Study of memory in psychology

Study of Memory in Psychology

Dr. Magda FahmyProfessor of PsychiatrySuez Canal University

[email protected]

• “Memory is the process of maintaining information over time.” (Matlin, 2005)

• “Memory is the means by which we draw on our past experiences in order to use this information in the present.’ (Sternberg, 1999)

• Memory is the term given to the structures and processes involved in the storage and subsequent retrieval of information.

• Memory is involved in processing vast amounts of information. This information takes many different forms, e.g. images, sounds or meaning.

1. Encoding and Memory

• When information comes into our memory system (from sensory input), it needs to be changed into a form that the system can cope with, so that it can be stored. (Think of this as similar to changing your money into a different currency when you travel from one country to another).

• For example, a word which is seen (on the whiteboard) may be stored if it is changed (encoded) into a sound or a meaning (i.e. semantic processing).


• There are three main ways in which information can be encoded (changed):

• 1. Visual (picture)

• 2. Acoustic (sound)

• 3. Semantic (meaning)


• For example, how do you remember a telephone number you have looked up in the phone book? If you can see it then you are using visual coding, but if you are repeating it to yourself you are using acoustic coding (by sound).


• Evidence suggests that this is the principle coding system in short term memory (STM) is acoustic coding.

• When a person is presented with a list of numbers and letters, they will try to hold them in STM by rehearsing them (verbally).

• Rehearsal is a verbal process regardless of whether the list of items is presented acoustically (someone reads them out), or visually (on a sheet of paper).


• The principle encoding system in long term memory (LTM) appears to be semantic coding (by meaning). However, information in LTM can also be coded both visually and acoustically.

2. Storage and Memory

• This concerns the nature of memory stores, i.e. where the information is stored, how long the memory lasts for (duration), how much can be stored at any time (capacity) and what kind of information is held.

• The way we store information affects the way we retrieve it.

• There has been a significant amount of research regarding the differences between Short Term Memory (STM ) and Long Term Memory (LTM)

http://www.simplypsychology.org/short-term-memory.html

http://www.simplypsychology.org/long-term-memory.html


• Most adults can store between 5 and 9 items in their short-term memory.

• Miller put this idea forward and he called it the magic number 7.

• He though that short-term memory capacity was 7 (plus or minus 2) items because it only had a certain number of “slots” in which items could be stored.


• Short-term memory: Miller didn’t specify the amount of information that can be held in each slot. Indeed, if we can “chunk” information together we can store a lot more information in our short-term memory.

• In contrast the capacity of LTM is thought to be unlimited.

• Information can only be stored for a brief duration in STM (0-30 seconds), but LTM can last a lifetime.

3. Retrieval and Memory

• This refers to getting information out storage. If we can’t remember something, it may be because we are unable to retrieve it.

• When we are asked to retrieve something from memory, the differences between STM and LTM become very clear.


• STM is stored and retrieved sequentially. For example, if a group of participants are given a list of words to remember, and then asked to recall the fourth word on the list, participants go through the list in the order they heard it in order to retrieve the information.

• LTM is stored and retrieved by association. This is why you can remember what you went upstairs for if you go back to the room where you first thought about it.


• Organizing information can help aid retrieval. You can organize information in sequences (such as alphabetically, by size or by time).

• Imagine a patient being discharged form hospital whose treatment involved taking various pills at various times, changing their dressing and doing exercises. If the doctor gives these instructions in the order which they must be carried out throughout the day (i.e. in sequence of time), this will help the patient remember them.

The multi store model

• The multi store model (Atkinson and Shiffrin, 1968) is a classic model of memory. It is sometimes called the modal model or the dual process model.

• Atkinson and Shiffrin (1968) suggest that memory is made up of a series of stores.

The multi store model (Atkinson and Shiffrin 1968)

• The multi store model (Atkinson and Shiffrin 1968) describes memory in terms of information flowing through a system.

• Information is detected by the sense organs and enters the sensory memory.

• If attended to this information enters the short term memory.

• Information from the STM is transferred to the long-term memory only if that information is rehearsed.

• If rehearsal does not occur, then information is forgotten, lost from short term memory through the processes of displacement or decay.

