By Mady Cheng
Our memories define who we are. This is the psychological process that enables us to store, retain, and retrieve information. It fosters our capacity to learn, adapt, and navigate the complexities of life. However, this process is not often perfectly executed. As humans, we have all experienced times when we forget things, like people’s birthdays, or where you put your phone down thirty seconds ago. In this article, short-term memory will be discussed, including where memories are stored, how long they are stored for, the difference between short-term memory and long-term memory, and last but not least, memory techniques using location.
Introduction to memory
For a memory to be formed, our brain encodes and stores information within the intricate network of the brain, waiting for subsequent retrieval. Most of the time we are not aware of these retrieval networks until we need to remember them again. This memory retrieval process allows us to transfer the stored memory back into conscious awareness.
Episodic memories are stored in the hippocampus, located in the brain’s temporal lobe, they are stored there until further retrieval. Episodic memory refers to the ability to recall autobiographical memories of events that took place in a specific location and timeframe. So how did scientists figure this out? Thanks to the edifying case of Henry Molaison, who
lost his memory in 1953 due to a risky psychosurgical procedure designed to cure his epilepsy. The procedure involved removing the front half of the hippocampus on both sides and most of the amygdala. Unfortunately, the operation went awry, resulting in Henry losing the ability to store or retrieve new experiences. Molaison’s memory loss was extremely specific. He forgot his experiences after the operation within 30 seconds but retained his pre-27 years of life. This case brought a significant discovery to the study of memory as it was previously believed that it was the property of the whole brain, and Molaison’s brain revealed parts of memory could be localised to specific brain areas.
How memories are stored
There are three stages for short-term memories in our brain, encoding, storage and retrieval.
Encoding is the initial phase of learning, it is the stage where memory is perceived and learned. This is a selective and prolific process, allowing us to attend some events in our environment and ignore unnecessary ones, distinctiveness is extremely crucial in terms of remembering events and enhancement can be done by adding emotional content. Recoding is a part of encoding, it is the process which allows us to convert information into a form that we understand.
Our memory traces are not perfect, instead, they are subjected to reconstruction and are influenced by our own experiences. Also, memories can consolidate during the time between learning and testing which aids retention. This is affected hugely by interference. Retroactive interference, which refers to the new activities you did in between old memories and when you're trying to retrieve them, is the main cause of forgetting (McGeoch, 1932). To give an example, do you remember what you had for lunch yesterday? You might answer yes, but if I asked you what you ate for lunch two weeks ago, would you still remember? On very rare occasions, you might do, but most likely you would not remember (assuming you eat a different lunch every day). This is caused by the retroactive interference created by the lunches you ate in between the two weeks. New things can interfere with our memory process, but so can the opposite happen. Proactive interference refers to memories interfering with new ones. For example, when you study a second language, your native language will impair your fluency in the foreign language, as vocabulary or grammar from your first language will appear in your head subconsciously, making it hard to have your second language as fluent as your native language.
A major problem with interference, especially retroactive interference, is stated by Cara Laney and Elizabeth Loftus in the module “Eyewitness Testimony and Memory Biases”. In the module, they acknowledged the importance of eyewitness testimony to the jurors but questioned the reliability as Mistaken identifications can result in false accusations and wrongful convictions. Because of retroactive interference, the reliability of eyewitness memory can be compromised by suggestive questioning, misinterpretations of events, interactions with co-witnesses, and personal preconceptions about how events unfolded. In some cases, witnesses might even form recollections of events that entirely never occurred.
Endel Tuving (1991, p.91) argued that “the key process in memory is retrieval”. Retrieval is the process of getting information out of our brain storage. This is the time when we can tell if the memory stored is indeed short-term memory or long-term memory.
Short-term memory vs Long-term memory
Short-term memory is stored and retrieved sequentially, for example, when you are given a list of ten words and are asked to remember them, when you are told to name the sixth word, you will probably go through the list to retrieve the word. Short-term memory is a component of memory that has a limited amount of information in an active and easily accessible state for a brief duration, usually spanning 15-30 seconds. Per Atkinson and Shiffrin's model (1971), items can be retained in short-term memory by vocally repeating them, which involves acoustic encoding and is referred to as the process of rehearsal. Peterson and Peterson (1959) demonstrated that as the delay between encoding and recall increases, the amount of information that can be remembered decreases. They used the Brown-Peterson technique, which involves the presentation of a trigram, followed by instructions to count backwards from a specified number by intervals of three or four. This method assessed short-term recall abilities without relying on the use of rehearsal to maintain the information in memory. The finding proves the rapid loss of information from memory when rehearsal is prevented indicates short-term memory does have a limited duration.
