Study of memory in psychology


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Study of memory in psychology

  1. 1. Study of Memory in PsychologyDr. Magda FahmyProfessor of PsychiatrySuez Canal
  2. 2. • “Memory is the process of maintaininginformation over time.” (Matlin, 2005)• “Memory is the means by which we draw onour past experiences in order to use thisinformation in the present.’ (Sternberg, 1999)
  3. 3. • Memory is the term given to the structuresand processes involved in the storage andsubsequent retrieval of information.• Memory is involved in processing vastamounts of information. This informationtakes many different forms, e.g. images,sounds or meaning.
  4. 4. 1. Encoding and Memory• When information comes into our memorysystem (from sensory input), it needs to bechanged into a form that the system can copewith, so that it can be stored. (Think of this assimilar to changing your money into a differentcurrency when you travel from one country toanother).• For example, a word which is seen (on thewhiteboard) may be stored if it is changed(encoded) into a sound or a meaning (i.e.semantic processing).
  5. 5. 1. Encoding and Memory• There are three main ways in whichinformation can be encoded (changed):• 1. Visual (picture)• 2. Acoustic (sound)• 3. Semantic (meaning)
  6. 6. 1. Encoding and Memory• For example, how do you remember atelephone number you have looked up in thephone book? If you can see it then you areusing visual coding, but if you are repeating itto yourself you are using acoustic coding (bysound).
  7. 7. 1. Encoding and Memory• Evidence suggests that this is the principle codingsystem in short term memory (STM) is acousticcoding.• When a person is presented with a list ofnumbers and letters, they will try to hold them inSTM by rehearsing them (verbally).• Rehearsal is a verbal process regardless ofwhether the list of items is presented acoustically(someone reads them out), or visually (on a sheetof paper).
  8. 8. 1. Encoding and Memory• The principle encoding system in long termmemory (LTM) appears to be semantic coding(by meaning). However, information in LTMcan also be coded both visually andacoustically.
  9. 9. 2. Storage and Memory• This concerns the nature of memory stores, i.e.where the information is stored, how long thememory lasts for (duration), how much can bestored at any time (capacity) and what kind ofinformation is held.• The way we store information affects the way weretrieve it.• There has been a significant amount of researchregarding the differences between Short TermMemory (STM ) and Long Term Memory (LTM)
  10. 10. 2. Storage and Memory• Most adults can store between 5 and 9 itemsin their short-term memory.• Miller put this idea forward and he called itthe magic number 7.• He though that short-term memory capacitywas 7 (plus or minus 2) items because it onlyhad a certain number of “slots” in which itemscould be stored.
  11. 11. 2. Storage and Memory• Short-term memory: Miller didn’t specify theamount of information that can be held in eachslot. Indeed, if we can “chunk” informationtogether we can store a lot more information inour short-term memory.• In contrast the capacity of LTM is thought to beunlimited.• Information can only be stored for a briefduration in STM (0-30 seconds), but LTM can lasta lifetime.
  12. 12. 3. Retrieval and Memory• This refers to getting information out storage.If we can’t remember something, it may bebecause we are unable to retrieve it.• When we are asked to retrieve somethingfrom memory, the differences between STMand LTM become very clear.
  13. 13. 3. Retrieval and Memory• STM is stored and retrieved sequentially. Forexample, if a group of participants are given a listof words to remember, and then asked to recallthe fourth word on the list, participants gothrough the list in the order they heard it in orderto retrieve the information.• LTM is stored and retrieved by association. Thisis why you can remember what you went upstairsfor if you go back to the room where you firstthought about it.
  14. 14. 3. Retrieval and Memory• Organizing information can help aidretrieval. You can organize information insequences (such as alphabetically, by size or bytime).• Imagine a patient being discharged form hospitalwhose treatment involved taking various pills atvarious times, changing their dressing and doingexercises. If the doctor gives these instructions inthe order which they must be carried outthroughout the day (i.e. in sequence of time), thiswill help the patient remember them.
  15. 15. The multi store model• The multi store model (Atkinson and Shiffrin,1968) is a classic model of memory. It issometimes called the modal model or the dualprocess model.• Atkinson and Shiffrin (1968) suggest thatmemory is made up of a series of stores.
  16. 16. The multi store model(Atkinson and Shiffrin 1968)• The multi store model (Atkinson and Shiffrin 1968)describes memory in terms of information flowingthrough a system.• Information is detected by the sense organs and entersthe sensory memory.• If attended to this information enters the short termmemory.• Information from the STM is transferred to the long-term memory only if that information is rehearsed.• If rehearsal does not occur, then information isforgotten, lost from short term memory through theprocesses of displacement or decay.
