Long-term Memory

1
Long-term Memory

• Multi-store model proposed by Atkinson and
  Shiffrin (1968) suggested that there is a single
  long-term memory store.
• Critics have argued that this model is
  over-simplified and that it is improbable that
  all the knowledge we possess is stored in exactly
  the same form in one store.
• Much research has been carried out to determine
  the number and nature of long-term memory stores

2
Long-term Memory

• Episodic and semantic memory
• Tulving (1972) argued for a distinction between
  episodic and semantic memory
• Episodic memory autobiographical- refers to
  storage of specific events or episodes. E.g.
  party you attended last weekend.
• Semantic memory general knowledge about the
  world e.g. facts and figures, language, etc.

3
Long-term Memory

• Tulving (1972, p.386) defined semantic memory as
• a mental thesaurus, organised knowledge a person
  possesses about words and other verbal symbols,
  their meanings and referents, about relations
  among them, and about rules, formulas, and
  algorithms for the manipulation of these symbols,
  concepts and relations

4
Long-term Memory

• Distinction between semantic and episodic memory
  can be described in the following way
• Episodic Wedding- remember who you went with,
  what various people wore, meal and party
  afterwards
• Semantic Knowledge of wedding ceremonies- e.g.
  usually in Church, sometimes registrar, legal
  ceremony which results in marriage, traditional
  wear for female is.., etc etc

5
Long-term Memory

• Tulving (1989) carried out a study to investigate
  the distinction between episodic and semantic
  memory
• A small dose of radioactive gold was injected
  into the bloodstream of participants (including
  Tulving).
• Participants instructed to think about personal
  events OR general knowledge (e.g. history of
  psychology)
• Blood flow in different areas of the brain
  recorded

6
Long-term Memory

• Tulving (1989)
• Results
• Episodic memory associated with a high level of
  activation in the frontal cortex
• Semantic memory associated with a high level of
  activation in the posterior or back regions of
  the cortex
• Evidence supports Tulvings view that there are
  separate long-term memory systems
• Evaluation difference in content of memories yet
  less clear that there is a difference in the
  processes involved. E.g. both rely heavily on
  each other

7
Long-term Memory

• Explicit and Implicit memory
• Memory tests involve the use of direct
  instructions to participants to retrieve specific
  information (e.g. free recall, cued recall,
  recognition)
• These tests are tests of explicit memory which,
  according to Graf and Schachter (1985) can be
  contrasted with implicit memory
• Explicit memory is revealed when performance on
  a task requires conscious recollection of
  previous experiences
• Implicit memory is revealed when performance on
  a task is facilitated in the absence of conscious
  recollection

8
Long-term Memory

• Explicit memory based on conscious recollection
• Implicit memory not based on conscious
  recollection
• How does one measure implicit memory?
• Why is this distinction important?

9
Long-term Memory

• Distinction useful when studying patients
  suffering from amnesia (partial loss of long-term
  memory usually caused by brain damage)
• Patients have severe problems with long-term
  memory- yet mainly with explicit rather than
  implicit memory
• Claparede (1911) hid a pin in his hand before
  shaking hands with an amnesic patient.
• After this, the patient was reluctant to shake
  hands but was embarrassed as she could not
  explain this reluctance
• Behaviour indicated implicit memory- this
  occurred in the absence of explicit memory of the
  accident

10
Long-term Memory

• Graf, Squire and Mandler (1984) tested memory in
  amnesic patients (and controls) for list words in
  four ways
• 3 standard explicit memory tests (cued recall,
  free recall, recognition)
• 1 implicit memory test word completion task
• Participants given three-letter word fragments
  (e.g. STR----) and asked to write down the first
  word they can think of beginning with these
  letters
• Implicit memory measured by extent to which the
  word completions match words from a previous list
• Results found that amnesic patients performed
  worse than controls on the explicit memory tasks.
  Yet performed as well as controls on the implicit
  memory test

