Knowledge Representation and Memory

Understanding what it takes to remember and recall what we need to survive and thrive

Phonological Loop

Groundhog Day

In the 1993 film Groundhog Day, Bill Murray’s character, weatherman Phil Connor, ends up repeating the same day over and over again. And yet, as the only person aware of the loop he is stuck in, he uses his memory of events from his ‘future’ to his advantage.

After all, **our memories shape how we respond to our environment**, because knowing the past helps us predict what is to come. Many of our earlier experiences are sufficiently similar to future ones that our memories provide a distinct advantage. Early research found that the speed at which we can retrieve an item from memory is influenced by how frequently we encountered it in the past.

Somehow **the mind appears to be predicting which items will be valuable in the future based on their prior usefulness**. It’s like a helpful and experienced college librarian who second-guesses the needs of a new batch of students with the right book in hand when they arrive at the desk.

Multi-store models of memory

The auditory store, or **‘echoic’ memory**, lasts only a few seconds yet allows you to playback what has been said even when you weren’t listening closely to what was said.

Testing has shown short-term memory is also limited – recalling approximately 7 items without error. Yet, we typically chunk items for ease, such as with the letters P, S, Y, C, H, O, L, O, G, and Y; we can form 1 chunk rather than 10 items.

Our long-term memory is seemingly limitless. And yet, it has been suggested that, if each synapse of our brain were similar to a single bit of information, we would be able to store approximately **12,000 gigabytes of data** – enough to hold the book Moby Dick 10 million times or 2.5 million songs. That’s better even than any Kindle.

Unitary-store models of memory

Recent memory models propose a **single ‘unitary’ store of memory**. According to this approach, **short-term memory is not distinct but rather the temporary activation of long-term memory**.

And yet, a challenge for such a model comes from amnesia patients – often presenting with issues with short-term memory. Yet, according to supporters of the unitary approach, it is not the result of damage to different memory stores but the ability to form novel relations between items and their context.

**Researchers have identified that amnesic patients often have damage to the hippocampus**. They perform exceptionally poorly on tests involving a very short retention interval, suggesting the importance of the hippocampus in relational short-term memory.

However, **some challenge the notion of a unitary model as an oversimplification**. Indeed neuroimaging studies have found little support for the theory, despite identifying shared brain areas involved in both short and long-term memory.

Working memory

Related to the concept fo **’Short-term memory’**, is the more complex concept of one’s **‘working memory.’**

While short-term memory refers to the passive temporary storage system in the brain, ‘working memory’ describes an active system that allows for the temporary storage, processing, and manipulation of information, enabling complex cognitive tasks like reasoning, problem-solving, and language comprehension.

Recent versions of the working memory model suggest 4 components. The **‘central executive’** is perhaps the most important. While it does not store information, it is involved in almost all complex cognitive activities, managing attention and focus and interfacing with long-term memory.

The **‘phonological loop’** is dedicated to working memory and temporarily holds verbal information; it is vital for speech perception and production, particularly rehearsal. Similarly, the **‘visuo-spatial sketchpad’** provides temporary storage for manipulating visual patterns and managing spatial movement.

Lastly, the **‘episodic’** buffer combines visual, auditory, and other information sources, linking working memory to perception and long-term memory.

Unlike the idea of short-term memory, the working memory concept provides a valuable model for combining active processing and the temporary information storage found in all complex cognitive tasks.

Processing in long-term memory

‘What’ is stored in long-term memory may be down to its depth of analysis. The more meaning is processed, the deeper the level of analysis. Indeed, according to the ‘levels-of-processing’ approach, **how a concept of idea is processed during learning affects memorability**, producing more elaborate, longer-lasting traces.

Studies have repeatedly confirmed the superiority of deep over shallow processing on ‘explicit’ memory recognition tests where subjects are tested on their ability to recall information. It seems that **deep processing involves more conceptual processing and shallow processing more perceptual processing**.

**Research also recognizes the importance of learners having relevant knowledge**. For example, an athlete is more able to learn race times and details than a non-athlete. This is possibly the result of an increased ability to organize to-be-remembered information and a boost to distinctiveness, which also helps individuals reject familiar but false items.

Learning and memory

Learning is not only found in our attempts to study but also during information retrieval. Indeed, the **‘testing effect’** as it’s known, is surprisingly strong and can form a part of revision techniques, including re-testing, drawing pictorial representations, such as mind maps, and creating summaries. Here at Kinnu, the testing effect shapes much of how you will learn.