  17. 17. The multi store model
  18. 18. Sensory Memory• Duration: ¼ to ½ second• Capacity: all sensory experience (v. largercapacity)• Encoding: sense specific (e.g. different storesfor each sense)
  19. 19. Short term memory• Duration: 15 and 30 seconds• Capacity: 7 +/- 2 items• Encoding: mainly auditory
  20. 20. Long term memory• Duration: Unlimited• Capacity: Unlimited• Encoding: Mainly Semantic (but can be visualand auditory)
  21. 21. Short Term Memoryby Saul McLeod published 2009Short term memory has three key aspects:1. limited capacity (only about 7 items can bestored at a time)2. limited duration (storage is very fragile andinformation can be lost with distraction orpassage of time)3. encoding (primarily acoustic, even translatingvisual information into sounds).
  22. 22. Short Term Memory• There are two ways in which capacity is tested, onebeing span, the other being recency effect.• Miller’s (1956) Magic number 7 (plus or minus two)provides evidence for the capacity of short termmemory.• Most adults can store between 5 and 9 items in theirshort-term memory. This idea was put forward byMiller (1956) and he called it the magic number 7. Hethough that short term memory could hold 7 (plus orminus 2 items) because it only had a certain number of“slots” in which items could be stored.
  23. 23. Short Term Memory• The duration of short term memory seems tobe between 15 and 30 seconds, according toAtkinson and Shiffrin (1971).• Items can be kept in short term memory byrepeating them verbally (acoustic encoding), aprocess known as rehearsal.
  24. 24. Short Term Memory• Using a technique called the Brown-Petersontechnique which prevents the possibility ofretrieval by having participants count backwardsin 3s, Peterson and Peterson 1959 showed thatthe longer the delay, the less information isrecalled.• The rapid loss of information from memory whenrehearsal is prevented is taken as an indication ofshort term memory having a limited duration.
  25. 25. Why We Remember What WeRemember• Short Term Memory. There are typically six reasonswhy information is stored in our short term memory.• 1. primacy effect information that occurs first istypically remembered better than informationoccurring later. When given a list of words or numbers,the first word or number is usually remembered due torehearsing this more than other information.• 2. recency effect - often the last bit of information isremembered better because not as much time haspast; time which results in forgetting.
  26. 26. • 3. distinctiveness - if something stands out frominformation around it, it is often rememberedbetter. Any distinctive information is easier toremember than that which is similar, usual, ormundane.• 4. frequency effect - rehearsal, as stated in thefirst example, results in bettermemory. Remember trying to memorize aformula for your math class. The more you wentover it, the better you knew it.
  27. 27. • 5. associations - when we associate or attachinformation to other information it becomeseasier to remember. Many of us use this strategyin our professions and everyday life in the form ofacronyms .• 6. reconstruction - sometimes we actually fill inthe blanks in our memory. In other words, whentrying to get a complete picture in our minds, wewill make up the missing parts, often without anyrealization that this is occurring.
  28. 28. • Baddeley and Hitch (1974) have developed analternative model of short-term memorywhich they call working memory.
  29. 29. The multi store model• Environmental input sensory memory(Attention) working memoryRehearsal Retrievallong term memory
  30. 30. working memory• Working memory is STM. Instead of allinformation going into one single store, thereare different systems for different types ofinformation.• Working memory consists of a centralexecutive which controls and co-ordinates theoperation of two subsystems:1- phonological loop and2- visuo-spatial sketchpad.
  31. 31. working memoryCentral Executive: Drives the whole system (e.g.the boss of working memory) and allocatesdata to the subsystems (VSS & PL). It alsodeals with cognitive tasks such as mentalarithmetic and problem solving.• A. Visuo-Spatial Sketch Pad (inner eye):Stores and processes information in a visualor spatial form. The VSS is used for navigation.
  32. 32. • B. The phonological loop is the part ofworking memory that deals with spoken andwritten material. It can be used to remembera phone number. It consists of two parts1. Phonological Store (inner ear) – Linked to speech perceptionHolds information in speech-based form (i.e. spoken words)for 1-2 seconds.2. Articulatory control process (inner voice) – Linked to speechproduction. Used to rehearse and store verbal informationfrom the phonological store.
  33. 33. • The phonological loop is assumed to beresponsible for the manipulation of speechbased information.• The visuo-spatial sketchpad is assumed to beresponsible for manipulating visual images.• The model proposes that every component ofworking memory has a limited capacity, andalso that the components are relativelyindependent of each other.
  34. 34. Empirical Evidence for the WorkingMemory Model• What evidence is there that working memory exists,that it is made up of a number of parts, that itperforms 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 workingmemory), they cannot be performed successfully together.• 2. If two tasks make use of different components, it should bepossible to perform them as well as together as separately.