11
Long-term Memory

• Declarative and procedural knowledge systems
• Cohen and Squire (1980) argued for a distinction
  between two long-term memory stores containing
  different types of knowledge
• Declarative knowledge knowing that e.g. what
  you had for lunch yesterday and capital of
  France.
• Procedural knowledge knowing how e.g. how to
  ride a bicycle, swim, drive a car.
• Explicit memory depends on declarative knowledge
• Implicit memory depends on the procedural
  knowledge system

12
Long-term Memory

• Declarative and procedural knowledge systems
• Cohen and Squire (1980) argue that amnesic
  patients have severe impairment of the
  declarative memory system and therefore find it
  hard to acquire new episodic and semantic
  memories.
• Yet amnesic patients find it relatively easy to
  acquire new skills which rely on procedural
  memory e.g. dress-making, jigsaw completions,
  (Eysenck and Keane, 1995)

13
Long-term Memory

• Declarative and procedural knowledge systems
• Squire, Knowlton and Musen (1993) argued that the
  main brain structures underlying declarative or
  explicit memory are located in the hippocampus,
  medial temporal lobes and the diencephalons.
• Study by Squire et al (1992) supported this view.
  Using PET scans, found that blood flow in the
  right hippocampus was much higher when
  participants were performing a cued recall task
  compared to a word-completion task.

14
Long-term Memory

• Summary
• Semantic and Episodic
• Explicit and Implicit
• Procedural and declarative
• Draw a model of LTM to incorporate these
  distinctions.

15
Forgetting

• The term forgetting has several meanings
• The information was never stored problem of
  availability
• The information was stored, but is difficult to
  retrieve problem of accessibility
  (tip-of-the-tongue)
• Confusion problem of interference
• Absentmindedness problem of habit, attention,
  and automatic responses.
• Generally, forgetting is the inability to recall
  or recognise material which was previously stored
  in memory.

16
Forgetting

• Trace Decay 
• According to the decay theory, information is
  forgotten because of the passage of time.
• Theoretical assumption that forgetting depends on
  the length of the retention interval rather than
  on events occurring during that interval.

17
Forgetting

• Peterson and Peterson, (1959) found that memories
  were held in short-term memory for approximately
  18 seconds, after which they disappeared via
  trace decay.
•  
• Hebb (1949) believed that, as a result of
  excitation of the nerve cells, a brief memory
  trace is laid down. At this stage the trace is
  very fragile and likely to be disrupted. With
  repeated neural activity (via rehearsal), a
  permanent structural change occurs and the memory
  is transferred to the long-term memory where it
  is no longer likely to decay.

18
Forgetting

• Displacement
•  
• Displacement refers to the limited number of
  slots in short-term memory (7/-2). When more
  items are introduced into short-term memory than
  there are slots, some of the old information must
  be knocked out of its slot, or displaced.
•  
• Evidence for this comes from the Brown-Peterson
  technique, where the last few words on a list are
  displaced from short-term memory by the counting
  task.
•  

19
Forgetting

• Decay vs Displacement
• Waugh and Norman (1965) used serial probe
  technique to investigate forgetting in STM. 16
  digits read out loud, last number is the probe
  but also occurs elsewhere in the list- asked to
  recall number that came after first occurrence of
  probe in list- manipulate position to investigate
  displacement.
• 4 participants listened to 90 lists read at slow
  (1 per sec) or fast rate (4 per sec). If decay is
  correct, fewer digits should be recalled in slow
  condition, if displacement correct rate should
  have no effect.

20
Forgetting

• Decay vs Displacement
• Results
• Position- participants recalled items near end of
  list better (80) than at start (20) evidence
  for both? Less interference and still in STM?
• Rate- when probe was late recall slightly better
  for fast list.
• Conclusion most forgetting in STM can be
  explained by displacement and some due to decay.
• Criticisms?

