Memory

• Coding:

  • coding - how information is changed to be stored
  • Baddeley: gave word lists to four groups of participants to remember:
  • Group 1 (acoustically similar) - words sounded similar
  • Group 2 (acoustically dissimilar) - words sounded different
  • Group 3 (semantically similar) - words with similar meanings
  • Group 4 (semantically dissimilar) words with different meanings
  • immediate recall for short-term memory was worse for acoustically similar words
  • recall after 20 mins for long-term memory was worse for semantically similar words
• Evaluation for coding:

  Strengths: identified a clear difference in the coding of memory, acoustically in STM and semantically in LTM

  Limitations: artificial stimuli means the study has limited ecological validity
• Capacity: Jacob's digit span

  • capacity - how much can be stored in memory
  • Jacob's: digit span
  • researcher read out four digits, recalled by participants in the correct order
  • if recalled in correct order, researcher would increase digits until no longer recalled in order, indicating digit span
  • mean span was 9.3 items and 7.3 letters
• Capacity: Miller's chunking

  • capacity - how much can be stored in memory
  • Miller's: chunking
  • made observations of everyday practise
  • noted things came in 7's (7 notes in a scale, 7 days in a week)
  • suggested STM is about 7 items +/- 2
  • we do this by chunking, grouping sets of digits or letters into units or chunks
• Evaluation for capacity:

  Strengths: despite the possibility of confounding variables, Jacob's study has been replicated, suggesting validity

  Limitations: Cowan reviewed Miller's research and concluded that the capacity of STM is only 4 +/- 1, suggesting Miller overestimated the capacity
• Duration: Peterson and Peterson duration of STM

  • duration - how long information can be stored
  • 24 participants in 8 trials given a consonant syllable to remember
  • also given a 3 digit number to count back from until asked to stop in order to prevent any mental rehearsal of the consonant syllable
  • after 3 seconds, average recall was 80%
  • after 18 seconds, average recall was 3%
  • suggests STM duration is 18 seconds unless we rehearse information
• Duration: Bahrick duration of LTM

  • duration - how long information can be stored
  • 392 participants aged between 17-74 showed yearbook
  • recall tested through photo-recognition and free recall of names
  • 15 years of graduation were 90% accurate on photo-recognition
  • 48 years of graduation were 70% accurate on photo-recognition
  • 15 years of graduation were 60% accurate on free recall
  • 48 years of graduation were 30% accurate on free recall
  • suggests LTM may last up to a lifetime for some material
• Evaluation for duration:

  Strengths: Bahrick's research has high external validity as he investigated meaningful memories, Shepard found that recall rates were lower on meaningless memories

  Limitations: Peterson and Peterson's research lacks external validity as recalling consonant syllables doesn't reflect everyday memory activities
• The multi-store model of memory: Atkinson and Shiffrin

  • assumes there are three separate memory stores and information is transferred between these stores in a linear sequence
  • an environmental stimuli enters the sensory register for 1/2 a second, if payed attention within 18 seconds enters STM, if not becomes spontaneous decay
  • we can keep information in our STM as long as it is rehearsed, if so it passes into a LTM which has unlimited duration
• Strengths of the Multi-store model of memory

  • Baddeley: found we tend to mix up acoustically similar words in our STM and semantically similar words in our LTM, showing our STM and LTM are separate memory stores
• Limitations of the Multi-store model of memory

  • Shallice and Warrington: studied client KF suffering from amnesia, his STM for digits was poor when read aloud to him but his recall was better when he read the digits himself, suggesting MSM is wrong in claiming there is just one STM store processing different types of information
  • Watkins: found that the type of rehearsal was more important than the amount, elaborative rehearsal is needed for long-term storage whereby you link information to your existing knowledge, meaning information can be transferred without prolonged rehearsal
• Types of LTM: Tulving

  • episodic memory - personal events (lesson at school yesterday)
  • semantic memory - knowledge of the world (what an orange tastes like)
  • procedural memory - knowledge of how to do something (driving a car, becomes second nature)
• Strengths of types of LTM:

  • clinical evidence, Clive Wearing and HM impaired their episodic memory due to brain damage, but semantic and procedural memories were unaffected (Clive could still play piano), supports Tulving's view that there are different memory stores in LTM, one store can be damaged but other stores are unaffected
  • real world application to Belleville: found as people get older its their episodic memory that weakens, therefore devised an intervention to improve episodic memories in older people, trained group performed better on a test of episodic memory than a control group
• Limitations of types of LTM:

  • idiographic research lacks generalisability
  • Peterson and Buckner: conflicting neuroimaging evidence, found that semantic memory is on the left of the prefrontal cortex, whereas the episodic is on the right, other studies have found the memory stores the other way around, therefore there is poor agreement on the location of each type
• The working memory model: Baddeley and Hitch

  • central executive - 'supervisory role' and allocates 'slave systems' tasks, limited storage and capacity
  • phonological loop - deals with auditory information, phonological store stores words you hear, articulatory process used to rehearse verbal information, 2 second capacity
  • visuo-spatial sketchpad - stores visual and spatial information, visual cache stores visual data, inner cache records the arrangement of objects in the visual field
  • episodic buffer: general storage space, integrates with LTM, capacity of 4 chunks
• Strength of the working memory model:

  • Shallice and Warrington: case study KF, found after injury had bad STM for sound but could still process visual information, which supports the separate visual and acoustic memory stores
• Limitation of the working memory model:

  • Baddeley: said the central executive may consist of separate subcomponents, therefore there's a lack of clarity over the nature of the central executive
• Explanations for forgetting: Interference