  35. 35. Key Study: Baddeley and Hitch (1976)• Aim: To investigate if participants can use differentparts of working memory at the same time.• Method: Conducted an experiment in whichparticipants were asked to perform two tasks at thesame time (dual task technique) - a digit span taskwhich required them to repeat a list of numbers, and averbal reasoning task which required them to answertrue or false to various questions (e.g. B is followed byA?).
  36. 36. • Results: As the number of digits increased in thedigit span tasks, participants took longer toanswer the reasoning questions, but not muchlonger - only fractions of a second. And, theydidnt make any more errors in the verbalreasoning tasks as the number of digits increased.• Conclusion: The verbal reasoning task made useof the central executive and the digit span taskmade use of the phonological loop.
  37. 37. The Central Executive• The central executive is the most importantcomponent of the model, although little is knownabout how it functions.• It is responsible for monitoring and coordinatingthe operation of the slave systems (i.e. visuo-spatial sketch pad and phonological loop) andrelates them to long term memory (LTM).• The central executive decides which informationis attended to and which parts of the workingmemory to send that information to be dealtwith.
  38. 38. The Central Executive• The central executive decides what workingmemory pays attention to.• For example, two activities sometimes comeinto conflict such as driving a car and talking.Rather than hitting a cyclist who is wobblingall over the road, it is preferable to stoptalking and concentrate on driving. The centralexecutive directs attention and gives priorityto particular activities.
  39. 39. The Central Executive• Baddeley suggests that the central executive actsmore like a system which controls attentionalprocesses rather than as a memory store.• This is unlike the phonological loop and the visuo-spatial sketchpad, which are specialized storagesystems.• The central executive enables the workingmemory system to selectively attend to somestimuli and ignore others.
  40. 40. The Central Executive• Baddeley (1986, 1999) uses the metaphor of acompany boss to describe the way in whichthe central executive operates.• The company boss makes decisions aboutwhich issues deserve attention and whichshould be ignored. They also select strategiesfor dealing with problems, but like any personin the company, the boss can only do a limitednumber of things at the same time.
  41. 41. The Central Executive• The boss of a company will collect informationfrom a number of different sources. If wecontinue applying this metaphor, then we cansee the central executive in working memoryintegrating (i.e. combining) information fromtwo assistants (the phonological loop and thevisuo-spatial sketchpad) and also drawing oninformation held in a large database (long-term memory).
  42. 42. The phonological loop
  43. 43. The phonological loop• The phonological loop is the part of workingmemory that deals with spoken and writtenmaterial. It consists of two parts.• 1. The phonological store (linked to speechperception) acts as an inner ear and holdsinformation in speech-based form (i.e. spokenwords) for 1-2 seconds. Spoken words enter thestore directly. Written words must first beconverted into an articulatory (spoken) codebefore they can enter the phonological store.
  44. 44. The phonological loop• 2. The articulatory control process (linked tospeech production) acts like an inner voicerehearsing information from the phonologicalstore. It circulates information round andround like a tape loop. This is how weremember a telephone number we have justheard. As long as we keep repeating it, we canretain the information in working memory.
  45. 45. The phonological loop• The articulatory control process also convertswritten material into an articulatory code andtransfers it to the phonological store.
  46. 46. The Visuo-Spatial Sketchpad• The visuo-spatial sketchpad (inner eye) dealswith visual and spatial information.• Visual information refers to what things looklike. It is likely that the visuo-spatial sketchpadplays an important role in helping us keeptrack of where we are in relation to otherobjects as we move through our environment(Baddeley, 1997).
  47. 47. The Visuo-Spatial Sketchpad• As we move around, our position in relation toobjects is constantly changing and it isimportant that we can update thisinformation.• For example, being aware of where we are inrelation to desks, chairs and tables when weare walking around a classroom means thatwe dont bump into things too often!
  48. 48. The Visuo-Spatial Sketchpad• The sketchpad also displays and manipulatesvisual and spatial information held in long-termmemory.• For example, the spatial layout of your house isheld in LTM. Try answering this question: Howmany windows are there in the front of yourhouse? You probably find yourself picturing thefront of your house and counting the windows.An image has been retrieved from LTM andpictured on the sketchpad.
  49. 49. The Visuo-Spatial Sketchpad• Evidence suggests that working memory uses twodifferent systems for dealing with visual andverbal information.• A visual processing task and a verbal processingtask can be performed at the same time. It ismore difficult to perform two visual tasks at thesame time because they interfere with each otherand performance is reduced. The same applies toperforming two verbal tasks at the same time.
