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How the human memory works

By Jasper18 March 2020

memory cognitive skillWhen talking about memory, you probably think about remembering that unforgettable moment in life. Maybe you think about that happy childhood memory, or that person you used to know that was important to you. But memory is so much more than that. Reading, walking, recognizing the smell of your favorite dish, it is all made possible because of the memory. But what actually is the memory? How does it work? And why do we forget? In this article, we’ll explain you everything you need to know about the human memory. 
 

What is memory?

Our memory is our ability to encode, store and recall information from our brain.
But what does this actually mean? We will go through this process step by step:

  1. Encoding

All the information that our brain receives through our senses, will first be transformed into a form that the memory will be able to store. This event begins with perception through the senses. The way the information will be encoded depends on the kind of information it is and through what senses your brain receives it. In addition, what will be encoded to be stored within the memory can be affected by mood and stimuli. For example, a stressful situation can cause your brain to prevent you from storing memories at all.

  1. Storing

After all the received information encoded, the brain is able to maintain this information within the memory. But, there actually isn’t a specific place within the human brain where all the memories are stored. The different types of memories are stored across different interconnected regions of the brain.

  1. Retrieving

This stage refers to re-accessing the information that is stored within the memory. For example, when you think of a happy childhood memory you are retrieving information that was stored within your memory years ago. Although this might seem like a single memory for you, recalling a smell, sight, sound or feeling are all separate memories stored in different regions of the brain. When thinking of a certain memory, your brain digs into different parts of your brain and then connects all this information.
 

human memory definition

 

What is the purpose of memory?

Recalling the memories and experiences that are stored within our brain has the purpose of affecting future actions. If the already occurred actions wouldn’t be stored and couldn’t be recalled, it would not only be impossible to remember that happy childhood memory, but it would also be impossible to learn. For example, language skills, relationships or personal identity wouldn’t be able to develop.
 

What are the 3 types of memory?

Like already mentioned, the human memory doesn’t exist out of a single memory. It exists out of different types of memory systems. When we store a memory, we are receiving, encoding and storing information. How this information will be stored and for how long depends on what kind of information it is. Depending on the information, a different memory type will store the information.
There are 3 memory types, which have their own way of operating but still cooperate in the process of memorization. These types can be seen as the 3 steps that are necessary for creating a long-term memory. The 3 types of memory are the long-term memory, the short-term memory and the episodic memory.
 

3 types of memory
 

Memory type 1: Sensory memory

The sensory memory is considered as the first stage of memory. The sensory memory involves registering huge amounts of information about the environment, for a very short moment. It allows you to retain the information you receive through your senses after the original stimuli has ended. The process of receiving information through your senses is also called sensation.
It acts as a buffer for the stimuli received by hearing, seeing, feeling, smelling and tasting, which will be retained accurately but only for a couple of seconds. Whilst the senses are responsible for receiving all these stimuli, the stimuli are processed by your perception within your brain.
The sensory memory can be divided in the following 5 sensory memory systems:  

 

sensory memory types

 

  • Haptic memory (touch)

    The haptic memory recalls information that was originally collected by the sense of touch. When thinking of raindrops on your face, you might recall how this feels. This is made possible by the memory saving these types of information via the haptic memory.

  • Echoic memory (hearing)

    The echoic memory, also known as auditory sensory memory, is the sensory memory that stores sound. You can probably recall your favourite song as if it is on right now, this is a memory that’s been stored after being collected by the echoic memory.

  • Iconic memory (sight)

    The iconic memory is the sensory memory that stores visual information after receiving this information through your sight. While looking at your screen and reading this text, your iconic memory stores information for a couple of seconds. If you close your eyes, you can probably recall what you are seeing right now.

  • Olfactory memory (smell)

    The olfactory memory refers to the recollection of odours. When thinking of your favourite dish or flower, you might even remember the smell of that dish or flower. This memory has been stored within your memory through the olfactory memory.

