Psychology: Memory

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Introduction to Memory

A normally functioning memory system must be capable of the following:

  • registering/acquiring (encoding) information
  • storing(retaining) the information over time
  • retrieving (recovering) the information when required

There are 3 types of memory:

  • Sensory memory
  • Long term memory
  • Short term memory
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Sensory memory

  • Storage system that holds information in a relatively unprocessed form
  • holds the information for fractions of a second afer the physical stimulus is no longer available
  • Baddeley suggested that one function of his storage is to allow information from successive eye fixations to last enough time to be integrated into our memory 
  • this therefore gives continuity to our visual environment
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Short-term memory


  • system for storing information for brief periods of time
  • some researchers see STM as a temporary storage depot for incoming information
  • Others such as Baddeley use the term "working memory" to show that it has dynamic and flexible aspects

Nature of STM:

  • Capacity: the amount of infortmation that can be stored at any one time
  • Duration: the length of time that information can be held in STM
  • Encoding: the way that sensory input is represented in STM
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Capacity of STM


  • STM has a limited capacity
  • we can only hold a small number of items at any one time
  • immediate digit span is an indicator of the capacity of memory
  • Miller (1956) found that most people have a digit span of "seven plus or minus two"
  • this has been named "Miller's magic number seven"
  • Miller also claimed this finding is good for lists of digits, words or larger "chunks" of information
  • "Chunking" occurs when individual letters or numbers are combined into a larger meaningful unit
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Factors affecting STM capacity

  • Influence of LTM: difficult to exclude this influence, sometimes info stored in LTM is helping to increase STM capacity
  • Reading aloud: if participants read aloud before attempting recallm performance is better than reading without subvocal repetition
  • Rhythmic grouping: performance improves if numbers are rhythmically grouped together which is why we divide phone numbers into rhythmic clusters rather than reciting the whole thing
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Duration of STM

  • Has a brief duration
  • used as a temporary store and anything we need to remember for longer needs to be transferred to LTM

Factors affecting the duration of STM:

  • Maintenance rehearsal: items disappear from STM only when rehearsal is prevented. New items can only take place if existing items move on or if items in LTM are forgotten
  • Deliberate intention to recall: Information can easily vanish if people do not make a conscious effort to retain it
  • Amount of information to be retained: the number of chunks to be remembered is an important factor rather than the number of individual items
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Encoding in STM

  • When information arrives at sensory stage it's still in it's original modality
  • Various ways we can encode stimulus inputs
  • Not possible to ask people what coding systems they're using because memory processes are often unconscious
  • Semantic, acoustic and visual representations can all by made in trying to remember the same item

Factors affecting encoding in STM:

  • Sound of words: Conrad (1964) suggested STM relies heavily on acoustic coding, others thought type of stimulus to be remembered might affect way it was encoded
  • Other ways of encoding: seems likely acoustic encoding is the preferred method of encoding in STM, several studies show other forms of representation are possible
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Long-term memory

  • Holds a vast quantity of information that can be stored for long periods of time
  • Information here is diverse and wide rangingg
  • Includes plans for the future and where our knowledge about skills and expertise is deposited
  • likely it isn't a single store but a number of different systems with different functions
  • Not a passive store of info but a dynamic one 
  • Much larger and more complex than STM
  • differs from STM in terms of capacity duration and encoding


  • not possible to quantify the capacity of LTM
  • most psychologists agree there is no upper limit and we're always capable of more learning
  • huge capacity of LTM requires organised structure

Duration: A lifetime

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Factors affecting duration of LTM

Childhood amnesia:

  • Very young children incapable of laing down well organised integrated memories so they're not available for later recall

How duration is measured:

  • People much better at remembering information from long ago if they are tested by recognition as opposed to free recall

Thorough learning:

  • seems people are more likely to hold information in permastore if they learnt it very well in the first place and continued to learn about related material in the interval
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Encoding in LTM

Some evidence that the meaning of the stimulus is often the main factor in encoding in LTM (i.e semantic)

Factors affecting encoding in LTM:

  • acoustic encoding: our ability to recognize sounds shows that we can store material in an acoustic form
  • Visual encoding: can easily bring to mind pictorial images of people or places that suggest some visual encoding in LTM
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Models of memory: Multi-store model (Atkinson and

  • Number of memory theorists proposed that the memory system is divided into 3 stores as previously described

Key features:

  • model arose from information being described as a flow of information through a system
  • system divided into set of stages and info passes through each stage in fixed sequence
  • capacity and duration limitations at each stage
  • transfer of info between stages may require re-coding
  • external stimuli from environment enter sensory memory where they can be registered for brief periods of time before decaying/passed on to STM
  • STM conains short amount of info that is in active use at the time, info usually acousitc at this stage
  • Memory traces in STM fragile and can be lost through decay/displacement unless rehearsed
  • Rehearsed material passed onto LTM where it can last a lifetime 
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Strengths/Weaknesses of multi-store model of memor


