memory Flashcards
capacity of stm
limited
7 +/- 2 pieces of info
evaluation of capacity of stm studies
miller 1956:
- looks at wide range of research reliable
- didnt conduct his own research so couldnt see if he got the same results
- theory of stm supported by research
- cowan 2001 found that stm has 4 chunks, not 7 like miller suggested
jacobs:
- digit span test
- read out 4 digits, then recall them
- conducted his own experiments
- own data = mostly reliable
- limited data (women of certain age group)
- conducted experiment on letters aswell = 2 sets of data
duration of stm study procedure + evaluation
peterson and peterson:
- 24 psychology students
- experimenter read out triagram to ptp, then was told to count back in 3s or 4s
- result : as delay between hearing triagram increased, ability to recall decreases.
- conclusion: duration of approximately 18 seconds.
- nonsense triagrams lacks mundane realism
- students tend to be more intelligent than the general public
how is info coded in stm
acoustically
coding in stm study
baddeley 1966:
- 4 groups, list of words acoustically/semantically, similar/dissimilar
- asked to recall in correct order
- when asked to recall immediately, they tended to do worse with acoustically similar words
- artificial stimuli lacks mundane realism
capacity of ltm
unlimited
duration of ltm study procedure + evaluation
bahrick et al:
- 400 ptps, 17-74
- free recall, photo recognition, name recognition
- tested with 15 years = 90% accurate visual + verbal recognition
- after 48 years, recall declined to 80% name recall, 70% face recall
- free recall less good
- recognition better than recall which means we need prompts to remember stuff
- not lab exp = ecological validity
- ptps may have rehearsed beforehand
- high external validity
how is info coded in ltm
semantically
coding in ltm study and evaluation
baddeley 1966:
- 4 groups, list of words acoustically/semantically, similar/dissimilar
- asked to recall in correct order
- when asked to recall words 20 mins later, they did worse with semantically similar words
- controlled environment
- poor hearing tested by Baddeley, everyone given a hearing test
- artificial stimuli lacks mundane realism
what is the msm
presents how memory is stored, transferred between stores, retrieved, forgotten etc
msm description
3 stores: sensory register, ltm, stm
- sensory register = haptic, echoic, iconic. large capacity, duration of less than half a second. info will only pass to stm if we pay attention
- ltm = unlimited capacity, duration of 47 years.
- stm = 7 +/- 2 pieces of info capacity, duration of approximately 18 seconds
study to support msm
- HM supports idea that stm and ltm are seperate stores. 1996: had epilepsy and went under surgery to remove hippocampus and temporal lobes. alleviated epilepsy, left him with ltm problems, was unable to form new memories. couldn’t transfer new information into ltm. could remember people he had known long ago but forgot new people.
study against msm
shallice and warrington:
- kf, motorbiike accident
- could still add memories to ltm even though stm was damaged
- msm cant explain this
- kf had poor stm recall for auditory stimuli, increasing accurate recall for visual stimuli
- kf able to differentiate and recall both verbal & non verbal sounds, suggest there’s diff types of stm
general evaluation of msm
- oversimplified: not enough info
- studies to support lack mundane realism e.g digit and letters instead of a shopping list. msm may not be a valid model of how memory works irl
- prolonged rehearsal isnt needed to transfer to ltm, the more you rehearse, more likely to transfer to ltm (prolonged rehearsal). craik and watkins (1973) found that the type of rehearsal is more important than the amount. elaborative rehearsal is needed for lt store to age. suggests that msm doesnt fully explain ltm
- acknowledges qualitative differences between stm and ltm, shows them as seperate stores. stm = acoustically, ltm = semantically
- msm portrays accurate view on differences between ltm and stm. baddeley found that we mix up acoustically similar words in stm and semantically similar in ltm. shows they are diff
wmm description
- suggest stm is made up of central executive, phonological loop, visuospacial sketchpad and episodic buffer
- ce: overall control, responsible for lots of tasks
- pl: ‘inner voice’ limited capacity, deals with auditory info
- vss: used when planning a spatial task
- eb: limited capacity, integrates info from other areas
evidence to support wmm
- shallice and warrington: kf, supports wmm cause findings show that kf had poor stm recall for auditory stimuli, increased recall for visual stimuli, suggests components of memory which processes auditory and visual stimuli are seperate
evaluation of study to support wmm
- unclear whether kf had other cognitive impairments which may have affected his performance on memory tasks e.g injury caused by motorcycle accident. trauma may have affected his cognitive performance. challenges evidence from clinical studies of people with brain injuries that may have affected many different systems
general evaluation of wmm
- studies of dual task performance support separate existance of vss. baddeley et al’s ptps carried out a visual and verbal tasks at the same time. performance on each was similar to when they carried out the tasks seperately. when tasks were both visual and verbal, performance declined on both drastically cause both visual tasks compete for the same subsystem (vss) whereas there is no competition when performing a visual verbal task together. shows a seperate subsystem that process visual input.