  50. 50. The Visuo-Spatial Sketchpad• This supports the view that the phonologicalloop and the sketchpad are separate systemswithin working memory.
  51. 51. Evaluation of Working Memory• Researchers today generally agree that short-term memory is made up of a number ofcomponents or subsystems. The workingmemory model has replaced the idea of aunitary (one part) STM as suggested by themultistore model.
  52. 52. Evaluation of Working Memory• The working memory model explains a lotmore than the multistore model.• It makes sense of a range of tasks - verbalreasoning, comprehension, reading, problemsolving and visual and spatial processing. Andthe model is supported by considerableexperimental evidence.
  53. 53. Evaluation of Working MemoryThe working memory applies to real life tasks:- Reading (phonological loop)- Problem solving (central executive)- Navigation (visual and spatial processing)
  54. 54. Evaluation of Working Memory• The KF Case Study supports the WorkingMemory Model. KF suffered brain damagefrom a motorcycle accident that damaged hisshort-term memory. KFs impairment wasmainly for verbal information - his memory forvisual information was largely unaffected. Thisshows that there are separate STMcomponents for visual information (VSS) andverbal information (phonological loop).
  55. 55. Evaluation of Working Memory• Working memory is supported by dual taskstudies (Baddeley and Hitch, 1976).• The working memory model does not overemphasize the importance of rehearsal forSTM retention, in contrast to the multi-storemodel.
  56. 56. Weaknesses of working memory model• Lieberman criticizes the working memorymodel as the visuo-spatial sketchpad (VSS)implies that all spatial information was firstvisual (they are linked). However, Liebermanpoints out that blind people have excellentspatial awareness although they have neverhad any visual information. Lieberman arguesthat the VSS should be separated into twodifferent components: one for visualinformation and one for spatial.
  57. 57. Weaknesses of working memory model• There is little direct evidence for how the centralexecutive works and what it does. The capacityof the central executive has never beenmeasured.• Working memory only involves STM so it is not acomprehensive model of memory (as it does notinclude SM or LTM).• The working memory model does not explainchanges in processing ability that occur as theresult of practice or time.
  58. 58. Long Term Memoryby Saul McLeod published 2010• Theoretically, the capacity of long termmemory could be unlimited, the mainconstraint on recall being accessibility ratherthan availability.• Duration might be a few minutes or a lifetime.• Suggested encoding modes are semantic(meaning) and visual (pictorial) in the mainbut can be acoustic also.
  59. 59. Long Term Memory• Bahrick et al (1975) investigated what they calledvery long term memory (VLTM). Nearly 400participants aged 17 – 74 were tested. Therewere various tests including:1. A free recall test, where participants tried toremember names of people in a graduate class.2. A photo recognition test, consisting of 50pictures.3. A name recognition test for ex-school friends.
  60. 60. Long Term Memory• Participants who were tested within 15 yearsof graduation were about 90% accurate inidentifying names and faces. After 48 yearsthey were accurate 80% for verbal and 70%visual.• Free recall was worse. After 15 years it was60% and after 48 years it was 30% accurate.
  61. 61. Long Term Memory• One of the earliest and most influentialdistinctions was proposed by Tulving(1972). He proposed a distinction betweenepisodic, semantic and procedural memory.
  62. 62. Long Term Memory• Procedural memory is a part of the long-termmemory is responsible for knowing how to dothings, i.e. memory of motor skills.• It does not involve conscious (i.e. it’sunconscious - automatic) thought is notdeclarative.• For example, procedural memory wouldinvolve knowledge of how to ride a bicycle.
  63. 63. Long Term Memory• Semantic memory is a part of the long-termmemory responsible for storing informationabout the world. This includes knowledgeabout the meaning of words, as well asgeneral knowledge. For example, London isthe capital of England. It involves consciousthought and is declarative.
  64. 64. Long Term Memory• Episodic memory is a part of the long-termmemory responsible for storing informationabout events (i.e. episodes) that we haveexperienced in out lives. It involves consciousthought and is declarative. An example wouldbe a memory of our 1st day at school.
  65. 65. Long Term Memory• Cohen and Squire (1980) drew a distinctionbetween declarative knowledge and proceduralknowledge.• Procedural knowledge involves “knowing how”to do things. It included skills, such as “knowinghow” to playing the piano, ride a bike; tie yourshoes and other motor skills. It does not involveconscious (i.e. automatic) thought. For example,we brush our teeth with little or no awareness ofthe skills involved.
  66. 66. Long Term Memory• Declarative knowledge involves “knowingthat”, for example London is the capital ofEngland, zebras are animals, your mumsbirthday etc. Recalling information fromdeclarative memory involves some degree ofconscious effort – information is consciouslybrought to mind and “declared”.
