Why forget

The environment is changing constantly and, to survive, animals must adapt to new situations. Allowing fresh information to overwrite the old helps them to achieve that. Researchers think that the human brain might operate in a similar way.

Studies of people with exceptional autobiographical memories or with impaired ones seem to bear this out. People with a condition known as highly superior autobiographical memory HSAM remember their lives in such incredible detail that they can describe the outfit that they were wearing on any particular day.

Those with severely deficient autobiographical memory SDAM , however, are unable to vividly recall specific events in their lives. As a result, they also have trouble imagining what might happen in the future.

The integration of new neurons green into the hippocampus red bands degrades stored memories. Credit: Jagroop Dhaliwal. Various symptoms of these conditions — including flashbacks, obsessive thoughts, depressive rumination and difficulty controlling thoughts — have been linked to an overactive hippocampus. A better understanding of how to help people make traumatic memories less intrusive could help researchers to treat some of the most intractable cases.

When Anderson and his colleagues looked at what happens when volunteers suppress unwanted memories — a process he calls motivated forgetting — they found that people who reported more traumatic experiences were particularly good at repressing specific memories 5.

Understanding the cognitive psychology that underlies that ability, as well as the mental resilience that is necessary for developing it, could help to improve treatment for PTSD. If forgetting is truly a well-regulated, innate part of the memory process, he says, it makes sense that dysregulation of that process could have negative effects.

More from Nature Outlooks. That question is yet to be answered. But more memory researchers are shifting their focus to examine how the brain forgets, as well as how it remembers.

In the past decade, researchers have begun to view forgetting as an important part of a whole. Memory, first and foremost, is there to serve an adaptive purpose. It endows us with knowledge about the world, and then updates that knowledge. This article is part of Nature Outlook: The brain , an editorially independent supplement produced with the financial support of third parties.

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Sign me up. While the information is somewhere in your long-term memory, you are not able to actually retrieve and remember it.

Psychologist Hermann Ebbinghaus was one of the first to scientifically study forgetting. In experiments where he used himself as the subject, Ebbinghaus tested his memory using three-letter nonsense syllables. He relied on such nonsense words because using previously known words would have involved drawing on his existing knowledge and associations in his memory.

In order to test for new information, Ebbinghaus tested his memory for periods of time ranging from 20 minutes to 31 days. His results, plotted in what is known as the Ebbinghaus forgetting curve, revealed a relationship between forgetting and time. Initially, information is often lost very quickly after it is learned. Factors such as how the information was learned and how frequently it was rehearsed play a role in how quickly these memories are lost.

Information stored in long-term memory is surprisingly stable. The forgetting curve also showed that forgetting does not continue to decline until all of the information is lost. Sometimes it might seem that information has been forgotten, but even a subtle cue can help trigger the memory. Imagine the last time you took an exam for school.

While you might have initially felt forgetful and unprepared, seeing the information presented on the test probably helped cue the retrieval of information you might not have known you even remembered. So how do we know when something has been forgotten? Of course, many factors can contribute to forgetting. Sometimes you might be distracted when you learn new information, which might mean that you never truly retain the information long enough to remember it later.

Well-known memory researcher Elizabeth Loftus has proposed four key explanations for why forgetting occurs. These have led to some major theories of forgetting. What did you have for dinner Tuesday night of last week? Is that difficult to recall? If someone had asked you that question Wednesday morning, you probably would have had no problem recalling what you had for dinner the night before. But as intervening days pass, the memories of all the other meals you have eaten since then start to interfere with your memory of that one particular meal.

This is a good example of what psychologists call the interference theory of forgetting. According to interference theory, forgetting is the result of different memories interfering with one another. The more similar two or more events are to one another, the more likely interference will occur. It is difficult to remember what happened on an average school day two months ago because so many other days have occurred since then. Unique and distinctive events, however, are less likely to suffer from interference.

Your high school graduation, wedding, and the birth of your first child are much more likely to be recalled because they are singular events—days like no other.

Interference also plays a role in what is known as the serial position effect , or the tendency to recall the first and last items of a list. In all likelihood, you will probably be able to easily recall the first and last items on your list, but you might forget many of the items that were in the middle. The first thing you wrote down and the last thing you wrote down stand out as being more distinct, while the fourth item and seventh item might seem so similar that they interfere with each other.

Eliminating interference altogether is impossible, but there are a few things you can do to minimize its effects. One of the best things you can do is rehearse new information in order to better commit it to memory. In fact, many experts recommend overlearning important information, which involves rehearsing the material over and over again until it can be reproduced perfectly with no errors. Another tactic to fight interference is to switch up your routine and avoid studying similar material back to back.

For example, don't try to study vocabulary terms for your Spanish language class right after studying terms for your German class. Break up the material and switch to a completely different subject each study session. Sleep also plays an essential role in memory formation.

Select personalised ads. Apply market research to generate audience insights. Measure content performance. Develop and improve products. List of Partners vendors. While you might find yourself wondering why is my memory so bad , forgetting is part of life and people forget surprisingly fast.

The reality is that while the brain is capable of impressive feats, its capacity to store and recall details is limited. There are a few different ways and reasons that we forget things.

Forgetting is the loss or change in information that was was previously stored in short-term or long-term memory. It can occur suddenly or it can occur gradually as old memories are lost.

While it is usually normal, excessive or unusual forgetting might be a sign of a more serious problem. Have you ever felt like a piece of information has just vanished from your memory? Or maybe you know that it's there, but you just can't seem to find it.

The inability to retrieve a memory is one of the most common causes of forgetting. So why are we often unable to retrieve information from memory? One possible explanation of retrieval failure is known as decay theory.

According to this theory, a memory trace is created every time a new theory is formed. Decay theory suggests that over time, these memory traces begin to fade and disappear. One problem with this theory, however, is that research has demonstrated that even memories which have not been rehearsed or remembered are remarkably stable in long-term memory.

Research also suggests that the brain actively prunes memories that become unused, a process that is known as active forgetting. As memories accumulate, those that are not retrieved eventually become lost. Sometimes people forget due to a phenomenon known as interference. Some memories compete and interfere with other memories. When information is very similar to other information that was previously stored in memory, interference is more likely to occur. There are two basic types of interference:.

Sometimes the act of remembering something can lead to other things being forgotten. Research suggests that retrieving some information from memory can lead to retrieval-induced forgetting. This is particularly common when memory retrieval cues are very similar. While this causes forgetting, research also suggests that this type of forgetting can actually be adaptive.

By forgetting one memory in favor of another, it reduces the chance of interference happening again in the future. While interference can make it difficult to remember some things, there are things you can do to minimize its effects. Rehearsing new information is often the most effective approach.