21
Forgetting

• Decay vs Interference in LTM
• Baddeley and Hitch (1977) natural (quasi)
  experiment carried out to investigate recall of
  rugby fixtures in one season.
• Some players missed games but time interval same
  for all. Number of intervening games different.
• If decay theory correct all players should recall
  similar .
• Results The more games played the more they
  forgot- supports interference theory.

22
Forgetting

•  Interference
• The idea behind this theory is that memories may
  be interfered with either by what has been
  learned before, or by what may be learned in the
  future. Forgetting increases with time because of
  interference from competing memories that have
  been acquired over time.
• Proactive interference when previous learning
  interferes with later learning and retention
• Retroactive interference when later learning
  disrupts memory for earlier learning

23
Forgetting

• Interference was widely studied in the 1960s, but
  has attracted less attention since then.
• Studies typically made use of the technique of
  paired-associates in which a word is associated
  with one word on a list and with a completely
  different word on another list.

24
Forgetting

• Participants are required to learn one list and
  then the other. When given the stimulus word from
  the first list, it was found that participants
  frequently suffered from retroactive
  interference, in other words, they recalled the
  paired associate from the second list.
• In both cases of interference, the greater the
  similarity of the interfering material, the
  greater the interference (Underwood and Postman,
  1960).

25
Forgetting

• Interference theory Evaluation
• Prediction learning a second response to a given
  stimulus causes the first response to be
  unlearned.
• Slamecka (1966) asked participants to produce
  free associates to various stimulus words.
• These stimulus words were then paired with new
  responses.
• When participants asked to recall their free
  associates, no sign of retroactive interference.

26
Forgetting

• Interference theory Evaluation
• Uninformative about internal processes involved
  in memory and learning
• Requires special circumstances for interference
  effects to occur (same stimulus and two different
  responses) which rarely happens in real life.

27
Forgetting

• Decay, interference and displacement theories all
  examples of trace dependent forgetting- the
  memory trace is no longer available.
• Many theorists have tried to understand why
  recognition memory is usually much better than
  recall (Parkin, 1993)
• Two-process theory (Watkins and Gardiner, 1979)
  suggests that
• Recall involves a search or retrieval process
  followed by a decision or recognition process
  based on the appropriateness of the information

28
Forgetting

• Cue-dependent Forgetting
• Tulving (1974) 2 major reasons for forgetting
• Trace dependent forgetting information no longer
  stored in memory (e.g. trace decay theory)
• Cue-dependent forgetting information in memory
  but cannot be accessed
• Tulving assumed basic similarities between recall
  and recognition and that contextual factors were
  important (memory contains information about
  material and context)

29
Forgetting

• Cue-dependent Forgetting
• Tulving and Pearlstone (1966)
• Long lists of words belonging to several
  different categories were presented (e.g.
  animals, furniture etc)
• Participants asked to write down what they could
  remember (non-cued recall)
• Participants given category names and asked to
  write down what they could remember
• Results participants recalled up to three or
  four times as many words with cued recall

30
Forgetting

• Cue-dependent Forgetting
• External cues e.g. category names
• Internal cues e.g. mood state
• state-dependent forgetting research (eg Goodwin
  et al, 1969) showed that information is more
  likely to be remembered by an individual if they
  are in the same physical or emotional sate as
  they were in when they learned it.
• Effects are stronger when participants are in a
  positive mood than a negative mood (Ucros, 1989)

31
Forgetting

• Cue-dependent Forgetting
• Findings on cue-dependent forgetting and
  mood-state dependent memory indicate that
  forgetting occurs when the information available
  at the time of retrieval does not match or fit
  information in memory trace.
• Tulving (1979) proposed the encoding specificity
  principle
• The probability of successful retrieval of
  the target item is anincreasing function of
  informational overlap between the information
  contained in the retrieval cue and the
  information stored in memory.