  67. 67. Long Term Memory• The knowledge that we hold in semantic andepisodic memories focuses on “knowing that”something is the case (i.e. declarative).• For example, we might have a semanticmemory for knowing that Paris is the capitalof France, and we might have an episodicmemory for knowing that we caught the busto college today.
  68. 68. Long Term Memory• Evidence for the distinction between declarativeand procedural memory has come from researchon patients with amnesia.• Typically, amnesic patients have great difficulty inretaining episodic and semantic informationfollowing the onset of amnesia. Their memory forevents and knowledge acquired before the onsetof the condition tends to remain intact, but theycan’t store new episodic or semantic memories.In other words, it appears that their ability toretain declarative information is impaired.
  69. 69. Long Term Memory• However, their procedural memory appears tobe largely unaffected. They can recall skillsthey have already learned (e.g. riding a bike)and acquire new skills (e.g. learning to drive).
  70. 70. • categorize memory as being explicit, which is defined asthat involved in the conscious recall of information aboutpeople, places, and things, or• implicit, which is characterized by the nonconscious recallof tasks such as motor skills.• Explicit memory depends on the integrity of temporal lobeand diencephalic structures such as the hippocampus,subiculum, and entorhinal cortex.• Implicit memory includes simple associative forms ofmemory, such as classical conditioning, and nonassociativeforms, such as habituation, and relies on the integrity ofthe cerebellum and basal ganglia (582).
  71. 71. Levels of Processingby Saul McLeod published 2007• The levels of processing model of memory(Craik and Lockhart, 1972) was put forwardpartly as a result of the criticism leveled at themulti-store model.• Instead of concentrating on thestores/structures involved (i.e. short termmemory & long term memory), this theoryconcentrates on the processes involved inmemory.
  72. 72. Levels of Processing• Unlike the multi-store model it is a non-structured approach. The basic idea is thatmemory is really just what happens as a resultof processing information.• Psychologists Craik and Lockhart propose thatmemory is just a by-product of the depth ofprocessing of information and there is no cleardistinction between short term memory andlong term memory.
  73. 73. Levels of Processing• Depth is defined as "the meaningfulnessextracted from the stimulus rather than interms of the number of analyses performedupon it.”
  74. 74. We can process information in 3 ways:• Shallow Processing• - This takes two forms• 1. Structural processing (appearance) which iswhen we encode only the physical qualities ofsomething. E.g. the typeface of a word orhow the letters look.• 2. Phonemic processing – which is when weencode its sound.
  75. 75. • Shallow processing only involves maintenancerehearsal (repetition to help us holdsomething in the STM) and leads to fairlyshort-term retention of information. This isthe only type of rehearsal to take place withinthe multi-store model.
  76. 76. • Deep Processing• - This involves• 3. Semantic processing, which happens whenwe encode the meaning of a word and relateit to similar words with similar meaning.
  77. 77. • Deep processing involves elaborationrehearsal which involves a more meaningfulanalysis (e.g. images, thinking, associationsetc.) of information and leads to better recall.For example, giving words a meaning orlinking them with previous knowledge.
  78. 78. Summary• Levels of processing: The idea that the wayinformation is encoded affects how well it isremembered. The deeper the level ofprocessing, the easier the information is torecall.
  79. 79. Application of the Levels ofProcessing Model in Real Life• This explanation of memory is useful ineveryday life because it highlights the way inwhich elaboration, which requires deeperprocessing of information, can aid memory.Three examples of this are.
  80. 80. • • Reworking – putting information in your ownwords or talking about it with someone else.• Method of loci – when trying to remember alist of items, linking each with a familiar place orroute.• Imagery – by creating an image of somethingyou want to remember, you elaborate on it andencode it visually (i.e. a mind map).
  81. 81. • The above examples could all be used torevise psychology using semantic processing(e.g. explaining memory models to your mum,using mind maps etc.) and should result indeeper processing through using elaborationrehearsal. Consequently more informationwill be remembered (and recalled) and betterexam results should be achieved.
  82. 82. • 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
  83. 83. Forgettingby Saul McLeod published 2008• Why do we forget? There are two simpleanswers to this question.First, the memory has disappeared - it is nolonger available.Second, the memory is still stored in the memorysystem but, for some reason, it cannot beretrieved.• The first answer is more likely to be applied toforgetting in short term memory, the second toforgetting in long term memory.
  84. 84. Forgetting• Forgetting information from short termmemory (STM) can be explained using thetheories of trace decay and displacement.• Forgetting from long term memory (LTM) canbe explained using the theories ofinterference and lack of consolidation.