  • Distinguishes between short term and long term stores in terms of capacity, duration and encoding
  • There's evidence to support distinction between STM and LTM in cases of people with brain damage that has lead to memory impairment such as Clive Wearing
  • Further evidence for MSM comes from experiments into primary and recency effects


  • Although model has stimulated lots of research: it's too simplistic and inflexible to explain the entire memory system
  • doesn't take into account strategies and methods used to remember information
  • focuses too much on structure of the memory system rather than explaining the processes involved
  • suggests rehearsal is the only way of transferring info from STM > LTM
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Working memory model: Baddeley and Hitch (1974)


  • Replaces concept of unitary STM
  • proposes multi-component, flexible system concerned with processing short and long term information

Key features:

  • Central Executive: involved in problem solving and decision making
  • Main features include: 
  • - controls attention and has a major role in planning and synthesizing information
  • - flexible and can process info from any modality
  • - has a limited capacity
  • Phonological loop: stores limited number of speech based sounds for brief periods, consists of 2 components:
  • -Phonological store (inner ear) allows acoustically encoded items to be stored for brief period
  • -Articulatory control process (inner voice) allows subvocal repetition of items in phonological store
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Working memory model: Baddeley and Hitch (1974) co

Key features (continued):

Visuo-spatial scratch pad: stores visual and spatial information, can be thought of as the inner eye:

  • Responsible for setting up and maniupating mental images
  • has a limited capacity, limits of the 2 systems are independent 

Episodic buffer: proposed in 2000. Integrates and manipulates material in working memory. Features include:

  • limited capacity
  • capable of binding together information from different sources into chunks or episodes
  • one of its important functions is to integrate material from LTM to meet the requirements of working memory
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Strengths and Weaknesses of WMW


  • Has advantages over concept of STM outlined in MSM. Effectively explains ability to carry out mental arithmetic tasks for example by storing information briefly while actively processing it at the same time
  • Evidence supporting phonological loop
  • Evidence supporting visuo-spatial scratch pad


  • The comoponent we know least about is the most important
  • has a limited capacity but no one has been able to quantify it experimentally
  • Richardson (1984) argues there are problems in specifying the precise functioning of the central executive
  • he believes the terminology used is too vague to explain any kind of results
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Memory in everyday life: Factors affecting Eye Wit

  • Evidence in eye witness testimony usually takes the form of personal identification or a verbal account of what happened
  • such evidence is based on the memory of witnesses and unfortunately memory isn't always accurate
  • problems can occur at any point the in the memory process i.e during encoding, storage or retrieval
  • a number of different avenues have been pursued to find out why eyewitness testimony may be unreliable:
  • the role of anxiety
  • the role of schemas
  • the age of the witness
  • use of leading questions
  • consequences of the testimony
  • how witnesses are tested
  • the effects of misleading information
  • use of the cognitive interview
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The Role of Anxiety in EWT

  • Considerable importance is usually placed on evidence provided by eyewitnesses
  • Numerous studies have identified several problems with EWT, including anxiety experienced by witnesses at the time of the incident having an affect on the accuracy of memory

Yuille and Cushall (1986) provided evidence for accuracy of testimony regarding real-life events:

  • interviewed 13 witnesses to real-life shooting regarding owner of store and an armed thief
  • storeowner wounded but recovered
  • thief was shot dead
  • some witnesses were close to the incident, others were more distant
  • interviews showed witnesses gave impressive accounts months later
  • clsoest to event = most detail
  • misleading qs didn't affect accuracy
  • those who were most distressed at time of incident were most accurate 
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Further research into anxiety effects on EWT

Christianson and Hubinette (1993):

  • questioned 110 witnesses who had witnessed 22 genuine bank robberies
  • some witnesses were onlookers who happened to be in the bank
  • others were bank employees who had been directly threatened in the robberies
  • researchers found the following:
  • victims more accurate in recall and remembered more details about what robbers wore, behaviour and weapon used than the bystanders
  • superior recall continued to be evident after 15 month period
  • people better at remembering highly stressful events if they happen in real life rather than artificial surroundings
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Role of schemas in memory

Schemas: knowledge packages built up through experience of world and enamble us to make sense of familiar situations. Also aid the interpretation of new information

Schemas sometimes known as scripts if it includes knowledge of appropriate events or actions that should occur in a particular social setting

5 ways in which schemas might lead to reconstructive memory:

  • we tend to ignore aspects of a scene that do not fit in currently activated schema
  • can store central features of an event wihtout having to store the exact details
  • can make sense of what we have seen by filling in missing details 
  • distort memories for events to fit in with prioer expectations
  • may use schemas to provide basis for a correct guess
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Role of the age of the witness in EWT

  • Children are usually seen as unreliable witnesses and that their testimony should be treated as suspect
  • there are some times when a child may be the only witness to a crime
  • reliability of a child's witness testimony is important, although controversial
  • Factors affecting the accuracy of children's eyewitness testimony:
  • Encoding: Ceci and Bruck (1993) said one reason children may be inaccurate in providing EWT is their lack of appropriate schemas or scripts for the event witnessed
  • Storage: as time between encoding and retrieval increases, recall and recognition declines in both adults and children
  • Retrieval: children omit more than adults but relevant non-suggestive cues can help eleicit accurate information from them
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Ceci and Bruck (1993) factors that affect EWT