Sensory Memory

• Duration: ¼ to ½ second

• Capacity: all sensory experience (v. larger capacity)

• Encoding: sense specific (e.g. different stores for each sense)

Short term memory

• Duration: 15 and 30 seconds

• Capacity: 7 +/- 2 items

• Encoding: mainly auditory

Long term memory

• Duration: Unlimited

• Capacity: Unlimited

• Encoding: Mainly Semantic (but can be visual and auditory)

Short Term Memoryby Saul McLeod published 2009

Short term memory has three key aspects: 1. limited capacity (only about 7 items can be stored

at a time)

2. limited duration (storage is very fragile and information can be lost with distraction or passage of time)

3. encoding (primarily acoustic, even translating visual information into sounds).

http://www.simplypsychology.org/saul-mcleod.html

Short Term Memory

• There are two ways in which capacity is tested, one being span, the other being recency effect.

• Miller’s (1956) Magic number 7 (plus or minus two) provides evidence for the capacity of short term memory.

• Most adults can store between 5 and 9 items in their short-term memory. This idea was put forward by Miller (1956) and he called it the magic number 7. He though that short term memory could hold 7 (plus or minus 2 items) because it only had a certain number of “slots” in which items could be stored.

Short Term Memory

• The duration of short term memory seems to be between 15 and 30 seconds, according to Atkinson and Shiffrin (1971).

• Items can be kept in short term memory by repeating them verbally (acoustic encoding), a process known as rehearsal.

http://www.simplypsychology.org/multi-store.html


Short Term Memory

• Using a technique called the Brown-Peterson technique which prevents the possibility of retrieval by having participants count backwards in 3s, Peterson and Peterson 1959 showed that the longer the delay, the less information is recalled.

• The rapid loss of information from memory when rehearsal is prevented is taken as an indication of short term memory having a limited duration.

http://www.simplypsychology.org/peterson-peterson.html

Why We Remember What We Remember

• Short Term Memory. There are typically six reasons why information is stored in our short term memory.

• 1. primacy effect information that occurs first is typically remembered better than information occurring later. When given a list of words or numbers, the first word or number is usually remembered due to rehearsing this more than other information.

• 2. recency effect - often the last bit of information is remembered better because not as much time has past; time which results in forgetting.

http://allpsych.com/dictionary/p.html

http://allpsych.com/dictionary/r.html



• 3. distinctiveness - if something stands out from information around it, it is often remembered better. Any distinctive information is easier to remember than that which is similar, usual, or mundane.

• 4. frequency effect - rehearsal, as stated in the first example, results in better memory. Remember trying to memorize a formula for your math class. The more you went over it, the better you knew it.

• 5. associations - when we associate or attach information to other information it becomes easier to remember. Many of us use this strategy in our professions and everyday life in the form of acronyms إختصارات .

• 6. reconstruction - sometimes we actually fill in the blanks in our memory. In other words, when trying to get a complete picture in our minds, we will make up the missing parts, often without any realization that this is occurring.

• Baddeley and Hitch (1974) have developed an alternative model of short-term memory which they call working memory.

http://www.simplypsychology.org/working%20memory.html


• Environmental input sensory memory(Attention) working memory

Rehearsal Retrieval

long term memory

working memory

• Working memory is STM. Instead of all information going into one single store, there are different systems for different types of information.

• Working memory consists of a central executive which controls and co-ordinates the operation of two subsystems:

1- phonological loop and2- visuo-spatial sketchpad.

working memory

Central Executive: Drives the whole system (e.g. the boss of working memory) and allocates data to the subsystems (VSS & PL). It also deals with cognitive tasks such as mental arithmetic and problem solving.

• A. Visuo-Spatial Sketch Pad (inner eye): Stores and processes information in a visual or spatial form. The VSS is used for navigation.

• B. The phonological loop is the part of working memory that deals with spoken and written material. It can be used to remember a phone number. It consists of two parts

1. Phonological Store (inner ear) – Linked to speech perception Holds information in speech-based form (i.e. spoken words) for 1-2 seconds.

2. Articulatory control process (inner voice) – Linked to speech production. Used to rehearse and store verbal information from the phonological store.

• The phonological loop is assumed to be responsible for the manipulation of speech based information.

• The visuo-spatial sketchpad is assumed to be responsible for manipulating visual images.

• The model proposes that every component of working memory has a limited capacity, and also that the components are relatively independent of each other.

