photographs memory

The Psychology of Memory

Memory is a complex process that we take very much for granted. Imagine what life would be like if you didn’t have a memory. You would have zero recollection of what happened to you ten seconds, minutes or years ago. Without memory, every moment would be a new experience (and not in a good way, but in a bad ‘who am I and what am I doing!?’ way). Every person you met would be a total stranger and each task you attempted, would probably be a struggle to say the least. Even basic tasks such as brushing your teeth or putting your clothes on would be difficult without assistance, as you would have no memory of how to do them.

You would not be able to hold a conversation and you would have no friends because you would have no memory of ever having met a person. Without memory you would have no self-concept or personal identity, which develops through the many experiences and memories we have throughout our lives. Without any of these we would have no basis for developing an understanding of who we are. Every time you looked in the mirror you would confront a complete stranger. It is memory that allows us to integrate our thoughts with the past, present and future. Without it we would be nothing, but it also has it’s negatives.

Table of Contents

  1. Representations of Memory
    1. Mental Representations
    2. Sensory Representations
    3. Verbal Representations
  2. The Anatomy of Memory
  3. Sensory Registers
  4. Short Term Memory
  5. Long Term Memory
  6. Evolution of the Model
  7. Working Memory
  8. Declarative and Procedural Memory
  9. Explicit Memory
  10. Implicit Memory
  11. Past, Present and Future Memory
  12. Organisation of Long Term Memory
    1. Levels of Processing
    2. Networks of Association
  13. Remembering and Forgetting
    1. Why Do People Forget?
memory loss depression

Representations of Memory

The psychological concept of memory involves taking something we have observed – whether it be a smell, a sound, or sight, or a combination of the three – and converting it into a form we can store, retrieve and use.  The following post on memory will briefly consider the various ways the human brain can preserve the raw material of memory, and also explore the evolving model of information processing that has guided psychologists’ efforts to understand memory for the last quarter of a century. and organised in long term memory

Mental Representations

For a sound, image or thought to return to mind when it is no longer present, it has to be represented in the mind without the original stimulus being present. Therefore your mind literally recreates the memory based on your storage of it. The three main memory storage systems are sensory, verbal and motor (physical actions).

Sensory Representations

  • Sensory representations store information in a sensory bank, such as the sound of an ocean wave, or the image of a dog on a leash.
  • People rely on visual representations to be able to recall how to walk to the train station for example.
  • Visual representations are like pictures that can be mentally examined or manipulated.

Verbal Representations

  • Although many representations are stored in sensory modes, much of the time people think using verbal representations – information stored in words.
  • Try to imagine something in your mind without thinking it out with words, hard right? It’s almost impossible to think with sounds and images alone, as the mind works hard to make sense of your memories by describing them with words.

The Anatomy of Memory

In 1890 William James proposed a distinction between two kinds of memory, which he called primary and secondary memory. Primary memory is immediate memory for information momentarily held in consciousness, such as a telephone number. Secondary memory is the vast store of information that is unconscious except when called back into primary memory. This system for describing memory was called the standard model of memory and it looks a little something like this:

Standard Model of Memory

Basically the process for memory is as follows:

  1. Stimulus enters the sensory registers.
  2. Some information enters short term memory and is then passed on for storage in long term memory.
  3. Information can be lost from any of the sensory stores, usually if it is not important or if a traumatic event has interfered with memory consolidation/retrieval.
  4. Short term memory can be rehearsed to keep it in there longer and to help consolidate the information for long term memory storage – for example, if you’re told a phone number and you haven’t got a pen, repeating it in your head will keep it in your short term memory until you can write it down, after a bit of rehearsal it might end up in long term memory and you will be able to recall it easily.
  5. Consolidated information in long term memory storage can be retrieved and brought back to short term memory with the help of retrieval cuesimages, words, sounds, smells or actions that trigger past memories.
The standard model of memory has likened the processing of information in memory to that of a computer.