  • Interviewer bias: interviewer has fixed idea about what happened
  • Repeated questions: young children more likely to change answers when same question is repeated
  • Stereotype induction: children may come to assume and report bad things about someone based on what they had previously heard
  • encouragement to imagine: children may remember things that never actually happened
  • peer pressure: can influence what children report and may incorporate events that others have told them about 
  • authority figures: children may become susceptible to misleading information in their desire to please an authority figure
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Use of leading questions in EWT

  • "Leading questions" refers to question worded in a way that it might bias how a respondent answers
  • Research has shown subtle changes to the wording of a question can affect EWT
  • Loftus and Palmer (1974) showed participants film of car accident and asked questions
  • one question "How fast were the cars going when they hit eachother?"
  • all participants asked same type of question, word "hit" replaced with "smashed", "collided", "bumped", "contacted"
  • a week later, when asked if they had seen any broken glass, those in "smashed" group more likely to answer yes
  • Conclusions were that the word used had a significant affect on the estimation of speed
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Misleading information and the Cognitive Interview

Effects of misleading information:

  • Elizabeth Loftus particiularly interested in the effects on memory of information provided after the event
  • many studies were carried out showing memory for events can be changed or supplemented by providing misleading information later
  • usually takes form of question or statement that wrongly implies something happened when it didn't
  • Research of misleading information after the event

Loftus (1975) showed 150 participants a film of a car accident. After they had seen the film, participants got divided into 2 groups and each group was asked 10 questions about what they'd seen 

  • group 1 asked 10 qs which were consistent with film 
  • group 2 asked same qs except one about a barn. misleading as no barn was in the film
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Research on misleading information after the event

After 1 week, participants asked further 10 questions and both groups asked final question "Did you see a barn?"

Loftus found the following:

  • only 2.7% of participants in group 1 gave incorrect answer Yes to question about barn
  • 17.3% of those in group 2 (those given the misleading question) answered Yes
  • Loftus concluded that for those in group 2, the non-existent barn had been added to original memory representation of the event so that it was now recalled as being part of the original event
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The Cognitive Interview

  • In view of finding that accounts from eyewitnesses are often incomplete, psychologists have attempted to develop memory retrieval techniques that aim at eliciting more accurate information
  • 1 example: Cognitive Interview Schedule developed by Geiselman et al (1985)
  • Technique is based on 4 instructions:
  • Recreate the CONTEXT:  doesn't involve revisiting scene of crime, trying to recall image of the setting including details such as the weather, lighting, distinctive smells
  • report EVERYTHING: required to report any information you can remember even if it doesn't seem relevant to you at the time
  • Recall the event in a DIFFERENT ORDER: encouraged to describe events in reverse order
  • Change PERSPECTIVES: asked to attempt to describe incident from perspective of other people who were present at the time
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Strategies for memory improvement

  • Important application of memory theory in every day life is memory improvement
  • trick in improving memory is to develop and practice strategies that enhance recall
  • psychologists have plenty advice to offer
  • pay attention
  • use elaborative rehearsal
  • organization
  • avoid interference effects
  • use the encoding specificity principle
  • use mnemonics
  • space your studies
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Memory improvement strategies in more detail

Paying attention:

  • If you are serious about remembering something you need to attend to it
  • important to avoid distractions and focus on what you need to learn
  • while studying on your own important to chose a location that helps you concentrate

Use of elaborative rehearsal:

  • Maintenance rehearsal:strategy often used by young children involving children simply repeating information over and over again
  • only helps maintain information for a few seconds
  • more elaborate forms of rehearsal are required to encode successfully into LTM
  • elaborated memories are easier to recall because several different routes can be used to reach items in memory
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Memory improvement strategies continued


  • organising information into meaningful chunks can increase the capacity of STM
  • to improve LTM, helpful to create hierarchies to organise material into meaningful patterns
  • the most meaningful hierarchies are the ones you create for yourself

Avoid interference effects:

  • one of most important factors that can impair retrieval of information is interference from similar material
  • retroactive interference: when new information interferes with old infomation
  • proactive interference: when an old memory trace disrupts new information
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The use of mnemonics in memory improvement

  • Mnemonics are improvement techniques based on encoding information in special ways
  • techqniues are useful for remembering things such as shopping lists
  • most mnemonic devices have 2 key features:
  • a good encoding technique leading to a strong memory trace being established
  • effective retrieval cues

Method of Loci:

  • need to identify set of familiar places that you can imagine walking through
  • number of items you need to remember matches number of objects/places you choose
  • each item it converted to the thing you want to remember and placed in your location
  • locations act as a retrieval cue because you know them well

Peg word method:
- based on same principles as method of loci
- each number is assigned to a word acting as a retrieval cue for that piece of information  

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