In what ways can forgetting be useful and adaptive?

Hyperthymesia is a rare condition characterized by a profoundly strong, and often burdening, ability to recall memories in vivid photo- and video-graphic detail—a type of autobiographical memory. These types of ingrained memories are often those of personal experience, as opposed to rote memorization of facts pertaining to different subjects. Despite the seemingly beneficial effects of having such versatile and clear memory, there are potential psychosocial impacts that can mentally strain an individual constantly burdened by an overwhelming influx of detailed memories—the mental processing of all these events gives rise to mental distress, coupled with the unwanted recall and replaying of traumatic events in vivid detail. These vivid memories are inescapable, in a sense, to those affected by hyperthymesia.

The apparent affliction caused by hyperthymesia lends credence to the utility of forgetting in our daily lives, which can prove to be both functional and adaptive for a variety of purposes—particularly in the filtering and acquisition of relevant and irrelevant, unwanted information. Moreover, forgetting plays a role in preventing existing memories from interfering with the retrieval of memories (interference theory), as well as the formation of new memories and associations. Along with knowledge acquisition, general sentiment in literature suggests that forgetting traumatic memories is an adaptive method for emotional regulation, allowing individuals to cope with trauma and retain mental well-being by filtering out negative memories (Norby, 2015).

The overwhelming literature on forgetting argues that forgetting is essential for adaptive learning and emotional regulation, ultimately overall cognition of one’s life—while generalizing the utility of forgetting varies between individual circumstances and environments, many researchers that argue forgetting as a helpful mechanism for learning focus on the emotional impacts of forgetting in context of traumatic personal experiences. They also pose theoretical frameworks surrounding cognitive and memory processing that explain how forgetting increases the quality representation of relevant and important stimuli (Davis & Zhong, 2017). These frameworks, however, seemingly neglect the essential role that general information retention plays in semantic memory—in our daily lives, whether in social, academic, or occupational settings, where harmless forgetting can have potentially negative consequences. While different forms of forgetting in daily life complement each other in maintaining mental and emotional stability—particularly in cases of traumatic, negative personal experiences, and episodic memory—and allow for efficient and optimized cognitive processing of events and experiences, forgetting should not necessarily be fully endorsed as an adaptive or useful human “function” based on these theoretical models of memory processing: emphasis should also be placed on the trade offs and respective costs that this loss of information can have for individuals, particularly in semantic memory.

Forgetting, thus, is useful for emotional regulation and can be viewed as adaptive for efficient processing of episodic memory, but when considered in the context of semantic memory, does not necessarily reap the practical benefits that these theories would seem to suggest. In line with many of these theoretical frameworks for memory modeling, these theories generally posit that specific neurons are tuned for “active forgetting” in the brain, allowing us to filter out no longer relevant information (Ryan & Frankland, 2022)—most of these studies account for memory of personal experiences (episodic memory), as opposed to practical information one might use in different types of settings. Memory, beyond personal experiences, however, should also be taken into account when considering the usefulness of forgetting, particularly in the recollection of semantic memory and details essential for daily life. This more efficient, and emotionally beneficial, processing of episodic memory seemingly comes at the cost of forgetting presumably irrelevant details and representations in daily life. Memory loss is often categorized into passive and active forgetting. Passive forgetting occurs naturally as a result of three factors: (1) loss of context cues over time associated with memories, (2) interference of past, similar memory traces, and (3) context changes in an individual’s environment, relative to the memory, which inhibits retrieval of the desired information (Davis & Zhong, 2017). Active forgetting refers most often to “motivated” or “intentional” forgetting, where an individual with full cognitive control suppresses an unwanted memory during its encoding or consolidation upon recall, preventing the memory engram from fully forming and being retained in the mind (David & Zhong, 2017).

Forgetting often occurs as a result of competing traces interfering with the memory retrieval process, causing “inhibitory control mechanisms” to suppress certain memories in favor of retrieving the desired object (Davis & Zhong, 2017). Philosopher William James noted that: “If we remembered everything, we should on most occasions be as ill off as if we remembered nothing. It would take as long for us to recall a space of time as it took the original time to elapse, and we should never get ahead with our thinking.” Accordingly, interference theory posits that forgetting is an essential mechanism for optimizing retrieval of desired memories and details, since our brains are overwhelmed with redundant and copious information pertaining to memories. In the context of learning, forgetting has been argued to allow for the intake of new and useful information that competes with no longer relevant information encoded in our brains. As we grow and evolve over the years within different environments, old information we had encoded might not be useful in different contexts, which is why forgetting in accordance with the interference theory seems to play an adaptive role in allowing new and more relevant contextual memories to be encoded and consolidated in our brains.

