Memory Studies

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  • Created on: 24-11-13 11:41

Jacobs - CAPACITY of STM

Method - Presented a series of numbers or letters to participants which they had to recall in the correct order 

Findings - An average participant could recall 9 numbers but 7 letters 

Conclusion - Capacity of STM is 7 +/- 2 items 


More recent research finds similar/consistent results so suppports Jacobs findings         Real life applications - number plates are no longer than 7 numbers 

STM capacity may be affected by HOW information is presented e.g. visually                         Low in mundane realism                                                                                                     Lacks Historical validity                                                                                                       Participant variables - individual differences e.g. educational level, age 

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Peterson & Peterson - DURATION of STM

Method - 24 university students, nonsense TRIGRAMS - avoiding vowels, P's had to remember the trigram whilst counting aloud backwards in 3's from a number they were given, retention intervals of: 3,6,9,12,15,18 seconds - had to write down trigram, two practice trials and eight trials per participant - used repeated measures                                                                         

Findings - as the retention interval increases the % of p's with correct recall decreased from 80% to 10% 

Conclusion - accuracy of STM decreases with time 


  High levels of control - p's had to count aloud                                           Used standardised procedures - increases reliability as can be retested          Used repeated measures - participant variables are decreased                           Used all university students                                                                         Participant variables - boredom effects, trigram holding meaning                         Lacking in ecological validity and mundane realism 

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Bahrick et al - DURATION of LTM

Method - Year book study, 374 P's aged 17-74, 3 conditions:                                - Free recall condition - yearbook of pictures and had to name faces                    - Name recognition - Names of schoolmates & random names - had to identify schoolmates                                                                                                - Matching condition - had to match names with faces    

Findings - P's that had left school up to 34 years ago had 90% accuracy on matching and name recognition                                                                      P's that had left school 48 years ago had 80% accuracy                                      Free recall condition steadily declined 

Conclusion - Recall can be very accurate over a long period of time, invention of the term vLTM to describe this 

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Bahrick et al - EVALUATION


High in mundane realism                                                                                 Large sample size - covers wide age range, generalisable results, representative, high population validity                                                                                 Higher control over participant effects due to large sample - anomalies                   Used standardised procedures - replicability 

Other factors may decrease accuracy e.g. size of year group, popularity               Lack of control over extraneous variables - people could still be in contact 

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Baddely - ENCODING of LTM & STM

Method - Young service men p's, given one of 4 sets of words to recall in correct order, 4 sets of words were:                                                                           2 study groups - words semantically similar, words acoustically similar                    2 control groups - words semantically different, words acoustically different            For STM they had to recall words immediately after presentation                          For LTM they had to recall words after a longer interval 

Findings -                                                                                                   STM - p's made more mistakes on words that were acoustically similar                   LTM - p's more likely to confuse words of similar meaning

Conclusion -                                                                                              STM - encoded acoustically                                                                          LTM - encoded semantically  

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High control - same words used and neutral words                                              Independent groups used - reduces order effects like boredem and practice effects 

Lacks population validity as sample isnt representative of the population                 Used independent groups so results could be affected by participant variables         Lacks mundane realism 

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MSM evaluation - STRENGTHS

Brain scans:                                                                                                 Found: LTM tasks activate the hippocampus, STM tasks activate the preforental cortex - LTM and STM are seperate stores like the MSM assumes

This is strong supporting evidence as scientific and factual

Glantzer & Cunitz or Murdock                                                                         Found: Rehearsal aids recall as words at the start of the list are recalled at a higher %, STM and LTM are seperate stores 

This is strong supporting evidence as lab experiment - high control of extraneous variables - strong and replicable results 

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MSM evaluation - WEAKNESSES

Spiers et al - amnesiacs study                                                                     Found: LTM has sub stores - Procedural, Semantic and Episodic, therefore LTM is not a single store like the MSM assumes - the MSM is too simplistic 

This is weak contradicting evidence as was a study of people who's brains are already 'broken' 

Shallice & Warrington - KF                                                                           Found: KF could only recall visually presented information and not acoustically presented information, shows STM isnt a single store as MSM suggests - MSM is too simplistic 

