An article on human memory [videos]

Memory is simply a recollection of the past. It is the mental faculty involved in storing and retrieving data that had been encoded. This is vital to our learning process.

According to Oscar Wilde, an 1880s Irish poet and playwright, memory is something we carry like a diary… You constantly “write” what you experience and learn – every semantic, every episode and every procedure adds up into your little gray and yet powerful mental library.

Memory is the diary we all carry about with us.

Oscar Wilde

To Aldous Huxley, English writer and novelist, memory is one’s private literature… It is just like having a personal notebook with a key or a password-protected journal where all your secrets are compiled . . . until you decide to share it . . . or blog it…

Every man’s memory is his private literature.

Aldous Huxley
Memory is recollection of the past - the mental faculty for memorization and recall. I Call Her Mnimi -
Memory is recollection of the past – the mental faculty for memorization and recall.
I Call Her Mnimi |

Memory in Psychology

In Psychology, memory is defined as the ability to absorb information through three basic memory processes. These, which are oftentimes referred to as the 3 stages of memory, are encoding, storage and retrieval… So for every input, there usually is a normal sensory response and, depending on that person’s level of focus or interest, the reaction is stored into the brain and then recalled later.

Three (3) stages of memory

  • Encoding – initial response to stimuli that our senses are exposed to
  • Storage – storing of encoded information, involves the process of memory consolidation
  • Retrieval – recalling of stored information; that is, memory

Impairment to the above processes due to brain damage or any cognitive deterioration may lead to memory loss.

Making of a memory

How We Make Memories – Crash Course Psychology #13 by CrashCourse, on YouTube

Memory is extremely powerful. It’s constantly shaping and reshaping your brain, your life and your identity… Our memories may haunt us or sustain us; but either way, they define us. Without them, we are left to wander alone in the dark.

Kathleen Yale on How We Make Memories – Crash Course Psychology #13 [YouTube]

Atkinson-Shiffrin model of memory

There is a sequence of mental storages that explains the onset of memory registry.

In 1968, Richard Atkinson and Richard Shiffrin published the multi-store model or modal model. Labeled as the Atkinson-Shiffrin model of memory, it consists of…

Three (3) components within the memory system:

  • Sensory register – where memory is initially taken in and registered by the senses
  • Short-term store – where sensory perception is temporarily stored
  • Long-term store – where “rehearsed” memories are transferred to and retrieved from

In other words, gathered sensory information is transferred from its register to short–term memory. Atkinson-Shiffrin postulated that such input will then be transferred from short–term to long–term storage by way of active repetition or rehearsal. (6)

3 stages and types of memory

There are three major stages of memory – starting from the sensory register that lasts no more than 4 seconds. If given attention, it becomes short-term, lasting for just a little bit more and, when the brain further processed by repeating or rehearsing it, may lead to long-term memory.

These 3 stages are broken down into each type.

Sensory memory

Sensory Memory by DARKMATTER Creative Commons – Copyright Free Music Library, on YouTube

Sensory memory (SM), lasting from a split second to four, is the shortest-term among the three stages. Such fleeting memory is an automatic response to stimuli perceived by our five senses – sight, hearing, smell, taste and touch.

The part of the brain responsible for processing sensory input is the temporal lobe. Located on the medial temporal lobe are two key players in memory retention and recollection – hippocampus and amygdala – which are further explained far below…

An example of sensory memory is a never-before-seen picture flashed at you or a new instrumental briefly played. You may vividly remember how it looked or sounded but only for that particular moment. That memory fades away as time passes.

It was like trying to recall a forgotten dream. Each time I felt close to remembering where we’d met, the memories slipped away.

Michelle Madow, Remembrance

Iconic sensory memory

Iconic memory refers to our sense of sight – icon, being a form or image. It is the auto-response to any visual stimulus that quickly degrades in less than a second.

Examples of this visual memory are remembering the faces of twelve people you just met and describing what they wore.

