Why can’t you remember what you had for lunch three days ago? What makes some memories stick while others fade away?
In her book Remember, Lisa Genova explains why we forget things and how memory failures are often a normal part of brain function. She asserts that our brains evolved to be selective, holding onto meaningful information while letting go of unnecessary details.
Keep reading to discover the fascinating science behind memory—and learn why forgetting isn’t always a bad thing.
Why We Forget Things
Forgetfulness is a common experience. Do you ever wonder why we forget things? Experiencing a memory “failure” can be both frustrating and frightening, as we sometimes perceive it as a sign that our memories are degrading. Many view it as a sign of impending Alzheimer’s disease, especially those in older age groups. However, Genova explains that our brains are highly efficient, and they evolved to remember meaningful things and forget the meaningless. Much of what we forget—such as routine daily activities or minor details—isn’t actually problematic, nor is it a sign of Alzheimer’s or dementia. Sometimes though, we forget things we care about, not because our memory is failing but because we haven’t provided our brains with the necessary inputs for memory creation and retrieval.
According to Genova, our episodic memories are fundamentally unreliable and prone to distortion. This unreliability begins at the encoding stage, as we can only remember what we notice and pay attention to in the first place, meaning our memories are inherently incomplete from the start. Distortion often happens at the consolidation stage: During this period, memories can be altered by imagination, beliefs, biases, dreams, other people’s memories, and various other influences.
Even after memories are stored, explains Genova, they remain susceptible to change. Over time, the neural networks that store a particular memory can weaken or go away entirely, which can weaken or delete that memory.
Finally, memories can also be distorted during retrieval, says Genova. Every time we retrieve a memory, we’re not playing back a recording but rather reconstructing the event. This reconstruction process often involves filling in gaps, reinterpreting details, and incorporating new information or perspectives. When we store the memory again after recall, we save this altered version, canceling out the original. This process means that frequently recalled memories, such as stories we tell often, can become increasingly distant from what actually occurred.
| Memory “Sins” and Constructive Memory Theory The unreliability of memory is well-established in psychology. Author and psychologist Daniel Schacter identified seven “sins” of memory, or specific ways in which memory can fail. The first of these seven are related to omission and include transience (our memories become weaker as we age), absent-mindedness (attentional lapses and minor forgetting), and blocking or tip-of-the-tongue syndrome. The other four memory sins are related to commission and include suggestibility (the tendency of our memories to change or distort in response to things such as leading questions or lies), bias (implicit beliefs or knowledge that can distort our memories), persistence (being unable to forget something you want to forget, such as a traumatic experience), and misattribution (thinking you’ve seen or heard something that you didn’t). And, while memory distortions and failures may seem like major flaws, constructive memory theory argues that they’re actually adaptive—they evolved for a functional purpose to aid our survival. According to this theory, one of the main functions of memory is to help us plan for future events, and because the future doesn’t perfectly repeat what’s happened before, our memories adapted to flexibly alter our memories to better simulate and predict potential future occurrences. |
Why We Need to Forget
While normal memory loss can be frustrating, it also serves an important purpose. If we remembered everything in perfect detail, our brains would become crowded with information, making reasoning and remembering difficult. Genova challenges the common perception of forgetting as a passive, default process that happens to us only involuntarily. Instead, she presents forgetting as an active, purposeful, and often beneficial process. Forgetting routine details such as what we ate for lunch yesterday or how much traffic we drove through this morning actually helps us function more effectively by clearing mental space for new, relevant information.
(Shortform note: In addition to freeing up brain space, experts note another adaptive explanation for why we forget so much: We didn’t evolve to remember the world, but rather to understand it. While memory serves a vital function in our cognitive processing, remembering isn’t the brain’s primary goal; instead, the goal is to experience the world in the moment and use it to plan future actions. So a memory that won’t enhance our understanding of the world or help us make decisions about what to do next will likely be quickly forgotten.)