And **the gains to be made through retrieval practice are far greater than most people realize**. Such activities appear to increase the ability to create and retrieve mediators linking cues with what we must remember.

Also, **some learning is ‘implicit’ – involving education without awareness or even the intention to learn**. And while, experientially, it can sometimes be hard to tell the difference, **neuroimaging shows that conscious awareness during explicit learning activates different brain areas to unconscious or implicit learning**.

Furthermore, while amnesic patients experiencing damage to their medial temporal lobes may perform poorly on explicit memory tests, they can still perform as well as healthy individuals on implicit tests.

Forgetting to help remember

We all forget. Even memories once important to us can become vague – their detail lost to time. But why do we forget?

Some explanations suggest that our brain matter experiences decay or that mental processes perform a cleanup of trivial memories during sleep.

According to **‘interference theory,’ our present learning can be ‘proactively’ interfered with by prior learning and ‘retroactively’ by what is to come.** Eyewitness testimony has been shown to be notoriously inaccurate due to experiences before and after the incident.

Traumatic or threatening memories, especially those experienced during childhood, may be repressed. While difficult to access, ‘repression’ was an essential part of early psychotherapy.

However, research has found that recovered memories outside group therapy tended to be more accurate than those within treatment, suggesting not all recall is equal.

And yet, frequently forgetting may result from a lack of appropriate cues. When we store information about an event, we most likely capture the context; retrieval may not occur without proper stimuli.

Declarative and non-declarative memory

One of the most important distinctions in **long-term memory** is between **declarative and non-declarative memory**. The former relates to facts and events – they can be declared and are explicit. We literally know that something is the case, such as “Washington DC is the capital of the US,” and “Bonjour, is French for hello.”

**Declarative memory breaks down into ‘episodic’ and ‘semantic memory.’** **Episodic memory is of particular events that happened to us**, allowing us to mental ‘time travel’ to re-experience our past.

For example, “I was at the Italian restaurant on Main Street for my birthday last year.” **Semantic memory is the store of knowledge we abstract about our world**. For example, “Italian restaurants typically serve spaghetti.”

On the other hand, **non-declarative memory is not conscious but implicit**, for example, riding a bike. It relates to knowing how to do something and is sometimes described as procedural. Amnesic patients can often form non-declarative memories even when their declarative memory is extremely restricted, confirming that storage and processing of both types most likely take place in different locations in the brain.

Amnesia patients

**Patients with amnesia offer the cognitive researcher great insight into our memory systems.** After all, if you know which areas of the brain are damaged, it is possible to map their functions via their deficits.

However, it may not be as easy as it sounds. Amnesia patients with a closed head injury often have multiple cognitive impairments, making it difficult to assess their memory deficits. Studying the memory difficulties associated with **Korsakoff’s syndrome**, the result of chronic alcoholism, has been helpful, yet its onset can be gradual, making it less clear which memories are affected.

Furthermore, **brain plasticity, the capacity of our brain to reorganize its structure, connections, and function, and the ability to learn compensatory strategies can further cloud the assessment of brain damage’s effect on long-term memory**.

The fascinating case of Henry Gustav Molaison

**Patients with amnesia offer the cognitive researcher great insight into our memory systems**. Scientists have learned much about human memory and the specialism of the brain from cases like **Henry Gustav Molaison**.

Having received surgery to his hippocampus for severe epilepsy, he was left with **significant language and long-term memory problems, yet his short-term memory remained intact**.

Henry had little knowledge of where he was or who cared for him and could not recognize the faces of anyone after the onset of his amnesia. His language production skills were also impacted, leaving him unable to plan and construct meaningful sentences when he spoke.

And yet he retained long-term memories and skills from before his surgery, and surprisingly, his short term memory appeared unaffected – performing well on drawing and short recall tasks.

Henry’s case, and others like his, provide strong support for the importance of the hippocampus to long-term memory and suggest that memories from before his surgery had migrated elsewhere in the brain and remained intact.

Memory and our mental health

When psychologist **Mark Williams** met with severely depressed patients, he was struck by their reporting of memories being **noticeably vaguer than a control group who weren’t depressed**.

Such findings led to the suggestion that being unable to recall specific events can increase the likelihood of depression. It seems that our memories may balance out our lives at times of stress, providing comfort when it is most needed.

Further research has added support to the idea that **memory problems can send our mental health into a downward spiral**, suggesting an opportunity to change the type of treatment offered to people at risk of depression.

While the theory has its critics, recent research with refugees suffering from trauma found that memory exercises significantly improved their mood and depression by giving them something to attach themselves to and the motivation to make life changes.

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