Empirical Evidence for the Working Memory Model

• What evidence is there that working memory exists, that it is made up of a number of parts, that it performs a number of different tasks?

• The working memory model makes the following two predictions:

• 1. If two tasks make use of the same component (of working memory), they cannot be performed successfully together.

• 2. If two tasks make use of different components, it should be possible to perform them as well as together as separately.

Key Study: Baddeley and Hitch (1976) • Aim: To investigate if participants can use different parts

of working memory at the same time.

• Method: Conducted an experiment in which participants were asked to perform two tasks at the same time (dual task technique) - a digit span task which required them to repeat a list of numbers, and a verbal reasoning task which required them to answer true or false to various questions (e.g. B is followed by A?).

• Results: As the number of digits increased in the digit span tasks, participants took longer to answer the reasoning questions, but not much longer - only fractions of a second. And, they didn't make any more errors in the verbal reasoning tasks as the number of digits increased.

• Conclusion: The verbal reasoning task made use of the central executive and the digit span task made use of the phonological loop.

The Central Executive

• The central executive is the most important component of the model, although little is known about how it functions.

• It is responsible for monitoring and coordinating the operation of the slave systems (i.e. visuo-spatial sketch pad and phonological loop) and relates them to long term memory (LTM).

• The central executive decides which information is attended to and which parts of the working memory to send that information to be dealt with.



• The central executive decides what working memory pays attention to.

• For example, two activities sometimes come into conflict such as driving a car and talking. Rather than hitting a cyclist who is wobbling all over the road, it is preferable to stop talking and concentrate on driving. The central executive directs attention and gives priority to particular activities.


• Baddeley suggests that the central executive acts more like a system which controls attentional processes rather than as a memory store.

• This is unlike the phonological loop and the visuo-spatial sketchpad, which are specialized storage systems.

• The central executive enables the working memory system to selectively attend to some stimuli and ignore others.


• Baddeley (1986, 1999) uses the metaphor of a company boss to describe the way in which the central executive operates.

• The company boss makes decisions about which issues deserve attention and which should be ignored. They also select strategies for dealing with problems, but like any person in the company, the boss can only do a limited number of things at the same time.


• The boss of a company will collect information from a number of different sources. If we continue applying this metaphor, then we can see the central executive in working memory integrating (i.e. combining) information from two assistants (the phonological loop and the visuo-spatial sketchpad) and also drawing on information held in a large database (long-term memory).

The phonological loop


• The phonological loop is the part of working memory that deals with spoken and written material. It consists of two parts.

• 1. The phonological store (linked to speech perception) acts as an inner ear and holds information in speech-based form (i.e. spoken words) for 1-2 seconds. Spoken words enter the store directly. Written words must first be converted into an articulatory (spoken) code before they can enter the phonological store.


• 2. The articulatory control process (linked to speech production) acts like an inner voice rehearsing information from the phonological store. It circulates information round and round like a tape loop. This is how we remember a telephone number we have just heard. As long as we keep repeating it, we can retain the information in working memory.


• The articulatory control process also converts written material into an articulatory code and transfers it to the phonological store.

The Visuo-Spatial Sketchpad

• The visuo-spatial sketchpad (inner eye) deals with visual and spatial information.

• Visual information refers to what things look like. It is likely that the visuo-spatial sketchpad plays an important role in helping us keep track of where we are in relation to other objects as we move through our environment (Baddeley, 1997).


• As we move around, our position in relation to objects is constantly changing and it is important that we can update this information.

• For example, being aware of where we are in relation to desks, chairs and tables when we are walking around a classroom means that we don't bump into things too often!


• The sketchpad also displays and manipulates visual and spatial information held in long-term memory.

• For example, the spatial layout of your house is held in LTM. Try answering this question: How many windows are there in the front of your house? You probably find yourself picturing the front of your house and counting the windows. An image has been retrieved from LTM and pictured on the sketchpad.


• Evidence suggests that working memory uses two different systems for dealing with visual and verbal information.

• A visual processing task and a verbal processing task can be performed at the same time. It is more difficult to perform two visual tasks at the same time because they interfere with each other and performance is reduced. The same applies to performing two verbal tasks at the same time.


• This supports the view that the phonological loop and the sketchpad are separate systems within working memory.