Sensory Registers

Sensory registers hold information about a perceived stimulus for a fraction of a second after the stimulus disappears, allowing a mental representation of it to remain in memory briefly for further processing. It contains two storage spaces, they are:

  1. Iconic Storage – briefly holds visual information – people retain a mental image of what they have seen shortly after it disappears from their vision.
  2. Echoic Storage – briefly holds auditory information – this is how you are able to hum the melody of a song you just listened to for example.

Short Term Memory

Short term memory (STM), is a memory store that holds a small amount of information in consciousness – such as a phone number – for 20 to 30 seconds, until the person makes a deliberate effort to maintain it longer by repeating it over and over.

Limited Capacity – Short term memory has a limited capacity, that is it can’t hold too much information at a time. To assess the capacity of STM, psychologists assess participants digit span, that is the number of numbers a person can hold in their mind at once. It has been established that the average person can hold 7 pieces of information in their short term memory at a time, with a normal range of 5 to 9 items.

The easy to remember formula for this is 7+/- 2 (7 plus or minus 2). You might be thinking to yourself, wait a minute… my mobile number is about 10 digits long, how can I possibly keep that many digits in my short term memory? We do this by utilising a little tool called chunking.

Basically, we can hold 5-9 pieces of information in our short term memory at a time, but this also includes chunks of information. So in the case of a mobile number of 10 digits such as: 0428790526, we instead remember it like this 0428 790 526, this chunks the ten digits into three easy to remember chunks of information, allowing us to hold more in our short term memory.

Rehearsal – People can control the information stored in short term memory. If I tell you my phone number and ask you to remember it and then I start counting backwards from 100, I can potentially mess with your short term memory; placing different numbers in your head space. Assuming I tell you my phone number, and decide not to mess with your head, you can repeat the number over and over again until you find a piece of paper and a pen to write it down.

This kind of repetition to maintain information in your STM is called maintenance rehearsal. Rehearsal is also important if you want to commit the information to long term memory, for example if you have ever needed to memorise lines from a play, you would know that simply repeating the lines over and over won’t help commit the memory. You have to say them out loud, in character and reflect on the meaning of each word and the emotions implied.

This is a much more elaborate method of rehearsing rather than just repeating the information in your hand, and so it is fittingly called elaborative rehearsal. Rehearsing information this way is much more likely to be committed to long term memory, another example of elaborative rehearsal ; teachers use this method frequently to remember their student’s names: “Dan the Man”, “Red Fred” etc.

Long Term Memory

While most information drops out of memory after it is no longer of use, more important information gets stashed away in long term memory (LTM), where representations of facts, images, thoughts, feelings, skills and experiences may reside for as long as a lifetime. According to the standard model, the longer information remains in STM, the more likely it is to make a permanent impression in LTM.  Recovering information from LTM, known as retrieval, involves bringing it back to STM.

  • Why does psychology distinguish between long term and short term memory? Simply because STM is brief, limited in capacity and quickly accessed. While LTM is enduring, virtually limitless, but more difficult to access.
  • Another reason emerged as psychologists tested memory using free-recall tasks. In free-recall tasks, the experimenter presents participants with a list of words, one at a time, and then asks them to recall as many as possible. When the delay between presentation of the list and recall is short, participants demonstrate a phenomenon known as the serial position effect: a tendency to remember information towards the beginning and end of a list rather than in the middle.

The reason we have this process for interpreting and storing memory is that in any given second we are exposed to countless sounds, images, smells, sensations all in one instant. If we were to take in every scrap of sensory information that surrounded us, our brain would probably shut down due to sensory overload. This is why we only acknowledge a small fraction of sensory information which stores in the sensory registers, while the important information in that cluster goes into short term memory for immediate attention, and very important information gets filed away in long term storage.

To illustrate the process of memory imagine a scenario where you and a friend are at a park on a windy day. The sound of the wind is intense, the birds are chirping, you can hear people talking the the background, cars driving on the street nearby, dogs barking and so on. You can also see all of these things, and can even see things in the distance that you cannot hear. On top of this you can smell the air, the cigarette smoke of a nearby smoker, the food in your friend’s hand etc. Our mind is incapable of processing all of this information at one time, which is why only immediately important sensory information is processed, while the words your friend speaks to you are immediately transported to short term memory, so you can dwell on what they have said before responding.


