Why are Memories Forgotten?

Do you remember what you ate for dinner two months ago? Or do you remember the last text message you sent to that friend you last talked to? For most of you, no, you don’t know, our minds are just simply not made to remember insignificant details, but some people can remember, but most forget. So why do we forget things, and how are they stored?

Firstly, how are memories made in the first place? As much as we talk about the brain being this muscle being capable of being highly intelligent with an inner monologue and mental thinking capacity; most of our brain is made up of neurons. 

According to the Brain Institute of Queensland, neurons are fundamental units of the brain and nervous system, responsible for the sensory input from the external world, relaying motor and thinking skills, transforming and relaying electrical signals for every step. When we experience something, the neurons in our brain physically interact with our senses, and create something called synapses, which are stored in the brain through neurons transmitting signals.

 This means that when mentally thinking and talking, we are actually physically thinking about it through the use of these neurons. When we experience something, neurons actively send electrical signals to one another to process this and store it in our hippocampus, the area of our brain that stores these electrical signals, called engrams, which are physical traces of memories that is in our brain from chemical or physical changes from external stimuli to be later recalled as what we call memories. This is how memories are created and stored. 

But how are they forgotten? Do these electrical signals for memories just shut off after a while, or are there specific reasons for why the brain forgets things? While we are not entirely sure, it is mostly due to passive decay from ageing. As our body naturally ages, our mind becomes weaker and fewer electrical connections can be made therefore weakening our memory, or the possibility that retrieving these memories may take more time for us to be aware of it. The BBC Science Magazine also states that memories could be forgotten as we did not actively remember it the first time. 

There are actually four proven reasons why we forget; they are: passive decay as mentioned above, forgetting caused by failure to store, forgetting caused by interference, and motivated forgetting. Passive decay has already been mentioned, but what about motivated forgetting and the others. Motivated thinking is where our brain intentionally forgets memories, especially those of traumatic and disturbing events or experiences. These memories are negative and harmful to us, so we may want to eradicate them and provoke anxiety. We can passively suppress these memories and repress them; the unconscious form of forgetting. Failure to store is quite interesting, as our brain can omit certain details when some are more important. For example, a classic study is to ask US citizens to identify the correct penny from the other, except the size and colour are the same, the key details of identifying a penny, most participants fail as they do not remember the smaller details of this super common object.

Forgetting may also be intentional and speed up the brain, one study claims that forgetting is essential to free up space for critical thinking, much like a computer which stores files and slowly slows down from lack of “memory” and can make decisions faster from remembering fewer things. Neuroscientist Maria Wimber says that forgetting is good and an adaptive thing. She says that recent research has discovered that forgetfulness is not necessarily a sign of a faulty memory, but rather the goal of the brain is not to remember. The brain is not made to preserve information but to make faster decisions based on past experiences. 

Ultimately, forgetting is quite unknown but many prevailing theories have a very high chance of being true, with passive decay being 100% true. . Memories are formed by neurons making electrical connections via synapses, which are later turned into engrams and stored in the hippocampus where it can be retrieved. Our brain naturally slows down over time and forgets some things in the process.  Forgetting may also be tied to failure to store an engram, and motivated forgetting is used to forget bad memories like depression and PTSD. In summary, memory may not always be a bad thing, despite how much we all want photographic memory, so embrace the present, as that may be remembered one day.

Budson, A., & Kensinger, E. (2023). Why we forget and how to remember better: The science behind memory. Harvard University Press.
Cherry, K. (2023, March 15). 4 key reasons for forgetting. Verywell Mind. https://www.verywellmind.com/forgetting-and-the-forgetting-curve-2795346
How are memories formed? (n.d.). Queensland Brain Institute - University of Queensland. https://qbi.uq.edu.au/brain/learning-memory/how-memories-formed
National Institute on Aging. (n.d.). Memory, forgetfulness, and aging: What’s normal and what’s not? National Institute on Aging. https://www.nia.nih.gov/health/memory-forgetfulness-and-aging-whats-normal-and-whats-not
National Institutes of Health. (2010, February). Things forgotten: Simple lapse or serious problem? NIH News in Health. https://newsinhealth.nih.gov/2010/02/things-forgotten
Siegfried, T. (2019, February 18). Why do we forget things? it may make the mind more efficient. Discover Magazine. https://www.discovermagazine.com/mind/why-do-we-forget-things-it-may-make-the-mind-more-efficient
What is a neuron? (n.d.). Queensland Brain Institute - University of Queensland. https://qbi.uq.edu.au/brain/brain-anatomy/what-neuron