Evaluation of Working Memory

• Researchers today generally agree that short-term memory is made up of a number of components or subsystems. The working memory model has replaced the idea of a unitary (one part) STM as suggested by the multistore model.


• The working memory model explains a lot more than the multistore model.

• It makes sense of a range of tasks - verbal reasoning, comprehension, reading, problem solving and visual and spatial processing. And the model is supported by considerable experimental evidence.


The working memory applies to real life tasks:- Reading (phonological loop)- Problem solving (central executive) - Navigation (visual and spatial processing)


• The KF Case Study supports the Working Memory Model. KF suffered brain damage from a motorcycle accident that damaged his short-term memory. KF's impairment was mainly for verbal information - his memory for visual information was largely unaffected. This shows that there are separate STM components for visual information (VSS) and verbal information (phonological loop).


• Working memory is supported by dual task studies (Baddeley and Hitch, 1976).

• The working memory model does not over emphasize the importance of rehearsal for STM retention, in contrast to the multi-store model.

Weaknesses of working memory model

• Lieberman criticizes the working memory model as the visuo-spatial sketchpad (VSS) implies that all spatial information was first visual (they are linked). However, Lieberman points out that blind people have excellent spatial awareness although they have never had any visual information. Lieberman argues that the VSS should be separated into two different components: one for visual information and one for spatial.

Weaknesses of working memory model

• There is little direct evidence for how the central executive works and what it does. The capacity of the central executive has never been measured.

• Working memory only involves STM so it is not a comprehensive model of memory (as it does not include SM or LTM).

• The working memory model does not explain changes in processing ability that occur as the result of practice or time.

Long Term Memoryby Saul McLeod published 2010

• Theoretically, the capacity of long term memory could be unlimited, the main constraint on recall being accessibility rather than availability.

• Duration might be a few minutes or a lifetime. • Suggested encoding modes are semantic

(meaning) and visual (pictorial) in the main but can be acoustic also.


Long Term Memory

• Bahrick et al (1975) investigated what they called very long term memory (VLTM). Nearly 400 participants aged 17 – 74 were tested. There were various tests including:

1. A free recall test, where participants tried to remember names of people in a graduate class.

2. A photo recognition test, consisting of 50 pictures.

3. A name recognition test for ex-school friends.

Long Term Memory

• Participants who were tested within 15 years of graduation were about 90% accurate in identifying names and faces. After 48 years they were accurate 80% for verbal and 70% visual.

• Free recall was worse. After 15 years it was 60% and after 48 years it was 30% accurate.

Long Term Memory

• One of the earliest and most influential distinctions was proposed by Tulving (1972). He proposed a distinction between episodic, semantic and procedural memory.

Long Term Memory

• Procedural memory is a part of the long-term memory is responsible for knowing how to do things, i.e. memory of motor skills.

• It does not involve conscious (i.e. it’s unconscious - automatic) thought is not declarative.

• For example, procedural memory would involve knowledge of how to ride a bicycle.

Long Term Memory

• Semantic memory is a part of the long-term memory responsible for storing information about the world. This includes knowledge about the meaning of words, as well as general knowledge. For example, London is the capital of England. It involves conscious thought and is declarative.

Long Term Memory

• Episodic memory is a part of the long-term memory responsible for storing information about events (i.e. episodes) that we have experienced in out lives. It involves conscious thought and is declarative. An example would be a memory of our 1st day at school.

Long Term Memory

• Cohen and Squire (1980) drew a distinction between declarative knowledge and procedural knowledge.

• Procedural knowledge involves “knowing how” to do things. It included skills, such as “knowing how” to playing the piano, ride a bike; tie your shoes and other motor skills. It does not involve conscious (i.e. automatic) thought. For example, we brush our teeth with little or no awareness of the skills involved.

Long Term Memory

• Declarative knowledge involves “knowing that”, for example London is the capital of England, zebras are animals, your mums birthday etc. Recalling information from declarative memory involves some degree of conscious effort – information is consciously brought to mind and “declared”.

Long Term Memory

• The knowledge that we hold in semantic and episodic memories focuses on “knowing that” something is the case (i.e. declarative).

• For example, we might have a semantic memory for knowing that Paris is the capital of France, and we might have an episodic memory for knowing that we caught the bus to college today.

Long Term Memory

• Evidence for the distinction between declarative and procedural memory has come from research on patients with amnesia.

