there is a greater retention benefit associated with studying the topic to completion in each of three separate two-hour periods than for six hours nonstop.

In a 2008 article, a research group led by Melody Wiseheart and Harold Pashler published optimal spacing intervals between first and second study periods in proportion to the time to test day. The group’s general finding was that the optimal spacing interval between the first two study sessions increases as a proportion of the time-to-test. For a test that is one week away, the group determined that the optimal first study interval is one or two days. For a third session, the group recommended studying the day prior to the test, which would mark just under a week since the first study session. For a test that is one month away, the group recommended a first study interval of one week, with a third session again on the day prior to the test. These recommendations were made with the assumption that the same material is being reviewed in each study session. Successfully employing such a strategy as a university student would involve building multiple overlapping study sequences that all culminate with test day, with each sequence pertaining to specific course topics or chapters. Spacing out the repetitive review of course material over a designated study period is key to reinforcing retrieval strength.

Taking advantage of the power of forgetting requires repetition. Repetitive studying is inherent to the spacing effect and in overcoming the context effect. While this type of studying can be unpleasant, particularly if the material is not interesting, consider the benefits of the power of forgetting towards long-term retention. Repetitive studying also enables the revisiting of previously misinterpreted information to ensure that the correct version is what remains in accessible memory and may promote learning by enabling the linking of ideas in a ‘web of logic’. Like mnemonics, a web of logic is based upon a voluntary association of ideas. However, unlike mnemonics and other deliberate memorization tools, these associations are derived directly from the study material and are not artificial in nature. Building and accessing a web of logic can effectively remove the need to use mnemonics in exam preparation. Consider the need to memorize the fact that the state of Maryland fought as part of the Union during the U.S. Civil War. Instead of creating a mnemonic to achieve this, a student could utilize the fact that Maryland borders Washington D.C. and logically argue that it would have been crucial for Lincoln to maintain Maryland in the Union to ensure that the U.S. capital did not border enemy territory. Building a web of logic requires having a degree of general fluency in the study material so that connections can be established. Being linked in a web of logic is what distinguishes learned knowledge from purely memorized knowledge. A web of logic is useful for problem-solving, which is highly applicable to exams at the university level. Even in the biological sciences, few exams are purely based on memorization of lecture material and most have questions that also test critical thinking and logical reasoning. Answers to such questions may not directly appear in textbooks or lecture notes, and thus it is important to prioritize learning over deliberate memorization.

While building a web of knowledge is ideal, it may be impossible or require too large of a time commitment. There are certain fundamental ideas, such as the axioms of vector spaces in linear algebra and the names and functions of each of the twelve cranial nerves, that effectively need to be purely memorized. This is also the case for many other ideas in the biological sciences. Accepting that deliberate memorization is necessary and strategizing accordingly is key. Exams present certain unique challenges, as the majority of life is spent not being formally tested on studied knowledge. Perhaps the reason for which deliberately keeping large amounts of information in accessible memory is stressful and exhausting is because it is unnatural. In a report by Paul Frankland and Blake Richards of the University of Toronto, it is proposed that the goal of human memory is to optimize intelligent decision-making by holding on to important ideas and letting go of less important ones. For instance, practicing physicians do not need to maintain every detail of first-year medical school anatomy in accessible memory to make life-saving decisions in the real world. This raises the question of whether results on tests that are largely rooted in memorization are indicative of future real-world success. For the foreseeable future, however, this style of testing will persist, particularly in the biological sciences. Thus, consider unleashing the power of forgetting to promote recall on test day, namely by recognizing the context effect and the spacing effect and designing study strategies accordingly. However, prioritize learning over memorization and keep in mind that recalling everything from every course is neither necessary nor is the end goal of university.

Liam D’Souza is a graduate of the IB Diploma Programme (DP) at Turner Fenton Secondary School in Canada. He completed a B.A.Sc. in Engineering Science at the University of Toronto and is currently working in software consulting. In his free time, he enjoys playing basketball and volunteering as an editor for an undergraduate scientific journal. Connect with him on LinkedIn here.

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