Moreover, researchers in Nature argue that remembering only the gist of events, as opposed to every singular detail, allows one to generalize the event to future incidents—if one were to retain every single detail of an experience, processing that information and generalizing the experience is harder (Gravitz, 2019). On the one hand, this “controlled forgetting” allows an individual to retain important information about an event (Gravitz, 2019). On the other hand, “controlled forgetting” often occurs at the expense of information that may or may not be useful in the future (Gravitz, 2019). The utility of information in the future is not always ascertainable when we first attempt to perceive external stimuli—in the type of “controlled forgetting” that the authors argue in favor of, we make a potentially faulty assumption in discarding information we believe to be irrelevant at the time, and thus do no properly encode and consolidate these potentially useful details. This generally occurs since our brain capacities can accommodate only a limited amount of items in short and long-term memory; as a result, it can be argued that we adaptively forget certain details to retain what we believe to be relevant information. When information perceived as irrelevant is forgotten, the subjective assumptions of relevant information in memory can be flawed to start with, and result in the loss of useful information contained in memories. Some of these details may be memories that are not necessarily worth discarding from retrieval. However, subjective perception of what may be relevant and useful information is prone to error—thus, to argue that forgetting is adaptive in this sense seems flawed, as there are many cases in which we can make faulty assumptions on the importance of certain information. As such, by using potentially faulty assumptions to “control” our forgetting of certain details, we lose useful information, which comes at a cost to us.

Some researchers argue that information stored in the brain can be retrieved if forgotten, or “reversed,” with the “right intervention” and administration of contextual cues (Ryan & Frankland, 2022)—however, this process is likely arduous and unlikely if the memory had not been consolidated in the first place and then ultimately forgotten. Moreover, the time it might take for a “natural intervention” or contextual cue to trigger the memory is uncertain. This would often require manual, or special psychiatric or medical intervention, in serious cases, to revive a lost memory. Unless deliberately triggered by an individual themself or a third party, then this information is hard to retrieve under natural circumstances. The reversibility of forgotten memories, thus, is not necessarily guaranteed without the proper resources. If theories in favor of memory loss rest on the premise of the reversibility of forgotten memories, then they are potentially flawed, as forgotten memories are arguably hard to retrieve, without the proper resources.

If forgetting is active, or intentional on our part, where the individual has cognitive control in suppressing certain memories, then the impacts are likely to be more useful than in cases of passive forgetting, where we unintentionally forget certain information. Motivated forgetting in literature often refers to episodic memories that individuals wish to suppress due to its undesirable emotional impacts on the individual—as a method for coping with trauma and maintaining mental and emotional stability, individuals can selectively forget negative memories. By repetitively suppressing these memories and seldom retrieving this information, individuals can potentially induce a form of passive forgetting, where the memory naturally decays, or the individual simply does not access and relive the episodic memory. As an adaptive mechanism, this form of purposeful forgetting fosters mental and emotional health. Passive or active forgetting of traumatic episodic memories can thus prove to be useful.

However, in most cases, memory can be reasonably assumed to be passively forgotten, as opposed to actively—semantic memory, particularly, is more prone to being passively forgotten, as the retrieval of certain facts and semantic information can change more significantly in context and require substantial space and processing for storage. Semantic information is often harder to consolidate in the brain as well. While forgetting certain information can allow one to take in and learn new information, loss of semantic memory in particular can be harmful in an academic or occupational context.

Evaluating the costs of forgetting semantic and episodic memory is challenging in the light of variable circumstances between individuals—thus, generalizing the utility of forgetting is equally difficult, as they ought to be weighed differently for different types of memories. Generally, forgetting is useful and adaptive for episodic memory—for maintaining mental and emotional well-being—when it is passively or actively activated, but in the case of passive forgetting of semantic memory, vast amounts of information is lost, and the cost of this loss evidently depends on an individual’s environment and context. If the lost information is perceived as irrelevant, then this loss of memory facilitates new information being taken in, but the assumptions that our minds can make for the relevance and importance of semantic information can be flawed, leading to the loss of potentially useful information. As such, forgetting is not necessarily always useful or adaptive, even though researchers have argued that it allows for a form of learning and optimized cognition.

Works Cited:

Davis, R. L., & Zhong, Y. (2017). The Biology of Forgetting-A Perspective. Neuron, 95(3), 490–503. https://doi.org/10.1016/j.neuron.2017.05.039

Gravitz, L. (2019, July 24). The forgotten part of memory. Nature News. Retrieved November 9, 2022, from https://www.nature.com/articles/d41586-019-02211-5

Nørby, S. (2015). Why Forget? On the Adaptive Value of Memory Loss. Perspectives on Psychological Science, 10(5), 551–578.

Ryan, T.J., Frankland, P.W. Forgetting as a form of adaptive engram cell plasticity. Nat Rev Neurosci 23, 173–186 (2022). https://doi.org/10.1038/s41583-021-00548-3