• Typically, amnesic patients have great difficulty in retaining episodic and semantic information following the onset of amnesia. Their memory for events and knowledge acquired before the onset of the condition tends to remain intact, but they can’t store new episodic or semantic memories. In other words, it appears that their ability to retain declarative information is impaired.

Long Term Memory

• However, their procedural memory appears to be largely unaffected. They can recall skills they have already learned (e.g. riding a bike) and acquire new skills (e.g. learning to drive).

• categorize memory as being explicit, which is defined as that involved in the conscious recall of information about people, places, and things, or

• implicit, which is characterized by the nonconscious recall of tasks such as motor skills.

• Explicit memory depends on the integrity of temporal lobe and diencephalic structures such as the hippocampus, subiculum, and entorhinal cortex.

• Implicit memory includes simple associative forms of memory, such as classical conditioning, and nonassociative forms, such as habituation, and relies on the integrity of the cerebellum and basal ganglia (582).

http://physrev.physiology.org/content/84/1/87.long

Levels of Processingby Saul McLeod published 2007

• The levels of processing model of memory (Craik and Lockhart, 1972) was put forward partly as a result of the criticism leveled at the multi-store model.

• Instead of concentrating on the stores/structures involved (i.e. short term memory & long term memory), this theory concentrates on the processes involved in memory.





Levels of Processing

• Unlike the multi-store model it is a non-structured approach. The basic idea is that memory is really just what happens as a result of processing information.

• Psychologists Craik and Lockhart propose that memory is just a by-product of the depth of processing of information and there is no clear distinction between short term memory and long term memory.

Levels of Processing

• Depth is defined as "the meaningfulness extracted from the stimulus rather than in terms of the number of analyses performed upon it.”

We can process information in 3 ways:

• Shallow Processing• - This takes two forms • 1. Structural processing (appearance) which is

when we encode only the physical qualities of something. E.g. the typeface of a word or how the letters look.

• 2. Phonemic processing – which is when we encode its sound.

• Shallow processing only involves maintenance rehearsal (repetition to help us hold something in the STM) and leads to fairly short-term retention of information. This is the only type of rehearsal to take place within the multi-store model.

• Deep Processing• - This involves • 3. Semantic processing, which happens when

we encode the meaning of a word and relate it to similar words with similar meaning.

• Deep processing involves elaboration rehearsal which involves a more meaningful analysis (e.g. images, thinking, associations etc.) of information and leads to better recall. For example, giving words a meaning or linking them with previous knowledge.

Summary

• Levels of processing: The idea that the way information is encoded affects how well it is remembered. The deeper the level of processing, the easier the information is to recall.

Application of the Levels of Processing Model in Real Life

• This explanation of memory is useful in everyday life because it highlights the way in which elaboration, which requires deeper processing of information, can aid memory. Three examples of this are.

• • Reworking – putting information in your own words or talking about it with someone else.

• Method of loci – when trying to remember a list of items, linking each with a familiar place or route.

• Imagery – by creating an image of something you want to remember, you elaborate on it and encode it visually (i.e. a mind map).

• The above examples could all be used to revise psychology using semantic processing (e.g. explaining memory models to your mum, using mind maps etc.) and should result in deeper processing through using elaboration rehearsal. Consequently more information will be remembered (and recalled) and better exam results should be achieved.

• Further Information• Memory• Short Term Memory• Long Term Memory• Multi-Store Model• Levels of Processing Model• Working Memory Model • How does working memory work in the classroom? • Visual and Auditory Working Memory Capacity • Is Working Memory Still Working • Working Memory Model

http://www.simplypsychology.org/memory.html




http://www.simplypsychology.org/levelsofprocessing.html

http://www.simplypsychology.org/Working%20Memory.pdf

http://www.simplypsychology.org/working%20memory%20work%20in%20the%20classroom.pdf

http://www.simplypsychology.org/Visual%20and%20auditory.pdf

http://www.simplypsychology.org/Is%20Working%20Memory%20Still%20Working.pdf

http://www.simplypsychology.org/WM%20Lecture.ppt

Forgettingby Saul McLeod published 2008

• Why do we forget? There are two simple answers to this question.

First, the memory has disappeared - it is no longer available.

