Forgetting is an inevitable part of the human experience. People forget names, dates, appointments, and even entire events. It is frustrating to have something on the tip of your tongue, only to forget it completely moments later. But why do humans forget things? There are various theories as to why forgetting occurs, including biological, environmental, and even psychological factors.
“While we may never know exactly how and why memories tend to leave us over time, one thing is for certain: You will forget about this article in the future.”
One of the most popular theories as to why people forget things is simply due to the passage of time through a process called memory decay. Memory decay refers to the gradual fading or weakening of memories over time. Memory decay was originally hypothesized by professor John Brown of the University of London in 1958, in a groundbreaking study done to quantify forgetfulness. The theory was that memory traces decay over a brief time period until a threshold is reached and the memory becomes unreachable.
According to Brown, forgetting is the direct result of decay. Essentially, memories are formed when neurons in the brain form new connections, known as synapses. These synapses create pathways for electrical impulses to travel through the brain. When the same path is traversed repeatedly, the connection becomes stronger, creating a stronger memory. However, if these pathways are not reinforced regularly, they can weaken over time, leading to memory decay. In a way, the brain’s neural connections are akin to muscle tissue that needs to be exercised in order to stay strong. If a memory is not accessed or recalled for an extended period of time, the connections associated with that memory can decay, making it more difficult to recall the information or aspects of the memory later. While this theory does have numerous supportive studies, it is not the only theory proposed to explain forgetting.
Another theory as to why humans forget things is due to interference. Interference occurs when new information is learned that interferes with the retrieval of previously learned information. For example, if one is trying to recall the name of a person they met last week, but then meets someone new with a similar name, it may become difficult to retrieve the correct name. This type of forgetting is known as retroactive interference. Proactive interference is the opposite of retroactive interference, where old memories interfere with the retrieval of new memories.
For instance, if someone has learned a certain skill, it can be challenging to learn a new one that contradicts the old one, even though it may be more efficient or effective. Due to the prominent correlation between interference and forgetting, a 2019 study from New York University used a variety of behavioral and neuroimaging studies and four separate experiments in order to find ways to reduce the effect of interference on memory. This study did ultimately identify ways to prevent interference from causing forgetting, such as limiting distractions in one’s life and workspace. However, the study acknowledged that solely limiting interference does not account for other factors that can cause forgetting such as stress and age.
“If a memory is not accessed or recalled for an extended period of time, the connections associated with that memory can decay, making it more difficult to recall the information or aspects of the memory later.”
When people are under stress, their brain releases cortisol, a hormone that can interfere with memory consolidation, making it more difficult to form new memories. In fact, there is developing research that indicates high cortisol levels are associated with memory loss and cognitive dysfunction. This may even correlate to the development of Alzheimer’s disease, a neurodegenerative disease impacting memory. Furthermore, aging is a factor that can contribute to forgetting. As people age, their brain undergoes changes that can make it harder to form and retrieve memories. For example, the hippocampus, a brain region critical for semantic memory, which stores statistical and objective information, can shrink with age, and the connections between neurons can weaken.
Overall, forgetting is a natural and inevitable part of the human experience. People forget things for various reasons, including the passage of time, interference, stress, and aging. While it can be frustrating to forget important information, it is important to remember that forgetting is a natural and normal part of the brain’s functioning. While we may never know exactly how and why memories tend to leave us over time, one thing is for certain: You will forget about this article in the future.
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