This evidence is weak as is a case study so may not be generaliasable or reliable as lacks replicability 

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WMM evaluation - STRENGTHS

Case study of KF - STM works independently of LTM and shows evidence of the separate visual and auditory systems as assumed

Empirical research - Baddely, CE cant allocate 2 tasks to the same component at the same time - supports that STM has sub components 

Empirical research is reliable as standardised procedures used, strengthens support for the WMM 

Real life applications - Park et al - found schizophrenics WMM's have decreased capacity compared to normal peoples, used to diagnose schizophrenia - suggests that WMM is valid 

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WMM evaluation - WEAKNESSES

KF case study - weakens support as difficult to generalise as his brain was damaged, lacks replicability as cant give someone brain damage 

WMM isnt a complete explanation of memory - central executive is more complex than WMM suggests, WMM could have sub stores and not be a single store as predicted by the WMM 

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ANXIETY & EWT - Yuille and Cutshall

Method - studied bystanders in a robbery of a Vancouver gun store where the criminal was shot by the store owner, police interviewed 21 witnesses, researchers interviewed 13 again 5 months later

Found: anxiety IMPROVES recall as those upset tended to be more accurate

Strengths -  High ecological validity as in a natural setting                                   Real levels of emotion, retention and attention - real life applications and high in mundane realism                                                                                         Ethical - not all witnesses took part so shows there was a right to withdraw, already witnessed the crime so no psychological harm caused 

Weaknesses - difficult to generalise as unique event                                         Small sample size from one town - lacks population validity                                   Unethical - asked leading questions, deception, had to relive the crime so distress    Data was turned from qualitative to quantitative so may have been bias in interpreting the results                                                                                 Lack of control over extraneous variables as natural experiment 

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ANXIETY & EWT - Christianson and Hubinette

Method - looked at EWT from 22 bank robberies in stockholm over 1 year, 58/110 EWT                                                                                                        Found - self reported anxiety had no effect on accuracy, feeling personally threatened suring a crime increases anxiety, bank workers directly involved were more accurate 

Concluded - accuracy of EWT ISNT AFFECTED by anxiety 

Strengths - high ecological validity as natural experiment                                     High in mundane realism as real life event                                                       Reduced demand characteristics - p's didnt know they were being studied              Studied over a period of a year - more population validity as more witnesses          Ethical - not put under stress as had already witnessed the crime 

Weaknesses - witnesses with complete or memory of the event took part so figures could have been inflated                                                                           Lack of control of extraneous variables as in natural environment                        Lack of control over participant variables as natural environment 

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ANXIETY & EWT - Loftus et al

Method - discussion was heard in an adjoining room, used 2 conditions:                   Low anxiety - man emerged with greasy pen                                                       High anciety - more heated discussion, man emerged with bloody knife                   P's had to identify man from 50 photos, LA - 49%, HA - 33% accurate 

Found - weapon focus effect, anxiety DECREASED accuracy

Strengths - lab experiment so high control of extraneous variables                   Used standardised procedures so increases replicability and reliability                    Ethical - had informed consent as knew they were being studied 

Weaknesses - lab experiment so lacks ecological validity and mundane realism        Demand characteristics - p's knew they were being studied                                Independent groups - affected by individual differences and participant variables   Unethical - could cause psychological stress in high anxiety condition        

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AGE & EWT - Yarmey

Method - stopped 651 adults in public places, woman spoke to them for 15 seconds, interval of 2 minutes then asked what the woman looked like

Findings - young people (18-29) and middle aged (30-44) were more confident than older people (45-65) in their accuracy, however no significant differences in accuracy

Conclusion - age has NO EFFECT on accuracy however confidence levels are higher in middle aged and younger people 

Strengths - high in ecological validity, reduced demand characteristics                   Large sample size - more generalisable and representative, less affected by anomalie  Ethical - debriefed and given chance to withdraw data - no psychological harm       Used standardised procedures - replicability and reliability 

Weaknesses - lack of control over extraneous variables - distractions                   Participant variables & individual differences                                                     Ethical issues - deception, lack of informed consent 