  85. 85. Trace Decay Theory of Forgetting(STM)• This theory relates to both short termmemory and long term memory, and alsorelates to lack of availability.• This theory suggests short term memory canonly hold information for between 15 and 30seconds unless it is rehearsed. After this timethe information decays (fades away).
  86. 86. Trace Decay Theory• This explanation of forgetting in short termmemory assumes that memories leave a trace inthe brain.• A trace is some form of physical and/or chemicalchange in the nervous system.• Trace decay theory states that forgetting occursas a result of the automatic decay or fading of thememory trace.• Trace decay theory focuses on time and thelimited duration of short term memory.
  87. 87. Trace Decay Theory• memory tends to get worse the longer thedelay between learning and recall• The longer the time, the more the memorytrace decays and as a consequence moreinformation is forgotten.
  88. 88. Trace Decay Theory• in any real-life situation, the time betweenlearning something and recalling it will befilled with all kinds of different events. Thismakes it very difficult to be sure that anyforgetting which takes place is the result ofdecay rather than a consequence of theintervening events.
  89. 89. Trace Decay Theory• Support for the idea that forgetting fromshort-term memory might be the result ofdecay over time came from research carriedout by Brown (1958) in the United Kingdom,and Peterson and Peterson (1959) in theUnited States.• The technique they developed has becomeknown as the Brown-Peterson task.
  90. 90. Key Study: Peterson and Peterson(1959) – Duration of STM• Aim: They wanted to test their hypothesis thatinformation was held in the STM for onlyaround 20 seconds, after that it disappears ifrehearsal is prevented. Therefore aiming toprove that the duration of the STM is onlyaround 20 seconds. Also, to investigate ifinformation is lost from STM through decay.
  91. 91. • Method: Participants were presented withsets of trigrams (nonsense syllables in sets ofthree, e.g. BCM) which they were then askedto recall in order after a delay of 3, 6, 9, 12, 15and 18 seconds. An experimental method wasused: The IV was the time delay, and the DVwas the number of trigrams recalled.
  92. 92. • Participants were given an interference task ofcounting backwards in threes from a randomthree-digit number to prevent rehearsal(known as the Brown-Peterson technique).• Recall had to be 100% accurate and in thecorrect order in order for it to count ascorrectly recalled.
  93. 93. • 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 18seconds suggesting that the duration of the STMis not much more than 18 seconds.
  94. 94. • Conclusion: The memory trace in the STM hasjust about disappeared after 18 seconds.Information held in the STM is quickly lostwithout rehearsal.• This supports the hypothesis that the duration ofthe STM is limited to approximately 20 seconds.• They also concluded that this is evidence that theSTM is distinct from the LTM as the LTM has amuch longer duration (i.e. the results alsosupport the multi-store model).
  95. 95. Trace Decay Theory• Peterson and Peterson (1959) explained thisrapid loss in terms of trace decay. The memorytrace fades over time until it disappearscompletely. At this point, information isforgotten.
  96. 96. Displacement from Short TermMemory (STM)• Displacement seeks to explain forgetting inshort term memory, and suggests it’s due to alack of availability.• The short-term memory store in Atkinson &Shiffrins (1968) model of memory wasassumed to have certain characteristics,including a limited capacity, and if informationwas not rehearsed, it would be forgotten.
  97. 97. Displacement from Short TermMemory (STM)• Displacement theory provides a very simpleexplanation of forgetting. Because of its limitedcapacity, suggested by Miller to be 7+/- 2 items,STM can only hold small amounts of information.• When STM is full, new information displacesor pushes out’ old information and takes itsplace.• The old information which is displaced isforgotten in STM.
  98. 98. Displacement from Short TermMemory (STM)• It was also assumed that the information thathad been in the short-term store for thelongest was the first to be displaced by newinformation, similar to the way in which boxesmight fail off the end of a conveyor belt - asnew boxes are put on one end, the boxeswhich have been on the conveyor belt thelongest drop off the end.
  99. 99. Displacement from Short TermMemory (STM)• Support for the view that displacement wasresponsible for the loss of information fromshort-term memory came from studies using thefree-recall method.• A typical study would use the followingprocedure: participants listen to a list of wordsread out a steady rate, usually two seconds perword; they are then asked to recall as many ofwords as possible. They are free to recall thewords in any order, hence the term free recall.
  100. 100. Displacement from Short TermMemory (STM)• The findings from studies using free recall arefairly reliable and they produce similar resultson each occasion. If you take each item in thelist and calculate the probability ofparticipants recalling it (by averaging recall ofthe word over all participants) and plot thisagainst the items position in the list, it resultsin the serial position curve (Figure 1)
  101. 101. Simplified representation of the serialposition curve for immediate recall
  102. 102. Displacement from Short TermMemory (STM)• Good recall of items at the beginning of the list isreferred to as the primacy effect and good recallif items at the end of the list are referred to asthe recency effect.• T he displacement theory of forgetting fromshort-term memory can explain the recencyeffect quite easily. The last few words that werepresented in the list have not yet been displacedfrom short-term memory and so are available forrecall.
