Why Errors in Memory Arise and Why They Might Be Beneficial

by Ariana Keith

Have you ever experienced a time when you’re recalling a story that you’re sure happened to you, but a loved one interrupts and says, “Actually, that happened to me, not you”? Or have you had no memory of a story your friend shared of you two from last year? Errors in memory are very common occurrences and can happen for a variety of reasons. Errors can occur in any of the three phases of the episodic memory cycle. In the encoding phase, errors arise while processing the original event. Encoding failure is when you fail to build and represent your experience in a way that can be stored in your brain. Two major failures in encoding include active (forgetting by erasing traces and forgetting by inhibiting) and passive (unsuccessful encoding). You may forget someone’s name immediately after they introduce themselves to you. Or when you reach the end of a passage of a book, you have no idea what you just read.

In the storage phase, storage failure comes about when you build the experience, but lack the structural integrity that is needed to hold on to the information over time. As time passes, our memories shift from storing the specifics of what happened to storing just the gist of the event. Only a select few memories will transition from being available moments after an event has occurred to being available days, weeks, or months later. You may have just learned 10 vocabulary terms for your Spanish course. However, when you take your exam the following day, you may not remember what any of the translations are. Other storage errors include verbal overshadowing, rehearsals that may include incorrect elements, and rehearsals that may be unconsciously influenced by our interpretation of an event.

Finally, errors in the retrieval phase are when you have stored the knowledge, but have difficulty reconstructing it at the moment when it is needed. Retrieval requires an active process of reassembling the building blocks, brain cells and connections between them, of memory. Interference is frequently the reason why we experience retrieval failures. This is when similar materials compete, making it difficult to recall specific information. You may go to the library every day to study. It is likely you remember what exact seat you sat in yesterday at the library. However, over time, it becomes more difficult to retrieve any specific memory. If you were asked to recall where you sat last Thursday, it is likely that you would not remember. Retrieval errors can also be due to stress. Stress disrupts the functioning of the hippocampus, which stores the blueprints and orchestrates the memory reassembly process, and makes it difficult to rebuild memories. Under stress, you might not be able to find the blueprints to assemble the memory or the initial blocks assembled may detach as you add more blocks. When you are stressed, your brain prioritizes figuring out what is going on in the environment now and does not focus on remembering the past. For example, you may be taking an exam and are unsure of the answers to two questions in succession. You may begin to feel stressed, and thus you may forget the rest of the information that you need to answer the remaining questions on the test. Another feature that leads to retrieval error is that we tend not to remember an event in exactly the same way twice. Each time you build a memory, its construction is slightly different.

Failures at any one of these three phases of the episodic memory cycle can lead to two major memory distortions, errors of omission and errors of commission. Errors of omission occur when there are missing pieces of information in a memory. This can be due to exhaustion, hunger, or stress. Errors of commission occur when there are missing details in one’s memory. Sensory details often fade quickly from one's memory, which leads the brain to “fill in” missing details with general knowledge that is consistent with the gist of the memory. This is called excessive pattern completion. The hippocampus is constantly conflicted between pattern completion and pattern separation. The pattern separation area of the brain, the dentate gyrus, aims to discriminate information into distinct representations so it can be remembered. The pattern completion part of the brain, CA3, finds what events have in common so it is easier to keep track of the similarities. In younger people, pattern separation often wins. However, as people age, pattern completion starts to win more often. As people get older, they are more likely to recognize similar situations they have experienced in their past and want to apply things from previous memories. While these shortcuts can be efficient, they are very prone to error.

The cellular patterns for the filled-in pieces' memories are very similar to those of the actually present pieces. This makes us unaware of all we’re missing - our errors of omission - and also makes us prone to errors of commission. This describes another common failure: failure to distinguish real from what is filled in or imagined. Not only do these errors occur due to similarity in sensory signatures between real and filled-in, but also because of faulty memory monitoring of whether something is a memory in the ventromedial prefrontal cortex.

Another common type of error of commission is failing to forget. This can create interferences, such as proactive interference – the tendency of previously learned material to hinder subsequent learning – and retroactive interference – the tendency of later learning to hinder the memory of previously learned material.

While these errors are generally associated with negative outcomes, there can be some benefits to having memory errors. One advantage is creative insights. Individuals who have more false memories tend to do better on tests of creative problem-solving and analogical reasoning. This is because false memories are a product of the ability to think broadly about how things are created, which improves problem-solving. Another benefit is making inferences. The loss of details makes it easier for people to see the similarities between prior places or events. A final advantage is the ability to predict the future. This occurs because the same processes that support the adaptive ability to think about the future can increase memory errors and biases.

Although there are some benefits to memory errors, we rely on memory for almost everything in our lives. For understanding the present, making predictions about the future, self-concept, in social environments, and changing our internal state or the internal state of others. Without it, we would not be able to function in the world. Thus, it is extremely important that we develop strong habits to aid us in remembering as best we can.

When encoding, a helpful tactic is to create tags by arousal, attention, novelty, and goal relevance. It is also beneficial to use the FOUR Principles: focus attention, organize, understand, and relate information. It is important to pay attention to the information you are trying to remember. This devotes the brain’s resources to its processing. The organization of material decreases the demands placed on the brain during encoding. For example, chunking numbers of a phone number into more familiar sets makes the entire structure easier to encode. Understanding makes sense of what you are trying to remember and gives it meaning. Relating connects the information to what you already know. This uses the building blocks that are already stuck together in your brain.

When storing, spaced rehearsal, sleep and exercise help us remember better. Active storage processes occur optimally when we are asleep. Sleep allows for the brain to go through the information of the day without needing to process the world around you. Too little sleep prevents the brain from having the neurobiological environment needed to stabilize the neural code of an event into a lasting memory. Content that is surprising or distinctive can also be prioritized for storage. One can do this by highlighting the most important information from a textbook, for example.

When retrieving, it is important to breathe and relax, as stress is extremely disruptive to memory retrieval. It can also be helpful to think back to the prior context where the memory was encoded. Picturing the location of and emotions felt during the memory will help bring the memory to mind.

Memory is extremely important, not only as a record of one's past, but to understand the present and the future. It is important to be aware of all the errors that can take place throughout the memory cycle, and how to reduce them as much as possible to live a happy and healthy life.