Other than the duration, our capacity for short-term memory is also very limited. Proposed by George Miller (1956), the average number of objects a human can hold in the brain is about 7, (plus or minus 2). The “magic number 7” theory is supported by numerous studies, for example, Jacobs (1887) employed the digit span test with every letter in the alphabet and numbers, but excluding "w" and "7" due to their two-syllable nature. His findings revealed that people recall numbers better than letters, with numbers having an average span of 9.3, while letters have 7.3. Nonetheless, we need to acknowledge that the complexity of items and individual differences can influence our capacity. These experiments and theories also suggested that it is possible to enhance our capacity by grouping information into chunks, so they are more manageable as a bigger unit.
On the other hand, Long-term memory is stored and retrieved by association. The two types of LTM are explicit and implicit memory.
Explicit memory is a type of long-term memory that you need to consciously make an effort to remember. These memories are used in everyday life, ranging from recalling a date and time for a meeting to general knowledge that you learned in school or on social media. Semantic memory is a type of explicit memory for understanding conceptual facts about the world. An example of this is remembering your relatives and friends' names or even their birthdays. Episodic memory is another type of explicit memory, which is the capacity for recollecting autobiographical memory of events according to specific events in a certain space and time, like remembering your sixteenth birthday every time you see a teenager celebrating their sweet sixteen. Both of these types of explicit memories require encoding and retrieving from deliberated rehearsal. They are often drawn into awareness through associations.
In terms of implicit memory, there is procedural memory, which is a type of memory that enables us to carry out commonly learned tasks without any conscious thoughts. For example, when you repeatedly hear a song many times, you will be able to sing it without trying very hard to remember the lyrics or melodies. Another type is emotional memory, which covers the ability to vividly recall events or experiences that were accompanied by strong emotional reactions. Unfortunately, we seem to have greater intensity on events we would like to forget than pleasant ones, for instance, we might be able to distinctly remember the anguish and grief of when we lost someone close even though it might be a decade ago. Implicit memory becomes automatic over time with repetition, they can be reserved for priming, or reacting similarly to a stimulus. It can also be extremely useful for beginning and mastering a skill.
Memory techniques using location
We know how episodic memory works and they offer a means to access semantic information by their episodic characteristics. Episodic memory records the connections between typical pieces of semantic knowledge and the specific events when they were initially acquired, and this allows us to take advantage of them to remember pieces of knowledge, especially for revision. Two techniques I find useful are the Body System and the Memory Palace.
For a short list of terms actions or events, we can use the Body System. Let’s say we have to remember the different types of forces, first, we make eight stops from head to toe, and simply connect each context with a body part. For example, we can connect the head with electrostatic force, imagine your head lights up when you get an idea. Another example is we can connect the nose with nuclear force, smelling the burning scent, or imagine your neck with a scarf for thermal energy, of course, the easy one would be the leg with kinetic energy when running. Since you will know the order of your body parts, you will always know part of the image that comes next, and your brain will fill in the missing part so it’ll be easy to finish listing your eight energy forces. You can add more stops in your body according to the length of your list. My suggestion for ten is: head, eyes, nose, mouth, neck, chest, stomach, thigh, calf, and feet. You can use this for any subject and the advantage is you will always follow a specific order, which is most useful for subjects like history or geography which requires knowledge of things in chronological order.
Our body parts aren’t unlimited, so for large amounts of information, the thousand-year-old method, Memory Palace, might help store them. To start with, think of a place that you know well, like your childhood home, or if you are doing an exam in your school hall, thinking of that might help too. Create a route with stops, like at the kitchen and your backyard, and then store your pieces of knowledge the same way you did in the Body System, correlating places with the information you need to remember. By frequently embarking on these memory journeys, you can effectively preserve the information stored for a long duration. This strategy is commonly employed by world-class memory champions who can construct memory journeys encompassing thousands of waypoints.
Conclusion
In conclusion, memory plays a vital role in defining our identities and facilitating our capacity to learn, adapt, and navigate life's complexities. While memory can occasionally fail us, understanding its mechanisms is essential. Knowing the difference between short-term memory and long-term memory allows us to take advantage and use techniques like the Body System and Memory Palace to enhance memory and recall, especially for educational purposes. Ultimately, memory is a fascinating and intricate aspect of human cognition that continues to be explored and harnessed by experts and individuals.
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