Second, the memory is still stored in the memory system but, for some reason, it cannot be retrieved.

• The first answer is more likely to be applied to forgetting in short term memory, the second to forgetting in long term memory.


Forgetting

• Forgetting information from short term memory (STM) can be explained using the theories of trace decay and displacement.

• Forgetting from long term memory (LTM) can be explained using the theories of interference and lack of consolidation.



Trace Decay Theory of Forgetting (STM)

• This theory relates to both short term memory and long term memory, and also relates to lack of availability.

• This theory suggests short term memory can only hold information for between 15 and 30 seconds unless it is rehearsed. After this time the information decays (fades away).

Trace Decay Theory

• This explanation of forgetting in short term memory assumes that memories leave a trace in the brain.

• A trace is some form of physical and/or chemical change in the nervous system.

• Trace decay theory states that forgetting occurs as a result of the automatic decay or fading of the memory trace.

• Trace decay theory focuses on time and the limited duration of short term memory.

Trace Decay Theory

• memory tends to get worse the longer the delay between learning and recall

• The longer the time, the more the memory trace decays and as a consequence more information is forgotten.

Trace Decay Theory

• in any real-life situation, the time between learning something and recalling it will be filled with all kinds of different events. This makes it very difficult to be sure that any forgetting which takes place is the result of decay rather than a consequence of the intervening events.

Trace Decay Theory

• Support for the idea that forgetting from short-term memory might be the result of decay over time came from research carried out by Brown (1958) in the United Kingdom, and Peterson and Peterson (1959) in the United States.

• The technique they developed has become known as the Brown-Peterson task.

Key Study: Peterson and Peterson (1959) – Duration of STM

• Aim: They wanted to test their hypothesis that information was held in the STM for only around 20 seconds, after that it disappears if rehearsal is prevented. Therefore aiming to prove that the duration of the STM is only around 20 seconds. Also, to investigate if information is lost from STM through decay.

• Method: Participants were presented with sets of trigrams (nonsense syllables in sets of three, e.g. BCM) which they were then asked to recall in order after a delay of 3, 6, 9, 12, 15 and 18 seconds. An experimental method was used: The IV was the time delay, and the DV was the number of trigrams recalled.

• Participants were given an interference task of counting backwards in threes from a random three-digit number to prevent rehearsal (known as the Brown-Peterson technique).

• Recall had to be 100% accurate and in the correct order in order for it to count as correctly recalled.

• Results: The percentage recall was:

• After 3 seconds = 80%

• After 6 seconds = 50%

• After 18 seconds = less than 10%

• Recall decreases steadily between 3 and 18 seconds suggesting that the duration of the STM is not much more than 18 seconds.

• Conclusion: The memory trace in the STM has just about disappeared after 18 seconds. Information held in the STM is quickly lost without rehearsal.

• This supports the hypothesis that the duration of the STM is limited to approximately 20 seconds.

• They also concluded that this is evidence that the STM is distinct from the LTM as the LTM has a much longer duration (i.e. the results also support the multi-store model).

Trace Decay Theory

• Peterson and Peterson (1959) explained this rapid loss in terms of trace decay. The memory trace fades over time until it disappears completely. At this point, information is forgotten.

Displacement from Short Term Memory (STM)

• Displacement seeks to explain forgetting in short term memory, and suggests it’s due to a lack of availability.

• The short-term memory store in Atkinson & Shiffrin's (1968) model of memory was assumed to have certain characteristics, including a limited capacity, and if information was not rehearsed, it would be forgotten.


• Displacement theory provides a very simple explanation of forgetting. Because of its limited capacity, suggested by Miller to be 7+/- 2 items, STM can only hold small amounts of information.

• When STM is 'full', new information displaces or 'pushes out’ old information and takes its place.

• The old information which is displaced is forgotten in STM.


• It was also assumed that the information that had been in the short-term store for the longest was the first to be displaced by new information, similar to the way in which boxes might fail off the end of a conveyor belt - as new boxes are put on one end, the boxes which have been on the conveyor belt the longest drop off the end.


• Support for the view that displacement was responsible for the loss of information from short-term memory came from studies using the 'free-recall' method.

• A typical study would use the following procedure: participants listen to a list of words read out a steady rate, usually two seconds per word; they are then asked to recall as many of words as possible. They are free to recall the words in any order, hence the term 'free recall'.