Sperling’s iconic memory test

In 1963, George Sperling, an American cognitive psychologist, experimented on visual and auditory persistence. He first used the free recall – a technique in which a tachistoscope displayed a three-row grid lined up with three letters. After flashing all nine characters to participants, they were immediately asked to recall as many as they could. Sperling found out that people can only remember 4 to 5 letters.

The said procedure, now known as the Sperling’s Iconic Memory Test, evidently showed that visual information quickly fades away, such that a person will not be able to recall every single thing regardless if the entire image has been seen.

Then in 1967, Ulric Neisser “proposed this label to convey the idea that iconic memory preserves an exact duplicate of the image falling on the retina.”

Tachistoscope [image] - a device that displays an image for a specific amount of time; used by George Sperling in his free recall experiment

Echoic sensory memory

Echoic memory is the auditory sensory memory. Just as echo refers to the reflection of sound, this type resonates in the mind right after sound exposure.

Also coined by Ulric, echoic memory is estimated to last up to 4 to 5 seconds so it is a little longer than iconic memory. This is because the eardrum cause vibrations through the cochlea.

When you see a phrase of words or set of numbers, have you said those out loud to better remember?

Sperling made a study variation of the free recall by testing with sounds. In his cued recall test, three rows that were lined up with four letters each had a particular pitch. He found out that participants can recall more by listening as opposed to seeing.

Olfactory sensory memory

How Many Smells Can You Smell? by t’s Okay To Be Smart, on YouTube
How Smells Affect Your Memory 👃 | BRAIN GAMES by National Geographic Kids, on YouTube

Olfactory memory is the recollection of odors.

Although our sense of smell falls under the shortest-term memory category, our odor stimulants tend to be processed further by the brain. When inhaling someone’s perfume, for instance, we may remember or associate that scent to that person later on.

Anatomy of a smell

  • Why is scent so closely associated with memory?
  • Why do certain smells make you remember?
  • What triggers memory recall?

When we smell an odor, it leads up from our nose to the olfactory bulb, the part of the forebrain that contain neurons responsible for olfaction or smelling. This is connected to the amygdala (pronounced as əˈmiɡdələ), the almond-like gray matter involved in emotional learning, and is situated close to the hippocampus (pronounced as hipəˈkampəs), the seahorse-shaped structure essential for memory consolidation.

Amygdala - Latin for almond
Hippocampus - Latin for seahorse / hippos (horse) + campus (sea monster)

Have you smelled home-baked cookies and thought of your grandma? How about a whiff of fresh pine that takes you back to your childhood Christmas?

Nothing is more memorable than a smell. One scent can be unexpected, momentary and fleeting; yet, conjure up a childhood summer beside a lake in the mountains.

Diane Ackerman

Gustatory sensory memory

Gustatory or gustation is the faculty of tasting. Simply put, gustatory is taste memory or, as others say, food memory.

For the most part, taste and smell work closely together. In fact, when we are sick with a cold, we can not taste the food.

What is even more interesting is that taste is influenced by the other senses such that cheesecake tastes sweeter on a white plate than in a black one. This interaction between two or more sensory inputs is called cross-modal interaction or cross modal perception.

Did you know that 80% of the flavors we taste come from what we smell?

Haptic sensory memory

Also known as tactile memory, haptic memory pertains to the touch stimuli.

The Future of Haptic Touch Beyond Apple Watch | WWDC 2015 | The New York Times by The New York Times, on YouTube

Take the haptic technology for example. Virtual reality headsets as well as VR rides stir your emotions that will make the experience long-lasting and more memorable. Apple watches and iPhones simulate vibrations that may perhaps allow you remember to buy the next upgrade.

But electronics aside, some people are fond of paper on their hands as they flip pages of books that remind them of some lovely days of old…

All of us, who grew up reading comics, love the memory of sitting under an apple tree with a comic book in one hand and a peanut butter sandwich in the other. The tactile sensation of the paper on the skin and so forth is part of the experience.

Mark Waid quote

Short-term memory (STM)

Short-Term Memory and Working Memory (Intro Psych Tutorial #72) by Michael Corayer, PsychExamReview, on YouTube

Short-term, primary or active memory is defined as the temporary holding capacity of information. It works as a storage system in the brain for a limited period of time.