32
Forgetting

• Cue-dependent Forgetting
•          context-dependent forgetting research
  (eg. Abernathy, 1940) has shown that it is much
  easier to remember information in the same
  context in which the information was learnt.
• Also remembering information is made easier with
  retrieval cues which trigger memory for relevant
  information.
• Tulving assumes that context affects recall and
  recognition in the same way- but is this the case?

33
Forgetting

• Baddeley (1982) proposed a distinction between
  intrinsic context and extrinsic context
• Intrinsic context has direct impact on meaning
  or significance of a to-be-remembered item (e.g.
  strawberry vs traffic as intrinsic context for
  the word jam.
• Extrinsic context e.g. room in which learning
  takes place does not.
• Recall affected by both, recognition affected
  only by intrinsic context

34
Forgetting

• Godden and Baddeley (1975)
• Participants learned a list of words either on
  land or 20feet underwater.
• Then given a test of free recall on land or
  underwater.
• Results those who learned on land recalled more
  on land and those who learned underwater recalled
  more underwater
• Recall 50 higher when learning took place in the
  same extrinsic context

35
Forgetting

• Godden and Baddeley (1980)
• Similar study- tested recognition memory instead
  of recall
• Results recognition memory not affected by
  extrinsic context e.g. did not matter if they
  learned words on land and tested underwater

36
Forgetting

• Emotional Factors in Forgetting 
• Repression
• Repression is a concept from psychoanalytic
  psychology which focuses heavily on emotion.
  Freud (1915) proposed that forgetting is
  motivated by the desire to avoid displeasure, so
  embarrassing, unpleasant or anxiety-producing
  experiences are repressed pushed down into the
  unconscious.
•  

37
Forgetting

• Emotional Factors in Forgetting 
• Repression is an unconscious, protective defence
  mechanism, which involves the ego actively
  blocking the conscious recall of memories which
  become inaccessible.
•  

38
Forgetting

• Emotional Factors in Forgetting 
• Repression
• Case studies provide examples of repression.
  Freud reports the case of a man who kept
  forgetting the line With a white sheet. Free
  association revealed that the term white sheet
  was associated with the sheet placed over a
  corpse. The mans friend had recently died from a
  heart attack and the white sheet was associated
  with death this made him fearful since he was
  overweight and his grandfather had died of a
  heart attack.
•  
• Repression has proved difficult to demonstrate in
  a laboratory but attempts have been made

39
Forgetting

• Levinger and Clark (1961) investigated the
  retrieval of associations to words that were
  emotionally charged, compared with the retrieval
  of associations to neutral words. They found
•          It took participants longer to provide
  free associations to the negatively charged words
  compared with the neutral words.

40
Forgetting

•          Compared with the neutral words, the
  negatively charged words produced higher galvanic
  skin responses in the participants.
•          Participants found it more difficult to
  recall their associations for the negatively
  charged words compared with the neutral words.
•  
• From these findings, Levinger and Clark concluded
  that repression led to the emotionally negatively
  charged words being more difficult to recall and
  results therefore, support Freuds theory that
  repression causes forgetting.

41
Forgetting

• However, a situation of high anxiety was produced
  by Loftus and Burns (1982) who showed two groups
  a film of a bank robbery, but exposed one of the
  groups to a far more violent version where a
  young boy was shot in the face. The group that
  saw this version later showed far poorer recall
  of detail than the control group.
•  

42
Forgetting

• Loftus and Burns explained the forgetting with
  the weapons focus effect, where fearful or
  stressful aspects of a scene (eg the gun) channel
  attention towards the source of distress and away
  from other details.
• Alternatively, people may need to be in the same
  state (ie anxious) to recall properly this is a
  cue-dependent explanation.
• Emotion may also be used to explain why we
  remember..

43
Forgetting

• Flashbulb Memories
•  
• The term flashbulb memory describes a
  long-lasting vivid memory formed at a time of
  intense emotion, such as significant public or
  personal events.
•  
• Brown and Kulik (1977) found that around 90 of
  people reported flashbulb memories associated
  with personal shocking events, but whether they
  had such memories for public shocking events,
  like assassinations, depended upon how personally
  relevant the event was for them. 75 of black
  participants in their research had a flashbulb
  memory for the assassination of Martin Luther
  King, compared to 3 of white participants.