• The findings from studies using free recall are fairly reliable and they produce similar results on each occasion. If you take each item in the list and calculate the probability of participants recalling it (by averaging recall of the word over all participants) and plot this against the item's position in the list, it results in the serial position curve (Figure 1)

Simplified representation of the serial position curve for immediate recall


• Good recall of items at the beginning of the list is referred to as the primacy effect and good recall if items at the end of the list are referred to as the recency effect.

• T he displacement theory of forgetting from short-term memory can explain the recency effect quite easily. The last few words that were presented in the list have not yet been displaced from short-term memory and so are available for recall.


• The primacy effect can be explained using Atkinson & Shiffrin's (1968) multi-store model which proposes that information is transferred into long-term memory by means of rehearsal.

• The first words in the list are rehearsed more frequently because at the time they are presented they do not have to compete with other words for the limited capacity of the short-term store.


• This means that words early in the list are more likely to be transferred to long-term memory. So the primacy effect reflects items that are available for recall from long-term memory.

• However, words in the middle of the list used to be in short term memory until they were pushed out - or displaced by the words at the end of the list.

Interference (LTM)

• Interference theory states that forgetting occurs because memories interfere with and disrupt one another, in other words forgetting occurs because of interference from other memories (Baddeley, 1999).

Interference (LTM)

• 1. Proactive interference (pro=forward) occurs when a person cannot remember new information because it has been confused with old information.

• 2. Retroactive interference (retro=backward) occurs when you cannot remember old information because new information has interfered with it.

Interference (LTM)

• Previous learning can sometimes interfere with new learning (e.g. difficulties we have with foreign currency when travelling abroad).

• Also new learning can sometimes cause confusion with previous learning. (Starting French may affect our memory of previously learned Spanish vocabulary).

Interference

• Interference is thought to be more likely to occur where the memories are similar, for example: confusing old and new telephone numbers.

• Students who study similar subjects at the same time often experience interference. Starting French may affect our memory of previously learned Spanish vocabulary.

Interference (LTM)

• In the short term memory interference can occur in the form of distractions so that we don’t get the chance to process the information properly in the first place. (e.g. someone using a loud drill just outside the door of the classroom.)

Lack of consolidation (LTM)

• The previous accounts of forgetting have focused primarily on psychological evidence, but memory also relies on biological processes. For example, we can define a memory trace as:

• 'some permanent alteration of the brain substrate in order to represent some aspect of a past experience'.


• When we take in new information, a certain amount of time is necessary for changes to the nervous system to take place – the consolidation process – so that it is properly recorded.

• During this period information is moved from short term memory to the more permanent long term memory.


• The brain consists of a vast number of cells called neurons, connected to each other by synapses. Synapses enable chemicals to be passed from one neuron to another. These chemicals, called neurotransmitters, can either inhibit or stimulate the performance of neurons.


• So if you can imagine a network of neurons all connected via synapses, there will be a pattern of stimulation and inhibition. It has been suggested that this pattern of inhibition and stimulation can be used as a basis for storing information.

• This process of modifying neurons in order form new permanent memories is referred to as consolidation (Parkin, 1993).


• There is evidence that the consolidation process is impaired if there is damage to the hippocampus.

• In 1953, HM had brain surgery to treat his epilepsy, which had become extremely severe. The surgery removed parts of his brain and destroyed the hippocampus, and although it relieved his epilepsy, it left him with a range of memory problems.

• Although his STM functioned well, he was unable to process information into LTM.


• The main problem experienced by HM is his inability to remember and learn new things. This inability to form new memories is referred to as anterograde amnesia.

• However, of interest in our understanding of the duration of the process of consolidation is HM's memory for events before his surgery.


• In general, his memory for events before the surgery remains intact, but he does have some memory loss for events which occurred in the two years leading up to surgery.


• Pinel (1993) suggests that this challenges Hebb's (1949) idea that the process of consolidation takes approximately 30 minutes. The fact that HM's memory is disrupted for the two-year period leading up to the surgery indicates that the process of consolidation continues for a number of years.

• Finally, aging can also impair our ability to consolidate information.

Retrieval failure theory (LTM)

• Retrieval failure is where the information is in long term memory, but cannot be accessed.

• Such information is said to be available (i.e. it is still stored) but not accessible (i.e. it cannot be retrieved).

