Memory Studies
- Created by: Kerry
- 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
Evaluation:
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
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
Evaluation:
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
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
Bahrick et al - EVALUATION
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
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
Baddely - EVALUATION
Evaluation:
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
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
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
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
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
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
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
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
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
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
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
MISLEADING INFORMATION & EWT - Loftus and Palmer
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
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
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
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
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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