  • Gustatory memory (taste)

    The gustatory memory is the sensory memory that is responsible for recalling taste. While eating or drinking, a lot of information is stored within the memory through our gustatory memory. You can probably remember the taste of your favourite dish, because the gustatory memory helped to store this information within your memory.
     

sensory memory

 

Memory type 2: Short-term memory

Your short-term memory is responsible for holding a small amount of information for a short period of time. This information is processed through the sensory memory in your short-term memory. The short-term memory holds this small amount of information in an active, quickly accessible state. The memories stored within the short-term memory will last for about 10 to 15 seconds.
Take remembering a phone number while you are entering the number before you call it. You read a couple of digits, try to remember them and enter the digits. At this moment you remember the digits and probably recalling the digits within your head, while you’ll forget them in the long term. In this situation, you are using your short-term memory.
 

The working memorythe working memory

The working memory is a memory system that is responsible for storing and managing information that is required together with other cognitive skills to perform cognitive tasks, such as learning and reasoning. The working memory focusses on memory-in-action, it has the ability to remember and use relevant information while in the middle of an activity.

 

The difference between your short term and working memory

The short-term memory and working memory sound quite similar to each other, both memory systems hold information for just a couple of seconds. Yet, the two memory systems are distinct. While the short-term memory only retains information, the working memory both retains and retrieves information. The working memory is used when performing a task where you have to remember and do something at the same time. Such as responding to something that has been said in a currently active conversation.

 

Memory type 3: Long-term memorylong term memory

The long-term memory is the memory system that stores information for a longer period. This duration might be from a few minutes to an entire lifetime. Information reaches the long-term memory by registering information through the sensory memory to the short-term memory, to be eventually stored within the long-term memory. But not all information will be stored within your long-term memory. Through the process of association and rehearsal, short-term memories might become a long-term memory.
The long-term memory exists out of the following 2 memory systems:

  • Explicit memory
The explicit memory is a conscious thought, which means that it’s the kind of memory that you use when recalling what you did last night or naming animals that live in the ocean. What most people have in mind when thinking about memory, is actually the explicit memory. The explicit memory exists out of the episodic memory and the semantic memory. The episodic memory stores personal experiences, such as that favorite holiday. The semantic memory stores factual information, such as the capital city of a country or the items on your shopping list.
  • Implicit memory
The implicit memory is an unconscious memory, it is what you aren’t trying to remember on purpose. These memories are stored unconscious and unintentional. The implicit memory makes priming, perceptual learning, category learning, emotional learning and procedural learning possible.
Within the implicit memory is the procedural memory. The procedural memory is responsible for storing information about how to do things, such as walking, talking or riding a bike.
 

memory types

 

How memory is processed

Like mentioned earlier, the three stages that are involved in remembering information are encoding, storage and retrieval. But how do we relate this to the sensory memory, the short-term memory and the long-term memory? We’ll go through the process of how a memory is stored from the sensory input to the long-term memory.

Stage 1: From environmental input to the sensory memory

A memory starts with information that is detected by the senses. After the information is being detected by hearing, seeing, smelling, feeling or tasting, it enters the sensory memory. This information will be stored for about half a second, before it’s forgotten. If the detected information is considered relevant enough to be registered, it will enter the short-term memory. Otherwise, it’ll be forgotten.

Stage 2: From the sensory memory to short-term memory

In order for the sensory memory to be retained for a longer period, it has to convert from the sensory memory to the short-term memory. Just like the sensory memory, the short-term memory only stores information temporarily. If not processed to the long-term memory, the information within the short-term memory will be forgotten after about 20 to 45 seconds. Unlike the sensory memory that stores the complete perception perceived by your senses, the short-term memory only stores your interpretation of the information.
The capacity of the short-term memory is very limited, most people are able to store between five and nine subjects. If these subjects won’t be processed into the long-term memory, your brain will usually forget them within a minute.