Lack of attention is one reason why we forget. So, by paying attention to the senses registered, raw data will move into the short-term store. This, however, does not last very long. Atkinson and Shiffrin estimated that STM lasts about 15 to 30 seconds.

The average person’s short-term memory can hold only five to seven bits of data at any one moment. If you put more items in, others fall out. The older you are, the more you have crammed into those memory circuits. Twenty-five-year-olds can remember things because they still have empty space. Some of us take our children to the supermarket in the hope they will remember why we are there.

Jennifer James

Miller’s magic number

In 1956, George Miller presented his magic 7 plus or minus 2. In this so-called Miller’s law, he estimated that most people can remember about 5 to 9 items; that is, an average of 7 highly volatile data.

Short-term memory vs. working memory

In the primary STM stage, information that is active in the mind are not manipulated but merely being held temporarily; whereas in working memory, its structure is not only holding data but also manipulating those.

In other words, while short-term memory is the current thought, working memory is memory in action. One good example of this is when a ballerina recalls all her moves whilst dancing or when a guitarist finds his way to press the right strings.

Baddeley-Hitch working memory model

Working Memory, Baddeley & Hitch 1974, Memory, Cognitive Psychology by Psychology Unlocked, on You Tube

In 1974, Alan Baddeley and Graham Hitch, both British psychology professors, proposed their 3-part model of working memory. The three main components are: central executive, phonological loop and visuospatial sketchpad. In 2000, Baddeley added the episodic buffer as the fourth component that is under the slave system.

  • Supervisory system
    • Central executive – the decision-maker
  • Slave systems
    • Phonological loop
      • Articulatory control system – inner voice
      • Phonological store – inner ear (not the physical ear canals)
    • Visuospatial sketchpad – holder of visual information
  • Episodic buffer – link to all the elements of working memory

Supervisory system

Central executive

Under the supervisory system is the central executive, the most important part of the working memory as it has complete control of the actions of the other components. It “supervises” the slave systems and makes decisions.

Slave systems

Phonological loop

The phonological loop is part of the working memory model that represents a temporary store with the purpose of remembering verbal information through rehearsal or (mental) repetition.

For example, upon hearing a phone number, you may verbally say or “loop” it in your head until you are able to save on your phone. If you lose attention or get distracted, chances are you will forget.

Two phonological loop components
Articulatory control system

The articulatory control system is the inner voice that revives 2-second memory traces with all auditory information believed to directly enter the phonological store. It is also called the articulatory rehearsal component or the articulatory loop.

Phonological store

The phonological store is virtually referred to as the inner ear where traces of auditory memory quickly fades away.

Visuospatial sketchpad

The visuospatial sketchpad is also an element of working memory that functions as the visual info storage and processor. It is the one that remembers colors and shapes.

The capacity to identify visual and spatial relationships – differences and similarities – among objects is called visuospatial memory or visuospatial cognition.

Episodic buffer

The episodic buffer, as Baddeley envisioned it, is the system that stores information fed by the visuospatial and verbal subsystems, as well as perception. Linked to the central executive, it plays a crucial role in conscious awareness.

Furthermore, the episodic buffer temporarily holds information in a multi-dimensional way – both visual and verbal – combining data into chunks or episodes. In other words, it functions as the link to all the elements of working memory in preparation for long-term memory storage.

It is a buffer in the sense that it holds information temporarily… It is episodic in that it binds things together in chunks or episodes.

Alan Baddeley on episodic buffer via YouTube

Short recap:

  • Our sensory memory has the capacity to register information that decays rapidly.
  • Once attention is given, that sensation moves to our short-term memory store.
  • When further processed by the brain through rehearsal, whether verbal or mental repetition, it moves into our long-term memory storage for later retrieval.

You have to have short-term memory. You have to be able to move on to the next practice, the next game, turn the page and keep your emotions so you make the decisions that are best for your group.