44
Forgetting

• Flashbulb Memories
•   
• Brown and Kulik argue that flashbulb memory was a
  special and distinct form of memory since the
  emotionally important event triggers a neural
  mechanism, which causes it to be especially well
  imprinted into memory.
•  
• Neisser (1982), disagrees that flashbulb memories
  are distinct from other memories, since the
  long-lasting nature of the memory is probably due
  to it being frequently rehearsed (thought about
  it and discarded afterwards) rather than being
  due to any special neural activity at the time.

45
Memory Improvement Techniques

• Improving the memory depends on organising
  information and then using active techniques and
  persevering with them.
• Organisation
• Organising and ordering information can
  significantly improve memory.

46
Memory Improvement Techniques

• By Category and Hierarchy
• If things are stored away in their proper place
  it is much easier to find them than when they are
  jumbled up.
• Memory is the same, retrieval is made easier when
  memory is organised rather than if it is
  disorganised.
• Information can be accessed more easily if it is
  organised by category and hierarchy.

47
Memory Improvement Techniques

• Conceptual hierarchy
• Bower et al. (1969) presented participants with
  112 words to learn.
• Condition 1 words organised into conceptual
  hierarchies (e.g. metals- common, rare and
  alloys)
• Condition 2 random order
• The results showed that the list, which was
  arranged hierarchically was recalled two to three
  times better than the list arranged randomly.

48
Memory Improvement Techniques

• Visual Imagery
• Imagery can be defined as the creation of a
  mental picture.
• Diagrams can be used to illustrate information
  and to aid understanding of information.
• Visual imagery also serves to organise
  information
• Bower, 1972- pps given 100 cards with 2 unrelated
  words on each (cat/brick)
• Condition 1-pps had to produce mental image
  linking the two words Condition 2- no
  instruction
• Results- in a cued recall test the imagers
  recalled 80 of words compared with 45 in
  condition 2.

49
Memory Improvement Techniques

• After studying patients with damage to one of
  their temporal lobes, Paivio (1971) proposed that
  the processing of words and images occurs
  separately. According to Paivio, concrete words,
  which can be images, are encoded twice in memory,
  once in verbal symbols and once as image-based
  symbols. This increases the likelihood that they
  will be remembered.
• Paivio called this the dual coding hypothesis.
  (This can be linked to the phonological loop and
  visuo-spatial sketch pad systems in the Working
  memory model.)

50
Memory Improvement Techniques

• By Context
• It is easier to retrieve a particular episode if
  you are in the same context as that in which the
  episode occurred (Estes, 1972).
• Context has been shown to affect our memory in
  several ways.
• Godden and Baddeley (1975) presented divers with
  material to learn, either on dry land or
  underwater. Subsequent retrieval was best when
  the recall environment matched that of the
  original learning.
• In state-dependent learning the internal state of
  the individual provides the contextual cue for
  retrieving information.

51
Memory Improvement Techniques

• Context and state dependency relates to
  cue-dependent recall.
• Applied? Reduce notes to bullet points- one or
  two words which are cues to trigger a whole
  string of information.
• Tulving and Psotka (1971) study investigated
  interference (1-6 word lists-24 in each list) and
  cued recall (over 6 lists 36 categories)
• After each list, free recall. After all lists
  final free recall followed by category names
  (cued recall).

52
Memory Improvement Techniques

• Those given 1 or 2 lists remembered more than
  those given 6- evidence for interference theory?
• Yet, after cued recall interference effects
  disappeared- pps remembered about 70 regardless
  of how many lists they were given.
• Information is there (available) but cannot be
  retrieved-cue dependent forgetting
• Tulving suggests that elementary units are
  organised into higher order units (categories)
  access our memories in a hierarchial manner

53
Memory Improvement Techniques

•          Repetition
•  
• Practice makes perfect the more times
  information is memorised, the more accurate the
  recall and the less time it takes to re-learn the
  material.
• Ebbinghaus (1895) found re-learning savings the
  greater the number of repetitions the less time
  it took to re-learn the lists.
•  
• Linto found that everyday memories last longer if
  they are occasionally remembered.

