Memory

• Capacity in short-term memory - Jacobs

  • Participants were to remember and recall a set of numbers which would gradually increase in length
  • The average span for digits was 9.3 items and 7.3 letters. For every participant, digit span was always between 5 and 9
  • The capacity of short term memory was around 7 digits
• Coding in short-term memory - Conrad

  • Participants were to remember and recall 2 sets of 6 letters, 1 set that sounded similar, 1 set that sounded dissimilar
  • More mistakes were made when the letters sounded similar than different
  • Therefore we must hear the sounds in our head, therefore information is stored acoustically
• Duration in short-term memory - Peterson and Peterson

  • Participants were to remember trigrams that were presented auditorily. After hearing the trigram, participants were to count backwards in threes for a set amount of time to prevent rehearsal, and then asked to recall the trigram.
  • More mistakes were made the longer the retention interval. The performance score dropped to below 5% when the interval was 18 seconds. More recent research suggest this to be more like 20-30 seconds in duration
  • The duration of short term memory is up to 30 seconds
• Coding in long term memory - Baddeley

  • Participants were asked to recall 4 lists of words and then recall them after a period of time: Set A - acoustically similar; Set B - acoustically dissimilar; Set C - semantically similar; Set D - semantically dissimilar
  • Participants were better at Set C or Set D
  • Long term memory uses semantic coding
• Capacity of long term memory - Wagenaar

  • Conducted research on himself across 6 years where he recorded one or two significant personal events on a daily basis collecting a total of 2402 items. He described the event in ‘who, what, where, when’ details. He tested his memory with cued recall tasks - when told where he remembered who, what and when etc
  • Recall on events rather than dates was easier to remember. The what cue was more effective and the when cue the least effective
  • Long term memory capacity is absolutely huge, if not unlimited
• Duration of long term memory - Bahrick et al

  • Participants aged 17-74 were asked to either: have free recall as many names of their former classmates as possible; asked to recognise former classmates in a set of 50 photos; a name recognition test
  • Visual recognition was best as it remembered the most people
  • The duration of long term memory is very long, potentially a life-time
• Clinical evidence for different types of long term memory - Clive Wearing

  • Clive suffered from a severe form of amnesia which damaged his hippocampus
  • He lacks the ability to form new memories, however he can still understand the world around him
  • There are many different types of long term memory
• Neuroimaging evidence for different types of long term memory - Tulving et al

  • Participants were to perform various memory tasks while their brains were being scanned using a PET scanner
  • Episodic and semantic memories were both recalled from the prefrontal cortex. The left prefrontal cortex was involved in remembering semantic information and episodic memories were recalled from the right prefrontal cortex
  • Different parts of long term memory are controlled by different physical parts of the brain
• Clinical evidence for the working memory model - Shallice and Warrington on KF

  • KF suffered from a brain injury which affected his memory. Shallice and Warrington investigated his memory when he read a task or listened to a task
  • His immediate recall of letters/digits was better when he read than listened. He had poor short term memory auditorily but normal visual
  • This supports the existence of separate visual and acoustic memory stores
• Dual task performance - Baddeley et al

  • Participants carried out visual and verbal tasks
  • Visual and verbal tasks performed at the same time were done perfectly, but when two visual or two verbal tasks were completed at the same time, the performance declined
  • This supports and shows how there are separate subsystems for visual and acoustic information
• Research into interference theory - Schmidt et al

  • 200 participants aged 11-79 were given a map of their neighbourhood where street names were replaced with numbers. They were asked to recall the correct street names, and relevant personal details (how many times they moved house/how often they visit the neighbourhood)
  • Positive association between the number of times participants and moved house outside the neighbourhood and the number of street names forgotten
• The effect of similarity - McGeogh and McDonald

  • Participants learnt a list of 10 words until they could remember them with 100% accuracy, then learnt a new set of words, then had to recall the original set of words
  • When participants were given no interference material, they did better and recalled more items than participants who were given another list of synonyms
  • This suggests that interference is worse when memories are similar therefore, forgetting is more likely if the information is similar
• Encoding specificity principal - Tulving