Randy Carlyle

Always carry a notebook and I mean always. The short-term memory only retains information for three minutes. Unless it is committed to paper, you can lose an idea forever.

Will Self

Actually, if you commit yourself to processing that idea further in your brain through repetition or rehearsal, short-term memory may lead to long-term…

Long-term memory (LTM)

How Does Our Brain Store Memories? by WASTETIME, on YouTube

Long-term memory is the unlimited store that is capable of holding information for a long period of time. To have LTM means being able to to remember things long after those were absorbed. This is key to learning and may very well be associated with intelligence – the ability to remember ideas.

There are three types of long-term memory and those are episodic declarative memory, semantic declarative memory and procedural memory. While episodic and semantic memories are explicit, procedural memories, such as learned motor skills, are implicit. Below is how these are outlined:

  • Long-term memory (LTM)
    • Explicit memory or declarative memory
      • Episodic declarative memory
      • Semantic declarative memory
    • Implicit memory or procedural memory


The part of the brain responsible for long-term memory is the hippocampus. This brain matter, so named because of its seahorse shape, plays an important role in converting short-term memory into LTM. When it “aggregates” and “glues” short-term memories” through consolidation, long-term memories are stored all across the brain cortex, the largest part of the cerebrum.

Inside the cerebral cortex, long-term memory persists and the duration is indefinite. The LTM store is unlimited. But although its capacity may last a lifetime, it may also be semi-permanent through brain damage and memory loss.

Memory Consolidation - the process of memory retention where short-term memory is converted to long-term memory.

Declarative or explicit memory

Who are you? Where do you live? When were you born?

The answers to the above questions are examples of declarative memory. Your full name, address and birthday are explicit information that you declare. This type of long-term memory refers to facts and events you consciously know. In Psychology, declarative memory is subdivided into two – episodic memory and semantic memory.

Episodic memory

Episodic memory refers to episodes, that is, recalling time, places, emotions and other things relevant to that event. It is unique to that person who remembers it. Because this forms part of someone’s life experiences, such memory becomes particularly important.

The parts of the brain associated with episodic memory are the hippocampus and amygdala. While the former consolidates your new memory, the latter stores your emotions, specifically fear.

Semantic memory

Semantic memory refers to general information in the long-term store. Unlike episodic memory, this type of explicit memory does not relate to any personal recollection.

Here are examples of both semantic and episodic memories respectively… There was a total solar eclipse on August 21, 2017 that occurred in Corvallis, Oregon. I remember waiting at a parking lot and feeling excited to witness that for the first time!

Procedural or implicit memory

You are at a party and, suddenly, line dancing starts. Your friend pulled you from your seat and taught you the foot work. Before long, you are already following every single step as if you had danced to that music before. Enjoying every beat, your entire body unconsciously sways as you get deeper into your rhythm. This is implicit or procedural memory.

Procedural memory refers to recalling a procedure – how things are done. It is also called bodily memory, muscle memory, motor memory or motor skills.

The part of the brain that is responsible for procedural memory is the cerebellum, that “little cerebrum” at the back of your skull that is most involved in motor control, as well as creating and recalling implicit skills.

While explicit memory is the you-know-what, implicit memory is the you-know-how. It is implicit such that you can perform the task without thinking consciously about it.

In the above example, your body “unconsciously” sways deeply into the music. Another examples of implicit memory are walking and the piano skills you learned during childhood. You may even have a habit of scratching your head as you read this without knowing until someone points it out to you… 🙂

Atkinson-Shiffrin memory model,–Shiffrin_memory_model
Bradley’s model of working memory,
Human memory – definition of Human memory by The Free Dictionary by
Declaratuve (Explicit) & Procedural (Implicit) Memory,
George Sperling,
Short-term memory,
Short-Term Memory Duration and Capacity, Cherry, Kendra, updated April 27, 2018
Three Stages of memory in Psychology: Explanation & Summary,
Working memory model,
(6) White, Aaron. (2003). What Happened? Alcohol, Memory Blackouts, and the Brain. Alcohol Research & Health, 27(2), 186-96. Retrieved from