A deep dive into memory

Major memory systems in more detail

Sensory memory

As defined by Dr. Robert Siegler “Sensory memory is the capacity for briefly retaining the large amounts of information that people encounter daily”. The information can be classified into 3 categories.

1.???? Information gathered from sight (Iconic memory) – for example seeing your friend trip over a step and remembering that next time you are heading that way. Allowing you not to trip over.

2.???? Information gathered from hearing (echoic memory) – for example looking through a window and hearing the slap of the floor when your friend has fallen and the people laughing around them. Whilst not seeing the incident, you remember the sound of laughter which reminds you to pick up your feet while you walk.

3.???? Information gathered from touch (haptic) – For example reaching into your bag and feeling a fluffy fury little object and remembering that you have a key ring that is that texture – rather than it being a dead mouse given as a present from your cat.

Short-term/Working memory

A system of the brain that provides temporary storage of information gathered from the world. This temporary storage allows the brain to manipulate such information to use for demanding tasks such as understand language, learning and reasoning. For example, learning a new word in French and understanding its meaning in a sentence a few moments later.

It is further divided into sub-systems that are responsible for various information. Let’s have a look

4 systems of the working memory

1.???? Central executive system: This system controls attention but has a limited amount of capacity to process information. Actions are controlled in two ways – behaviours that are mundane and routine are controlled automatically by learned processes that allow us to carry out thoughts and movements relevant to our task.

Or behaviours that are not automatic and that require extensive thought and planning. It is helped by long-term memory that assists with new solutions to a problem or a situation before deciding on a response

2.???? Visuospatial system: The storage of information gathered from observing an object and its features. For example – remembering that the bag you liked had a cute little rose painted on it.

3.???? Phonological buffer: It is argued that this system supports acquisition of language by allowing the brain to store new words, while they are stamped down in our long-term memory. Phonological buffer is the short-lived ability of the brain to hold a word or a sentence before it is said out loud. For example – being asked to name list of cars you have owned.

4.???? Episodic buffer: This system is a temporary storage capable of blending information from various sources. It is episodic in a sense that it holds episodes of information that is blended across a situation. For example – someone saying two giraffes and you seeing them on the screen. Essentially episodic buffer is a system that creates a memory by using more than two sources of information.

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Long term memory

This is referred to as the memories that last. Unlike working/short-term memory where scenarios are only held for a brief moment – long-term memory can maintain information for months, years or even a lifetime. There are two types of – declarative or explicit memory and non-declarative or implicit memory.

Declarative/Explicit memory

Information that can be consciously remembered such as your wild 18th birthday or knowing that the grass is green and the sky is blue. It can be further divided into 2 subgroups. Episodic and Semantic.

1.???? Episodic

“Episodic memory involves the ability to learn, store, and retrieve information about unique personal experiences that occur in daily life. These memories typically include information about the time and place of an event, as well as detailed information about the event itself.”

Said Dr Dickerson

This can be the face of your dad when you come back home from that 18th birthday party. This memory can be extremely vivid as it caused an emotional response, such as fear or guilt. It has been proven by laboratories of James McGaugh and Larry Cahil that memories that evoke emotions are more easily remembered by the brain due to the link between adrenaline and memory.?

The regions of the brain responsible for declarative/explicit memories are:

• Cortex
• Peripheral cortex
• Entorhinal cortex
• Parahippocampal cortex
• Circuits withing medial temporal lobe & hippocampus

2.??? Semantic memory

The ability to reason, plan for the future and reminisce about the past are all dependent on our beliefs and concepts stored in our semantic memory. These types of memories also store factual information, such as, the colour of the grass and the sky or knowing how to use a pen. It also plays a major role in speech as it helps to remember words and helps to put them into a sentence.

Non-declarative/implicit memory

Implicit memory stores all unconscious memories, such as certain abilities, technique, skill & expertise. There are four types of implicit memory; procedural, associative, non-associative, and priming. These are responsible for our habits and other automatic behaviours that we will be discussing in detail below.

Procedural: Responsible for our habits and skills

Procedural memory is involved in remembering movement, co-ordination and executive skills to perform a task. Such as riding a bicycle – it guides activity and usually works automatically, without thought. When needed, procedural memories are recalled unconsciously to be used in complex movements and intellectual skills.

Improvement of skills that require intense cognitive input or precise movement occurs through procedural learning – whereby, we repeat a complex task or activity until the neural systems involved work efficiently and automatically. This is where practice comes into play. To learn a musical instrument or to pass your biology test we need to expose our minds to the information so that the recall can become more efficient.

Associative memory

A storage and retrieval of memories through the combination of other information. The acquisition of associative memory is carried out by two types of training - Classical and operant conditioning.

Classical conditioning: Learning between a stimuli (sound, taste, touch etc.) and behaviour. For example, a cat learning that the rattling noise of the box of dry food means meal time or when school bell rings you know its time to run out of the class.

Operant conditioning: A form of learning in which new behaviours develop due to the consequences – negative or positive. For example, by studying very hard for an exam and getting a good result you learn that sacrificing some of your free time now leads to success later.

Non-associative memory: Habituation & sensitization

Newly learned behaviour through repeated exposure to a task. Habituation is linked to repetition. The repeat of an action leads to a decrease in it response. For example, a new alarm sound may wake you up instantly – but use it for a year and you’re body will get used to it and may choose to ignore it from time to time leading to you oversleeping.

It is believed that habituation is due to depressed signals from our nerve cells as a result of repeated activation – leading to less efficient communication between the cells.

Sensitization on the other hand is an increase is response to a stimuli due to the repeated exposure. For example, increased back pain every time you try to tie your shoes. Your nerve cells become more responsive and more efficient at letting you know that there is something wrong and that bending down makes it worse.

Priming

Is when an exposure to a certain stimulus (words, movements etc,) will increase the chance of you using it later.?

For example. If you present a list of words to a person that contains the word ‘ball,’ and then the person is asked to participate in a task to complete words, they are more likely to respond with the word ball to the presentation of the word bowl than if they had not previously seen that word in the original list. Thus, the priming capacity can affect the choice of a particular word on a test to complete words, even long after conscious recollection of the primed words has been forgotten.

Final thoughts – what we have learned

In this article we learned everything about memory. We now know that there are 3 major systems; Sensory memory, working/short-term memory & long-term memory. They are all responsible for storing different information. We also learned how complex they are and that they have sub-systems within to help make sense of the world and that they are influenced by our lives. What we do, who we meet and what we learn is what makes us – us.

References:

• Camina, E. and Güell, F., 2017. The neuroanatomical, neurophysiological and psychological basis of memory: Current models and their origins.?Frontiers in pharmacology,?8, p.438.
• Dickerson, B. C., and Eichenbaum, H. (2010). The episodic memory system: neurocircuitry and disorders.?Neuropsychopharmacology?35, 86–104. doi: 10.1038/npp.2009.126
• Haluts, N., Trippa, M., Friedmann, N. and Treves, A., 2020. Professional or amateur? the phonological output buffer as a working memory operator.?Entropy,?22(6), p.662.
• Siegler, R. S., and Alibali, M. W. (2005).?Children Thinking.?Upper saddle river, NJ: Prentice Hall