As the conversation flows and you become more involved in it you might find yourself blocking out other sensory information, and might forget that there are dogs catching frisbees nearby for example. Also, as the conversation grows and changes, you will find that your short term memory is no longer processing what you two were talking about 10 minutes ago for example, and is no busy concentrating on what you are currently talking about. This is because information leaves short term memory when it is no longer of use to the current situation. If your friend were to tell you something extremely important, then you might transfer that information into long term memory storage, so that you can never forget it.

Evolution of the Model

Even though the standard model provides a basic foundation for thinking about memory, in the last decade it has evolved in two major respects.

  1. Firstly, the standard model is a serial processing model: it proposes a series of stages of memory that occur one at a time in a particular order. Research has found that a serial processing model cannot provide a full account of memory for two reasons:
    • Most sensory information is never consciously (placed in STM) but it can nevertheless be stored and retrieved.
    • The process of selecting which sensory memory to store in STM is actually influenced by LTM, that is we can only decide how to filter information from the sensory environment by comparing that information with the information stored in our LTM. In other words, we cannot decide whether sensory information is valuable – and therefore necessary to be placed in short term memory – unless we cross check it with past experiences located in our long term memory.
  2. And lastly, researchers have come to view memory as involving a set of modules– discrete but interdependent processing units responsible for different kinds of remembering. These modules operate simultaneously rather than serially. For example:
    • Say you were to simultaneously hear thunder and see lightning, you would identify the sound using auditory modules in your temporal cortex, and you would identify the image as lightning using visual modules in your occipital and lower temporal lobes, and pinpoint the location of the lightning using a visual-spatial processing module that runs from the occipital lobes through the upper temporal and parietal lobes. When you remember this episode (the lightning/thunder that is), all three modules will be activated at the same time and you will have no awareness that these memory systems have been operating in parallel.

Working Memory

Because people use STM as a ‘workbench’ to process new information and to call up relevant information from LTM, many psychologists now refer to STM as working memory – the temporary storage and processing of information that can be used for problem solving and various other mental tasks.

  • Information stays in working memory only as long as the person is consciously processing, examining or manipulating it.
  • Like the older concept of STM, working memory includes both a temporary memory store and a set of processes designed for mentally manipulating information temporarily held in that store.
  • Recent research suggests that working memory contains three memory systems: a visual memory store, a verbal memory store, and a central executive that controls and tweaks the information contained in these two stores.

Central Executive – Processes such as rehearsal, reasoning and making decisions about how to balance two tasks simultaneously are the work of a central executive system that has its own limited capacity, independent of the information it is storing or holding momentarily in mind.

Visual Memory Store – The visual memory store, also called the visuospatial sketchpad is a temporary image that a person can hold in the mind for roughly 20-30 seconds. It temporarily stores visual information such as the name and location of objects in the environment, so that, for example, a person could get a bottle of milk from the fridge, and remember where their bowl of cereal was left on the table. Images in the visual store can also be mentally rotated and moved around.

Verbal Memory Store – Within the verbal memory store, words are stored in order, based primarily on their sound rather than their meaning. Researchers have found that a list of similar sounding words (such as man, cap, map  and pat) are more difficult to recall than a list of words that do not sound alike.

Declarative and Procedural Memory

There are two kinds of information that people generally store, they are declarative and procedural memories. Declarative memory is any factual information that can be stated or ‘declared’, such as your age or your address.

Procedural memory is any procedural knowledge or skills, anything that we know how to do, such as playing the guitar or typing on a computer keyboard. Declarative memory can be generic or episodic. Generic memory refers to general world knolwedge or facts, while episodic memory consists of memories of particular events.

Explicit Memory

Explicit memory Involves the conscious retrieval of information. There are two types of explicit retrieval: recall and recognition.