  Types of interference:

  • proactive - when an old memory interferes with a new memory
  • retroactive - when a new memory interferes with an old memory
  • McGeoch and McDonald: studied retroactive interference
  • participants had to learn a list of 10 words until they could remember them with 100% accuracy
  • 6 groups of different types of new lists: synonyms, antonyms, unrelated words, consonant syllables, 3 digit numbers, no new list (control group)
  • found when asked to recall the original list, the synonym group had the worst recall
• Strengths of explanations for forgetting: interference

  • McGeough and McDonald: research shows interference was strongest when the memories are similar
  • Baddeley and Hitch: ecological validity, they asked rugby players to recall names of teams they had played against, players who played the most games had poor recall
• Limitations of explanations for forgetting: interference

  • Tulving and Psotka: gave participants lists of words organised into categories, one list at a time, (participants didn't know the categories) recall averaged about 70% for the first list then got worse as they learnt new lists, once told the categories recall rose to 70%, therefore showing interference causes a temporary loss of memory
• Explanations for forgetting: Retrieval failure: context-dependent

  • Context-depending forgetting - recall depends on external cue
  • Godden and Baddeley:
  • studied divers who work underwater to see if training on land helped or hindered their work underwater
  • created a four conditions:
  • learn on land-recall on land, learn on land-recall underwater
  • learn underwater-recall underwater, learn underwater-recall on land
  • recall was 40% lower in the non-matched conditions
  • concluded that external cues in learning were different to recall environment, causing retrieval failure
• Explanations for forgetting: Retrieval failure: state-dependent

  • State-dependent forgetting - recall depends on internal cue
  • Carter and Cassaday:
  • gave antihistamine drugs, a mild sedative, and a word list to participants, creating an internal physiological state different from the normal state of being alert and properly awake
  • created four conditions:
  • learn on drug - recall on drug
  • learn on drug - recall off drug
  • learn off drug - recall off drug
  • learn off drug - recall on drug
  • concluded that internal cues in learning were different to recall state, causing retrieval failure
• Strengths for forgetting: retrieval failure

  • Baddeley: ecological validity to walking into a room and forgetting what you wanted, then leaving the room and remembering
  • Eysenck and Keane: argue that retrieval failure is perhaps the main reason for forgetting
  • highly controlled lab conditions increase reliability
• Limitations for forgetting: retrieval failure

  • Golden and Baddeley: replicated their underwater experiment but used recognition instead of recall, when recognition was tested there was no context-dependent effect and the performance was the same in all four conditions, therefore only a partial explanation as it only applies to recall rather than recognition
• Factors affecting the accuracy of eyewitness testimony: anxiety negative

  • anxiety has a negative effect on recall (weapons focus):
  • Johnson and Scott: lab study
  • participants seated in a room in a low anxiety condition, heard a conversation then saw a man walk past carrying a greasy pen
  • other participants seated in a room in a high anxiety condition, heard an argument and breaking glass, then saw a man walk past carrying a bloody knife
  • later identified the man from 50 photos, 49% identified the man with the pen, 33% for the man with the knife
• Factors affecting the accuracy of eyewitness testimony: anxiety positive

  • anxiety has a positive effect on recall
  • Yuille and Cutshall: conducted a study of an actual shooting in a gun shop in Canada
  • used 13 of the witnesses as participants, interviewed after the incident and compared to the original police interviews
  • accuracy determined by by the number of details reported
  • also asked to rate how stressed they had felt at the time
  • found little change in recall
  • 88% recall for higher stress, 75% for lower stress
• Strengths of factors affecting the accuracy of eyewitness testimony:

  • Christianson and Hübinette: interviewed 58 witnesses to actual back robberies in Sweden, researchers assume those involved would experience the most anxiety, found 75% accuracy in all witnesses, confirming anxiety doesn't reduce the accuracy of recall
• Limitations of factors affecting the accuracy of eyewitness testimony:

  • Pickel: conducted an experiment using scissors, a handgun, a wallet and a raw chicken, found that eyewitness accuracy was significantly poorer in unusual conditions, suggesting that weapon focus may just be due to being surprised rather than scared
• Improving the accuracy of eyewitness testimony: cognitive interview

  Fisher and Gieselman: could improve police interviews

  • report everything - witnesses encouraged to include every detail of the event as it may trigger important events
  • reinstate the context - witnesses should return to the original crime scene and imagine the environment and their emotions, helps with context-dependent forgetting
  • reverse order - events recalled in a different order will prevent people reporting their expectations and as well as dishonesty
  • change perspective - recall incident from other people's perspectives
• Improving the accuracy of eyewitness testimony: enhanced cognitive interview

  • Fisher: developed some additional element of the cognitive interview to focus on the social dynamics of a situation
  • interviewer must understand when to establish eye contact
  • must also reduce eyewitness anxiety, minimise distractions, get the witness to speak slowly and ask open-ended questions
• Strengths of improving the accuracy of eyewitness testimony: CI and ECI

  • Köhnken: meta-analysis combing data from 55 studies comparing the CI and ECI to a standard police interview, the CI gave 41% more accurate information than the standard interview, therefore is an effective technique in helping witnesses recall information
• Limitations of improving the accuracy of eyewitness testimony: CI and ECI

  • Milne and Bull: found that each technique used alone produced more information than the standard police interview, also found using 'report everything' and 'reinstate context' produced better recall than any other combination, therefore some elements are more useful
  • police officers may be reluctant to use the CI because it takes more time and training than a standard police interview, a rapport must be established for relaxation and therefore may be an unrealistic method