The different types of memory

Memory is a cognitive function that allows the brain to acquire, store, retain, and later retrieve information. It gives us the ability to remember past experiences, previously learned facts, experiences, impressions, skills and habits. It is the store of things learned and retained from our activity or experience.

There are three major processes involved in memory: encoding, storage, and retrieval. We tend to see memory as a computer memory system where everything is stored. In fact, it is much more complex than that. Memory is not a flawless process, people do not remember everything that has happened to them, and memories can change and become distorted. In other terms, memory is a set of encoded neural connections in the brain. 

There are different types of memory. Remembering what you ate at dinner differs from remembering the fact that London is the capital of the UK. The type of information being memorized or recalled engages the brain in different ways. Scientists have been studying memory for decades and several models have been proposed to classify the types of memory and explain its basic structure and function. In this module, we will rely on the stage model initially proposed in 1968 by Richard Atkinson and Richard Shiffrin that outlines three separate stages of memory: sensory memory, short-term memory, and long-term memory.

Sensory memory is the shortest form of memory and considered the first step of memory. It lasts only for a very brief period, usually no more than a second. 

Every day, your senses are constantly receiving an enormous amount of information about what you see, feel, smell, hear, and taste. While this information is important, it is impossible to remember every detail about what you experience at every moment. Instead, your sensory memory helps you piece together a sense of the world based on recent sights, sounds, and other sensory experiences, allowing you to briefly focus your attention on relevant details.

Some examples of sensory memory include:

• registering the sounds a person encounters on a walk
• briefly acknowledging something in a person’s field of vision
• the sound of your colleague typing on his computer next to you

Sensory memory allows us to briefly retain an impression of an environmental stimulus even after the original source of information has ended. Once we start paying attention to the source of information, we start remembering and we can then transfer important details into the next stage of memory, which is known as short-term memory. To give a concrete example, when a specific sensory experience becomes relevant, such as the smell of something in the kitchen, it may move to other types of memory.

Take a look at this video that explains what is sensory memory in two minutes: https://www.youtube.com/watch?v=tHwD5Ut0cmE

Short-term memory is the information we are currently aware of or thinking about. It stores information temporarily, 20 to 30 seconds, and then dismisses it or transfers it to long-term memory. 

Short-term memory is what we use to hold information in our head while we engage in other cognitive processes. In order to do that, we verbally or mentally repeat information to remember it. We repeat it without thinking about its meaning or connecting it to other information.

Examples of short term memory: 

• Remembering a string of 5–7 words and repeating it back
• Remembering a phone number long enough to make the call
• Shortly retaining information from a sentence that has been read, to make sense of the next sentence.

Short-term memories are quickly forgotten, attending to this information allows it to continue to the next stage: long-term memory

Watch: Short term memory explained in two minutes: https://www.youtube.com/watch?v=cnNx9R1At9s

Long-term memory is our brain’s system for storing, managing, and retrieving information. It has an unlimited capacity and duration. Long-term memories are a bit more complex than short-term memories. Anything that happened more than a few minutes ago is stored in long-term memory. The strength of the memory varies and depends on how often we recall or use a certain piece of information. 

Watch: Long term memory explained in two minutes: https://www.youtube.com/watch?v=mfDpXj67z2I

However, long term memory is complex and there are several types:

  3.1 Explicit

Explicit memory is a type of long-term memory requiring conscious thought. It is what most people have in mind when they think of a memory. It ca be conscious memories of events, autobiographical facts, or things a person learns. There are two types of explicit memory: episodic and semantic

  3.1.1 Episodic

Episodic memory includes the concrete experiences that we have lived. These are memories of events or autobiographical facts, they relate to our personal lives. Studies have shown that it is possible to reconstruct episodic memories, to adapt and change them depending on the context we recall them. Therefore, episodic memories are not always accurate. Our ability to retain episodic memories depends on how emotionally powerful the experience

Examples:

• What you had for dinner last night
• when you visited a certain city for the first time

• who you went to a certain party with

• The day you got married

  3.1.2 Semantic

Semantic memories are general knowledge about the world. A person may remember a fact or event that they did not experience because they learned or studied it. For example, you probably know what the human heart looks like because you have studied at school, you know the grammar rules of your native language, or you can list the capitals cities of Europe.

  3.2 Implicit

Implicit memories is information that you retain unconsciously and effortlessly. It is the things that you do not purposely try to remember that are stored in implicit memory. This type of  memories influence a person’s behaviour. 

Examples: 

• Riding a bike
• Speaking a language
• Driving a car
• Walking across your neighbourhood 
• Remember the lyrics of a song after hearing the first notes

These are skills that you learn and then do not have to relearn again in order to perform them.
The things you learned became automatic over time with repetition and you now do not need to think about the different steps you need to follow to perform a task.

   3.2.1 Priming

Priming is a part of implicit memory that subtly influences your behaviour and how you perceive the world. Priming means that you respond to a stimulus. For example, a smoker might crave a cigarette after a meal.

  3.2.2 Procedural

Procedural memory is a type of implicit memory made up of information of muscular movements that we have learned to automatize through practice. For example, learning how to walk, throwing a ball, or moving a computer mouse. At first, you had to learn to do these things and remember specific skills, but eventually, these tasks became an automatic part of procedural memory.

As we have seen, memory is a complex system that scientists have been studying for years. How can you improve your memory? Here are a few advices below:

• Get enough sleep. While we sleep, our brains process and store long-term memories.
• Minimise stress as it can alter the way information is stored
• Minimise distractions while learning new information: reduce noise, turn off your phone, etc. 
• Have a healthy diet. Scientists recommend eating foods high in antioxidants to keep the brain young and maintain memory function as we age.
• Play brain games. Exercise your brain just like you would do with your body.

Want to find out more ways to improve your memory? Watch this video: https://www.youtube.com/watch?v=NrEafQNV9KQ