  103. 103. Displacement from Short TermMemory (STM)• The primacy effect can be explained usingAtkinson & Shiffrins (1968) multi-store modelwhich proposes that information is transferredinto long-term memory by means of rehearsal.• The first words in the list are rehearsed morefrequently because at the time they arepresented they do not have to compete withother words for the limited capacity of the short-term store.
  104. 104. Displacement from Short TermMemory (STM)• This means that words early in the list aremore likely to be transferred to long-termmemory. So the primacy effect reflects itemsthat are available for recall from long-termmemory.• However, words in the middle of the list usedto be in short term memory until they werepushed out - or displaced by the words at theend of the list.
  105. 105. Interference (LTM)• Interference theory states that forgettingoccurs because memories interfere with anddisrupt one another, in other words forgettingoccurs because of interference from othermemories (Baddeley, 1999).
  106. 106. Interference (LTM)• 1. Proactive interference (pro=forward)occurs when a person cannot remember newinformation because it has been confusedwith old information.• 2. Retroactive interference (retro=backward)occurs when you cannot remember oldinformation because new information hasinterfered with it.
  107. 107. Interference (LTM)• Previous learning can sometimes interferewith new learning (e.g. difficulties we havewith foreign currency when travellingabroad).• Also new learning can sometimes causeconfusion with previous learning. (StartingFrench may affect our memory of previouslylearned Spanish vocabulary).
  108. 108. Interference• Interference is thought to be more likely tooccur where the memories are similar, forexample: confusing old and new telephonenumbers.• Students who study similar subjects at thesame time often experience interference.Starting French may affect our memory ofpreviously learned Spanish vocabulary.
  109. 109. Interference (LTM)• In the short term memory interference canoccur in the form of distractions so that wedon’t get the chance to process theinformation properly in the first place. (e.g.someone using a loud drill just outside thedoor of the classroom.)
  110. 110. Lack of consolidation (LTM)• The previous accounts of forgetting havefocused primarily on psychological evidence,but memory also relies on biologicalprocesses. For example, we can define amemory trace as:• some permanent alteration of the brainsubstrate in order to represent some aspectof a past experience.
  111. 111. Lack of consolidation (LTM)• When we take in new information, a certainamount of time is necessary for changes tothe nervous system to take place – theconsolidation process – so that it is properlyrecorded.• During this period information is moved fromshort term memory to the more permanentlong term memory.
  112. 112. Lack of consolidation (LTM)• The brain consists of a vast number of cellscalled neurons, connected to each other bysynapses. Synapses enable chemicals to bepassed from one neuron to another. Thesechemicals, called neurotransmitters, caneither inhibit or stimulate the performance ofneurons.
  113. 113. Lack of consolidation (LTM)• So if you can imagine a network of neurons allconnected via synapses, there will be a pattern ofstimulation and inhibition. It has been suggestedthat this pattern of inhibition and stimulation canbe used as a basis for storing information.• This process of modifying neurons in order formnew permanent memories is referred to asconsolidation (Parkin, 1993).
  114. 114. Lack of consolidation (LTM)• There is evidence that the consolidation processis impaired if there is damage to thehippocampus.• In 1953, HM had brain surgery to treat hisepilepsy, which had become extremely severe.The surgery removed parts of his brain anddestroyed the hippocampus, and although itrelieved his epilepsy, it left him with a range ofmemory problems.• Although his STM functioned well, he was unableto process information into LTM.
  115. 115. Lack of consolidation (LTM)• The main problem experienced by HM is hisinability to remember and learn new things.This inability to form new memories isreferred to as anterograde amnesia.• However, of interest in our understanding ofthe duration of the process of consolidation isHMs memory for events before his surgery.
  116. 116. Lack of consolidation (LTM)• In general, his memory for events before thesurgery remains intact, but he does have somememory loss for events which occurred in thetwo years leading up to surgery.
  117. 117. Lack of consolidation (LTM)• Pinel (1993) suggests that this challenges Hebbs(1949) idea that the process of consolidationtakes approximately 30 minutes. The fact thatHMs memory is disrupted for the two-yearperiod leading up to the surgery indicates thatthe process of consolidation continues for anumber of years.• Finally, aging can also impair our ability toconsolidate information.