• It cannot be accessed because the retrieval cues are not present.


• When we store a new memory we also store information about the situation and these are known as retrieval cues. When we come into the same situation again, these retrieval cues can trigger the memory of the situation.

Retrieval cues can be:• External / Context - in the environment, e.g. smell, place

etc.

• Internal / State- inside of us, e.g. physical, emotional, mood, drunk etc.


• Tulving (1974) argued that information would be more readily retrieved if the cues present when the information was encoded were also present when its retrieval is required.

• For example, if you proposed to your partner when a certain song was playing on the radio, you will be more likely to remember the details of the proposal when you hear the same song again. The song is a retrieval cue - it was present when the information was encoded and retrieved.


• Tulving suggested that information about the physical surroundings (external context) and about the physical or psychological state of the learner (internal context) is stored at the same time as information is learned.

• Reinstating the state or context makes recall easier by providing relevant information, while retrieval failure occurs when appropriate cues are not present. For example, when we are in a different context (i.e. situation) or state.

Context (external) Dependent Forgetting

• Retrieval cues may be based on context-the setting or situation in which information is encoded and retrieved.

• Evidence indicates that retrieval is more likely when the context at encoding matches the context at retrieval.

• Examples include a particular room, driving along a motorway, a certain group of people, a rainy day and so on.


• You may have experienced the effect of context on memory if you have ever visited a place where you once lived (or an old school).

• Often such as visit helps people recall lots of experiences about the time they spent there which they did not realize were stored in their memory.

State (internal) dependent cues

• The basic idea behind state-dependent retrieval is that memory will be best when a person's physical or psychological state is similar at encoding and retrieval.

• For example, if someone tells you a joke on Saturday night after a few drinks, you'll be more likely to remember it when you're in a similar state - at a later date after a few more drinks. Stone cold sober on Monday morning, you'll be more likely to forget the joke.


• State Retrieval clues may be based on state-the physical or psychological state of the person when information is encoded and retrieved.

• For example, a person may be alert, tired, happy, sad, drunk or sober when the information was encoded. They will be more likely to retrieve the information when they are in a similar state.


• People tend to remember material better when there is a match between their mood at learning and at retrieval.

• The effects are stronger when the participants are in a positive mood than a negative mood.

• They are also greater when people try to remember events having personal relevance.

Measures of retention

Measures of retention. Memories may be retrieved in three ways.

• recall: remembering of previously learned information – free recall: recall of items in any order – serial recall: recall of items in the order in which they were learned – paired associate recall: recall of a second item based on a cue

supplied by a first item • recognition: identification of previously learned information

(as, for example from a number of answer choices in a multiple-choice test)

• reconstruction: rebuilding of a scenario from certain remembered details

Amnesia

• is the inability to remember events from the past because of a psychological trauma ( psychogenic amnesia) or a physiological trauma ( organic amnesia), such as brain damage resulting from a blow to the head. The memory loss is usually limited to a specific period.

• Retrograde amnesia is the inability to remember happenings that preceded the traumatic event producing the amnesia.

• Anterograde amnesia is the inability to remember happenings that occur after a traumatic event.

Amnesia

• People sometimes forget things because they find them too unpleasant to think about.

• Such an occurrence is called motivated forgetting.

• Sigmund Freud attributed many memory failures, particularly involving painful childhood experiences, to repression (the process of keeping disturbing thoughts or feelings relegated to the unconscious).

Amnesia

• The repressed material can sometimes be recalled through free association or hypnosis.

• The recovery of supposedly repressed memories, such as those of childhood sexual abuse, is controversial.

Biological Substrates in Memory

• Although much information exists on the connection between memory and biology, it is far from complete.

• At the neuron level, a deficiency of the neurotransmitter acetylcholine is a factor in the dementia known as Alzheimer's disease (administration of the neurotransmitter has slowed the disease's progress but not prevented it).

• Reduced levels of the neurotransmitter glutamate have also been associated with the disorder.

• Serotonin, another neurotransmitter, is also thought to be important in memory functioning.

• Eric Kandel and James Schwartz, in a study of sea snails, found that serotonin is released as they learn.

• At the structural level, damage to the hippocampus, part of the limbic system, has been associated with memory difficulties.

Study of memory in psychology

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