54
Memory Improvement Techniques

• Elaborative rehearsal
• Maintenance rehearsal- rote repetition
• Elaborative rehearsal- not the amount but nature
  of rehearsal that is important.
• Material is expanded and manipulated in order to
  increase its meaningfulness-semantic processing
• Process of adding extra cues to new information
  at the time when we encode it (multiple
  encoding) so that we have multiple pathways to
  the information at the time when we need to
  retrieve it.

55
Memory Improvement Techniques

• Craik and Tulving (1975)   Elaborative rehearsal
• Elaboration manipulated by varying the complexity
  of the sentence frame between simple (She cooked
  the ------)
• and complex (The great bird swooped down and
  carried off the struggling ------)
• Results
• Cued recall twice as high for words accompanying
  complex sentences
• Suggests that elaboration benefits long-term
  memory
• Later studies have found that type of elaboration
  and not just amount of elaboration is important
  (Bransford et al, 1979)

56
Mnemonics

•          Mnemonics try to improve organisation
  when encoding takes place.
•  
• They are a combination of loci, associations and
  imagery.
• There are several well-known mnemonic systems

57
Mnemonics

• Method of Loci (using familiar locations-eg
  shopping list)
• Numeric pegword system (link items to
  pegs-locations-e.g. one is a bun rhyme)
• Keyword method (new keyword acts as retrieval cue
  e.g. learning the French word for library-bible)
• Narrative link (link otherwise unrelated words in
  a story)
• Rhymes and rhythms (times table rhymes)

58
Mnemonics

• Grouping classify lists on the basis of some
  common characteristic. Remembering the key
  element of the group is a key to remembering all
  the items. An example would be grouping trees by
  deciduous or evergreen. (e.g. Bowers 1969
  study).

59
Mnemonics

•                Rhymes setting the information
  to be remembered to a rhyme eg in 1492 Columbus
  sailed the ocean blue.
• Other examples of mnemonics using rhyming
  include
•          I before E except after C or
•          30 days hath September, April, June
  and November.
• It seems that the rhythmic pattern helps by
  reducing the number of retrieval possibilities.

60
Mnemonics

•             Acronyms the first letter from
  each word in a list forms a key word, name, or
  sentence, eg PALM, SFA and NAB
• Acrostics- first letter in each line or word
  forms the item e.g. every good boy deserves
  food for the lines on the treble clef.
• Chaining material to be learned into
  narrative stories can also help remembering.
  Bower and Clark (1969) asked participants to make
  stories from lists of ten un-related nouns.
  Subsequently, 93 showed correct recall.

61
Mnemonics

•      Mnemonics help memory by shortening the
  sequence to be learned or elaborating it, and
  giving it meaning.
•  
• They do have drawbacks
•          they do not help to understand the
  material
•          they are time consuming to learn
•          under stress the mnemonic may be
  forgotten and therefore the information.
•  

62
Mnemonics

•      What about strategies for learning complex,
  integrated material?
• Mind Maps
• Mind mapping involves writing down a central idea
  and thinking up new and related ideas out from
  the centre. By focusing on key ideas written down
  and then looking for branches out and connections
  between the ideas, knowledge is mapped in a
  manner which will aid learning and recall (Buzan,
  1993).

63
Mnemonics

•      PQRST Method
• Preview, Question, Read, Self- recitation and
  Test
• Designed to help improve ability to study and
  remember material from textbooks
• With reference to research evidence, describe and
  evaluate memory improvement techniques and their
  application to study and exam skills. (12 ku,
  8ae)/