  1. Recall is the spontaneous conscious recollection of information from LTM, this is the memory retrieval that occurs when two friends talk about ‘old times’ for example. Although recall occurs spontaneously, it still requires conscious effort to dig up from LTM. If you don’t have the right cues to signal recall then you will experience what is known as the tip of the tongue phenomenon, which is when you know the information is somewhere in your brain, only you can’t retrieve it.
  2. Recognition is the recollection that something currently perceived has been previously encountered or learned. For example, when you answer multiple choice questions on an exam you are using recognition to retrieve information from your long term memory, as you only have to judge the correct answer out of a selection of answers. On the other hand, an essay question only prompts recall from long term memory, as you are required to write the essay yourself and remember the information to write the essay with limited information (the essay question).

Implicit Memory

Implicit memory involves memory expressed in behaviour, it is seen in physical skills and in associative memory learned through conditioning, such as avoiding certain activities that cause distress. Implicit associative memory emerges in experiments on priming effects, in which prior exposure to a stimulus facilitates or inhibits the processing of new information.

Long term memory semantic mind map

Past, Present and Future Memory

Everyday memory refers to memory as it occurs in daily life. Everyday memory is functional, focused on remembering information that is meaningful. Retrospective memory is memory for things that have occured in the past, while prospective memory is memory for things that need to be done or accomplished in the future.

Organisation of Long Term Memory

For information to be retrievable from memory, it first must be encoded, or converted into a readable format for the brain to be able to access. The manner of encoding, or the effort a person makes to learn new information, has a substantial influence on how accessible the information is for later retrieval.

Levels of Processing

Level of processing is the degree to which information is elaborated, reflected on and processed in a meaningful way. The two levels of processing are shallow and deep.

  1. Shallow processing is processing at a structural level, this is when only physical characteristics are noticed by the observer.
  2. Deep processing has two levels, the first is at a language level – the observer processes words and sounds, while the deepest level is called the semantic level, this is when the observer processes the meaning of an object.

Generally information is more sound if it is processed at a deeper level, especially when the new information is consciously linked to or compared with previous knowledge – this is why it is almost always helpful to use examples or analogies to process and link up new information with old. However, sometimes shallow processing can be more beneficial than deep processing, depending on what sort of information needs to be retrived. For example, shallow processing might help you out with answering multiple choice questions on an exam, while deep processing would be more effective for an essay question. This is known as the encoding specificity principle.

Context and Retrieval –

  • The context you are in when you are encoding new information has an effect on how you retrieve it, if you are angry when you learn something for example, then you are far more likely to retrieve that information at a later date, when you are angry again. This is the reason for the ‘lost keys’ phenomenon, if you have been out drinking and you lose your keys, and are unable to find it the next morning, chances are you will find them again next time you are drunk.

    This is because memory encodes differently in different states of consciousness, and therefore the context you are in largely determines how and where the memory will be placed. Retrieval cues are stimuli, states of mind, or thoughts that can be used to facilitate retrieval of information.
  • The spacing effect – the superiority of memory for information rehearsed over longer intervals – demonstrates that spacing study sessions over longer intervals tends to double long term retention of information.
  • The ability to retrieve information from LTM also depends on the modes used to encode it. In general, the more ways a memory can be encoded, the greater likelihood that it will be accessible for later retrieval. So maybe next time you see your passport you should smell it or put it up to your ear and listen to it!

Networks of Association

As mentioned earlier, the most powerful method for retaining memory is to create many associations between new information and old. Associations are crucial to remembering because the pieces of information stored in memory form networks of association; clusters of interconnected information. For example, most people would associate the word dog with fetch or bark. A slightly less strong association between dog would be cat, as they are both household pets.

The word dog might also be linked to more personal memories, such as fond memories of your dog, or a time when you were bitten by a dog in childhood. Each piece of information along a network is called a node. Nodes may be thoughts, images, concepts, books, propositions, smells, tastes, films, memories, songs, emotions or any other piece of information.

One node might link to and branch off into hundreds of other nodes, which create a strong semantic web of memory. This is how conversations move forwards, as you are listening to someone speak, certain words trigger nodes in your semantic memory, therefore bringing new information into your working memory, which progresses the conversation from one topic to the next. This triggering of nearby nodes is known as the spreading activation theory, and is quite humorously demonstrated in the following South Park clip. [youtube=] You can also check out the music map website, input a musician or a band and it will generate a semantic map of artists who are similar; the closer their nodes are to the initial node, the more related their music is.