  • Research was made into retrieval failure
  • When memory is coded, it is linked to the context/state of that time which becomes a cue for retrieving the memory from long term memory
  • When the context of recall is similar to the context of coding, a memory is more likely to be retrieved. Forgetting occurs when cues are unavailable
• Evidence for retrieval failure - Carter and Cassidy

  • Participants learnt a list of words/passage of writing in 4 conditions: learn on drug and recall on drug; learn not on drug and recall on drug; learn on drug and recall not on drug; learn not on drug and recall not on drug
  • Recall was significantly worse when there was a mismatch between conditions at learning and recall
  • Shows that a lack of cues (state dependent cues in this case) can lead to forgetting. This supports Tulving's Encoding Specificity Principle
• Evidence for retrieval failure explanation - Godden and Baddeley

  • Divers learnt a list of words in 4 conditions: learn on land and recall on land; learn underwater and recall on land; learn on land and recall underwater; learn underwater and recall underwater
  • Accurate recall was 40% lower in the non-matching conditions
  • The external cues available at learning were different from the ones available at recall, which led to retrieval failure
• NAMED STUDY - Leading questions - Loftus and Palmer

  • Procedure
  • Exp 1 - 45 students were to watch several clips of car crashes and were then asked to estimate the speed of the car. There were 5 groups with the verb changing in each question: ‘About how fast were the cars going when they contacted/hit/bumped/collided/smashed each other
  • Exp 2 - 150 participants viewed the video of the car crash. 50 were asked with ‘smashed’, 50 were asked with ‘hit’ and a control group weren’t asked. A week later, they were questioned whether they saw any broken glass (there wasn’t any)
• NAMED STUDY - Leading questions - Loftus and Palmer

  Findings

  • Exp 1 - contacted: 32mph; smashed: 41mph (everything else in between)
  • Exp 2 - smashed: 32% said yes; hit: 14% said yes; control: 12% said yes
  • The wording of a question does change the actual memory a participant has of an event leading to remembering inaccurate accounts. This supports the occurrence of substitution
• NAMED STUDY - Anxiety negatively affecting eyewitness testimony - Johnson and Scott

  Procedure

  • Participants believed they were sat in a waiting room waiting for a lab experiment. They were asked to point out a picture of the man after:
  • Low-anxiety condition - casual conversation then a man carrying a pen walked past
  • High-anxiety condition - heated argument could be heard, accompanied by the sound of breaking glass, then a man walked past holding a bloodied knife
• NAMED STUDY - Anxiety negatively affecting eyewitness testimony - Johnson and Scott

  Findings and conclusions

  • 49% of people accurately picked out the pen-holding man; 33% of people accurately picked out the bloody-knife man
  • The tunnel theory of memory argues that people have enhanced memory for central events. Weapon focus as a result of anxiety can have this effect. Anxiety has a negative effect on recall. This may be because witnesses focus on the weapon, meaning that other details are recalled inaccurately
• Anxiety positively affecting eyewitness testimony - Yuille and Cutshall

  Procedure

  • Conducted a real-life shooting in a gun shop where the shop owner shot a thief dead. There were 21 witnesses, 13 of which agreed to take part. Interviews were conducted 4-5 months after and the recounts were compared to the initial police reports. They were also asked to rate how stressed they were out of 7 at the incident and if they had any emotional problems after
• Anxiety positively affecting eyewitness testimony - Yuille and Cutshall

  Findings and Conclusions

  • Witnesses were very accurate in their accounts after the 5 years apart from small details such as colour of items/age/height etc. Those who recounted having the highest levels of stress accurately recounted 88% of the details whereas, for the less stressed group, 75% of details were remembered
  • Suggests that anxiety does not have a detrimental effect on the accuracy of eyewitness memory in a real-world context, and may even enhance it
• Research support for cognitive interviews - Geiselman et al

  • Watch a film of violent crime and, after 48 hours, were interviewed by a policeman using: cognitive interview; standard interview; interviewing using hypnosis. The number of facts and errors were recorded
  • Correctly recalled facts for: cognitive interview - 41.2; hypnosis - 38.0; standard - 29.4. There was no significant difference in the number of errors in each condition
  • The cognitive interview leads to better memory of events, with witnesses able to recall more relevant information compared with a traditional interview method