  118. 118. Retrieval failure theory (LTM)• Retrieval failure is where the information is inlong term memory, but cannot be accessed.• Such information is said to be available (i.e. itis still stored) but not accessible (i.e. it cannotbe retrieved).• It cannot be accessed because the retrievalcues are not present.
  119. 119. Retrieval failure theory (LTM)• When we store a new memory we also storeinformation about the situation and these areknown as retrieval cues. When we come into thesame situation again, these retrieval cues cantrigger 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.
  120. 120. Retrieval failure theory (LTM)• Tulving (1974) argued that information would bemore readily retrieved if the cues present whenthe information was encoded were also presentwhen its retrieval is required.• For example, if you proposed to your partnerwhen a certain song was playing on the radio, youwill be more likely to remember the details of theproposal when you hear the same songagain. The song is a retrieval cue - it was presentwhen the information was encoded andretrieved.
  121. 121. Retrieval failure theory (LTM)• Tulving suggested that information about thephysical surroundings (external context) andabout the physical or psychological state of thelearner (internal context) is stored at the sametime as information is learned.• Reinstating the state or context makes recalleasier by providing relevant information, whileretrieval failure occurs when appropriate cues arenot present. For example, when we are in adifferent context (i.e. situation) or state.
  122. 122. Context (external) DependentForgetting• Retrieval cues may be based on context-thesetting or situation in which information isencoded and retrieved.• Evidence indicates that retrieval is more likelywhen the context at encoding matches thecontext at retrieval.• Examples include a particular room, drivingalong a motorway, a certain group of people, arainy day and so on.
  123. 123. Context (external) DependentForgetting• You may have experienced the effect ofcontext on memory if you have ever visited aplace where you once lived (or an old school).• Often such as visit helps people recall lots ofexperiences about the time they spent therewhich they did not realize were stored in theirmemory.
  124. 124. State (internal) dependent cues• The basic idea behind state-dependent retrieval isthat memory will be best when a personsphysical or psychological state is similar atencoding and retrieval.• For example, if someone tells you a joke onSaturday night after a few drinks, youll be morelikely to remember it when youre in a similarstate - at a later date after a few moredrinks. Stone cold sober on Monday morning,youll be more likely to forget the joke.
  125. 125. Context (external) DependentForgetting• State Retrieval clues may be based on state-the physical or psychological state of theperson when information is encoded andretrieved.• For example, a person may be alert, tired,happy, sad, drunk or sober when theinformation was encoded. They will be morelikely to retrieve the information when theyare in a similar state.
  126. 126. Context (external) DependentForgetting• People tend to remember material betterwhen there is a match between their mood atlearning and at retrieval.• The effects are stronger when the participantsare in a positive mood than a negative mood.• They are also greater when people try toremember events having personal relevance.
  127. 127. Measures of retentionMeasures of retention. Memories may be retrieved in threeways.• 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 werelearned– paired associate recall: recall of a second item based on a cuesupplied by a first item• recognition: identification of previously learnedinformation (as, for example from a number of answerchoices in a multiple-choice test)• reconstruction: rebuilding of a scenario from certainremembered details
  128. 128. Amnesia• is the inability to remember events from the pastbecause of a psychological trauma ( psychogenicamnesia) or a physiological trauma ( organic amnesia),such as brain damage resulting from a blow to thehead. The memory loss is usually limited to a specificperiod.• Retrograde amnesia is the inability to rememberhappenings that preceded the traumatic eventproducing the amnesia.• Anterograde amnesia is the inability to rememberhappenings that occur after a traumatic event.
  129. 129. Amnesia• People sometimes forget things because theyfind them too unpleasant to think about.• Such an occurrence is called motivatedforgetting.• Sigmund Freud attributed many memoryfailures, particularly involving painfulchildhood experiences, to repression (theprocess of keeping disturbing thoughts orfeelings relegated to the unconscious).
  130. 130. Amnesia• The repressed material can sometimes berecalled through free association or hypnosis.• The recovery of supposedly repressedmemories, such as those of childhood sexualabuse, is controversial.
  131. 131. Biological Substrates in Memory• Although much information exists on theconnection between memory and biology, it isfar from complete.• At the neuron level, a deficiency of theneurotransmitter acetylcholine is a factor inthe dementia known as Alzheimers disease(administration of the neurotransmitter hasslowed the diseases progress but notprevented it).
  132. 132. • Reduced levels of the neurotransmitterglutamate have also been associated with thedisorder.• Serotonin, another neurotransmitter, is alsothought to be important in memory functioning.• Eric Kandel and James Schwartz, in a study of seasnails, found that serotonin is released as theylearn.• At the structural level, damage to thehippocampus, part of the limbic system, hasbeen associated with memory difficulties.