Schemas – 

Schemas are patterns of thought, or organised knowledge structures, that render the environment relatively predictable. Basically they are a visual archetype or symbol of something in your mind’s eye. They are also generally shared by a collective society, for example, if I were to tell you I was a clown for a living in conversation, you would immediately bring to mind an image of a typical circus clown with white face makeup and a red nose – this is a schema. Situations can also be schemas, for example when students walk into a classroom on the first day of school and a person resembling a teacher begins to lecture, they listen and take notes in a routine fashion.

Students are not surprised that a stranger has walked in, taken control of the class and started talking, because they already have a schema for what occurs in a classroom. The following clip from Catch Me if You Can demonstrates this quite well, when Leonardo DiCaprio’s character pretends to be the substitute teacher on the first day of school. [youtube=]

Remembering and Forgetting

Memory is something that humans came to develop through natural selection, and while it is certainly extremely useful, it also has it’s flaws. Daniel Schacter (1999) who has spent his entire life studying memory, has outlined the ‘seven sins’ of memory:

  1. Transience – the fact that memories fade.
  2. Absent-mindedness – the failure to remember something when attention is elsewhere.
  3. Misattribution – misremembering the source of a memory.
  4. Suggestibility – thinking we remember an event that someone actually implanted in our minds.
  5. Bias – distortions in the way we recall events that often tell the story in a way we would rather remember it.
  6. Persistence – memories we try to get rid of but can’t.
  7. Forgetting – the inability to remember.

Despite these flaws or weaknesses, memory is still a very powerful tool. Studies on long-term memory have found that information that has been consolidated through spacing over long intervals will last a lifetime, even if the information is not used for half a century. So even if you stopped speaking until the moment before you died, you would still remember how to produce your last words.

Most times remembering something is like consulting an artist’s sketch rather than a photograph, as we are highly susceptible to altering or changing a memory either consciously or subconsciously. However, there are such memories that are highly resistant to forgetting and other forms of memory decay. These are called flashbulb memories, which are vivid, photographic memories of highly exciting or emotionally arousing events in one’s life.

Why Do People Forget?

  • Decay theory explains forgetting as a result of a fading memory trace. Much like a trail in a forest will overgrow with vegetation unless it is regularly walked on.
  • Interference theory suggests that similar memories can intrude on each other and cause overlap. Just like a fork in a forest path can confuse someone as to which direction leads back to their campsite. Cognitive psychologists distinguish between two types of interference, proactive interference and retroactive.
    1. Proactive interference refers to the interference of previously stored memories with the retrieval of new information, as when a person calls a person calls a new romantic partner by the name of an old one.
    2. Retroactive interference is when new information interferes with retrieval of old information, for example when you have difficulty remembering phone numbers of houses you used to live in because you have learnt your new home number.
  • Motivated forgetting is when forgetting is done for a reason. This can be implicit, like when you forget where you parked your car yesterday so you can remember where you parked today, or it can be explicit such as when you try to forget an unpleasant memory.
  • Repression is when someone buries a traumatic memory in their unconscious mind so that it can no longer spring up in their waking state. The cost of repressing a memory often results in negative emotions and mental illnesses coming up in daily life instead, such as anxiety or depression.
  • False memories are completely fabricated events made up by people, often they are created without the intention of being false, as the person usually believes the event to be true.

We have seen how distortion of memories can occur in the average person, however, specific kinds of distortion can also occur in the brains of people who have suffered illness or accidents, these are called disordered memories. The two main types of disordered memories are anterograde amnesia and retrograde amnesia.

Anterograde amnesia involves the inability to retain new memories, usually from after the accident that caused the amnesia. Retrograde amnesia involves the inability to remember old memories from a period before the accident that caused the amnesia.

Check Out Part 2 of Psychology 101 – Learning! Other guides in the Psychology 101 series: