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 Tulving’s 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 an…increasing 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 avoiddispleasure, 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 man’s 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 Freud’s 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.