Stage 3: Short-term memory processed to the long-term memory

Although the memories in your short-term memory will be forgotten after about 20 to 45 seconds, rehearsal of the information converts it into the long-term memory. The information will be encoded by making judgements, assessments about meaning, by relevance and the significance of that information. If the encoding of information won’t happen, the information won’t be stored within the long-term memory.
The information that is stored within the long-term memory, can be retrieved for up to any duration. Different to the short-term memory, the long-term memory has an unlimited capacity Yet, the information that is stored within the long-term memory can be forgotten through interference or retrieval failure.


The stages of the memory process are visualised in the image below.

 
human memory process
 

Why do we forget?

Despite our long-term memory to have an unlimited capacity, it occurs that you fail when you are trying to recall some information. However, forgetting isn’t usually about actually losing or erasing this information from your long term memory. There are four major reasons why we forget, these are:

  • Retrieval failurememory forget

One of the factors that play a huge role in forgetting is time. When time passes, memories that have not been accessed could fade away. A memory can be stored and retrieved when you are learning something new or when you are connecting new information with existing memories that are already stored within your brain. If this information will not be retrieved and rehearsed over time, these memory traces will start to fade away. This is also called the decay theory.  This can be seen as a moment that was important to you a long time ago. At first, you remember everything about that moment, but after not thinking about it for years the moment starts to fade away.

  • Interference

Memories can also be forgotten because of interference. Some memories you have stored within your brain can interfere with other memories. This can occur when information is very similar to the other information within your memory. This is also called the interference theory. Maybe you have a memory of one of your holidays, which can be in fact a memory of another holiday. You can mix up the memory of these two similar situations, causing your brain to forget the original one.

  • Failure to store

It can occur that losing a memory isn’t caused by forgetting. Sometimes losing a memory happens because it never actually made it into the long-term memory at all. This is a result of the encoding that often fails, preventing information to convert from the short- to the long-term memory. Like when you are learning from a book and you thought you knew everything that was needed for a test, but suddenly the memory is gone. Failing to store a memory can have lots of causes, such as a stressful situation, learning from a book until your memory is overloaded with new information, lack of focus while you weren’t aware of it etc.
 
deleting human memory
 
  • Motivated forgetting

Sometimes we forget a memory because we actually try to forget it. These experiences might for example be traumatic or disturbing. There are two forms of actively forgetting memories, these are suppression and repression. Suppression is a form of conscious forgetting a memory, while repression is an unconscious form. Maybe you’ve experienced something traumatic or disturbing, such as an accident. While you might remember this situation in detail first, you may have forgotten most of this negative experience by now.

 

Causes of memory losscauses memory loss

Besides forgetting a memory as a result of the normal forgetting processes of the memory, there are many reasons that can cause memory loss. How these causes might affect the brain or if they even affect the memory at al differs per person and situation. A couple of examples of memory loss causes are:

  • As a result of a brain injury
  • Excessive use of alcohol
  • Brain infections such as Lyme disease
  • Overuse of medicines
  • Epilepsy
  • Mental illness such as Parkinson
  • Low levels of important nutrients and vitamins 

  

Can you improve your memory?

Because your brain adapts to different stimuli it gets (also known as neuro plasticity), it’s possible to improve your memory. You can do this by challenging your brain to force your memory to work. Besides challenging your brain, there is a lot you can adjust in your lifestyle to improve your memory. You can improve your memory by:

  • Learning something newimprove memory
  • Exercising
  • Social interaction
  • Healthy nutrition
  • Ensure enough sleep
  • Avoid stress
  • Preferably no alcohol
  • Use memory techniques
  • Brain training to challenge your memory 

 

Conclusion

Now you know that your memory isn’t just “your memory”, but actually the combination of your sensory, short-term and long-term memory. With them combined, your memory is able to process what your senses gather, define conclusions and store important information!