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AGE & EWT - Parker and Carranza

Method - showed slides of mock crime to primary school kids and college students, asked to identify perpetrators from photos

Findings - Primary school children were less accurate - more likely to make incorrect identifications than college students 

Conclusion - suggests that accuracy of EWT IMPROVES with age 

Strengths - used standardised procedures so could be replicated                          Ethical - sought informed consent        

Weaknesses - Ethical - psychological harm to young children - cant give informed consent                                                                                                  Low in mundane realism                                                                              Lacks ecological validity                                                                             Demand characteristics 

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AGE & EWT - Anastasi and Rhodes

Method - 3 age groups (18-25, 33-45, 55-78), shown 24 pictures - 8 faces from each age group, followed by a short filler task, shown 48 pictures and asked to identify the 24 originally shown

Findings - People are more accurate at identifying people from their own age group - own age bias, older people are less accurate in general 

Conclusion - accuracy of EWT DECREASES with age 

Strengths - used standardised procedures - replicability                                   Ethical - informed consent as lab study 

Weaknesses - Lacks ecological validity                                                           Lack of control over participant variables and individual differences 

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1st study method - 45 university students in 5 groups of 9, 7 videos of traffic incidents, asked leading questions, 1 critical - how fast was the car going when it: hit, smashed, collided, bumped or contacted, changed order - reduce order/boredom effects

Findings - group with the word smashed estimated the highest speed, group with contacted estimated lowest 

Conclusion - Leading questions can have a significant impact on how information is stored or retrieved 

2nd study method - investigate if storage or retrieval, different 150 p's - 50 control group, 50 smashed, 50 hit, week later asked if their was broken glass

Findings - those with smashed were more likely to recall broken glass (there was none)

Conclusion - misleading information affects the way information is initially stored 

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Loftus and Palmer - EVALUATION

Strengths - Used standardised procedures - replicability                                     High control of extraneous variables as a lab study                                            Reduced order/boredom effects by showing videos in different order 

Weaknesses - Only used uni students - young and inexperienced drivers so less likley to be able to judge speed                                                                   Lacks population validity - less representative/generalisable                                 Low in mundane realism - less anxiety than real car accident                               Some extraneous variables lack of control - participant variables as independent groups 

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The Cognitive Interview

More structure than original police interview 

4 components - 

Report everything - every detail, even if seems irrelevant                                   Mental reinstatement of original context - mentally recreate scene of crime             Changing the order - alternative starting points, vary route through memory            Changing the perspective - asked to describe other witness/criminal viewpoint 

Enhanced cognitive interview - 

Interviewers are encouraged to build a rapport with EW - less pressure, relaxed     Focused retrieval - Witnesses encouraged to focus concentration, make the extra effort to remember 

Weaknesses - isnt a standardised procedure for CI as techniques arent applied consistently by all police departments                                                             Individual differences - some people may be better at using the CI than others 

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EVALUATION of CI - Kohnken

Supports the claim that it increases the accuracy of EWT                                    Method - meta analysis of 53 studies                                                             Conclusion - CI increases accuracy of EWT as found 34% increase in statements compared to standard interview 

Weaknesses - mostly lab studies - lacks ecological validity                                 Lack real life application - lab studies                                                             Low in mundane realism - no/low anxiety in lab                                                   Student volunteers - age bias, lacks population validity so not representative or generalisable to general public                                                                         

These criticisms may weaken the overall support for the CI as the CI effectiveness may be limited to experimental settings 

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EVALUATION of CI - Stein and Memon

Supports the claim that the CI increases accuracy of EWT                                   Method - studied brazilian cleaners who witnessed a who witnessed an abduction, shown videos to identify the criminals                                                             Conclusion - the CI is effective in real life situations, they got more richer and detailed forensic information than from a standard police interview - CI increases accuracy of EWT 

Strengths - shows real life applications of CI                                                      High in ecological validty and mundane realism 

Weaknesses - Pratical issues - time consuming                                                 Ethical issues - could unearth trauma - psychological harm                                 Requires cooperating interviewees                                                                   Still a risk of leading questions 

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