- central executive not exactly defined. process is vague, ce may be made up of sub components
- lack of explanation draws doubt about accuracy. ce needs to be more clearly specified than just being simply ‘attention’ e.g psychologist believe the ce may consist of seperate sub components, ce = unsatisfactory component
3 types of ltm
procedural
semantic
episodic
procedural ltm
- for performance of certain actions
- unconscious recall
research for procedural ltm
hm and corkin:
- hm taught new motor skill
- gradually improved as days went on
- tested days later, did well but no recollection of doing task before
episodic ltm
- personal memories, includes details of event, context etc
- have to make effort to recall
research for episodic ltm
clive wearing and hm:
- both had great difficulty recalling pasts
- semantic memories relatively unaffected
- e.g: still knew meanings of words
- procedural memory intact too suggests there are different memory stores in ltm, one can be damaged and others unaffected
semantic ltm
- memories for meaning and understanding things
- general knowledge
- less vulnerable to distortion
research for semantic ltm
tulving 1989:
- injected radioactive gold so he would track blood flow in brain
- scanned brain whilst he thought about historical facts/ childhood experiences
- blood flow in the parietal and occipital lobes increased when thinking bout historical stuff
explanations for forgetting
interference: one memory disturbs ability to recall another. may result in forgetting/distortion
proactive: previously learnt info interferes with new info
retroactive: new info interferes with previously learnt info
research to support interference theory
mcgeoch and mcdonald 1931:
- ptps learnt list of adjectives until they could recall them perfectly
- some ptps spent 10 mins resting whilst others learnt new info (varied in similarity to old)
- the more similar the new material was to original, recall of original test declined
evaluation of study to support interference theory
mcgeoch and mcdonald 1931:
- shows that the more similar the later material is, the greater the interference
- low ecological validity: lab experiment, not representative of real life
- lacks mundane realism: not real life activity
- different settings need consideration
cue dependant forgetting
forgetting due to the lack of cues
context dependent forgetting
based on environmental/ external cues
state dependent forgetting
based on yourself/ internal cues
study and procedure for context dependent forgetting
godden and baddeley:
- tested divers’ recall and learning on land and in water (matching and mismatched conditions)
- e.g learning on land, recall in water or learning on land, recall on land too
- recall better (50%) when learning and recall contexts were the same. 40% forgot when contexts were different
- same environment = higher recall
study and procedure for state dependent forgetting
carter and cassaday 1998:
- gave ptps antihistamines to make them drowsy
- learnt words and passages (matched and mismatched conditions)
- e.g learning when drowsy, recall when sober, learning when drowsy, recall when drowsy
- significantly worse recall on mismatched conditions
evaluation of study for context dependent forgetting
- high mundane realism, eye witness testimonies
- lacks generalisability, focus only on divers = not generalised to all cases of context cues
evaluation of study for state dependent forgetting
- high reliability= lab experiment, controlled conditions
- supported by goodwin et al: gave alcohol to ptps, same findings
- doesn’t take into account extraneous variables
factors that affect accuracy of eye witness testimony
- leading questions/ misleading info
- post event discussion
- anxiety
- cognitive interview
what is a leading question
question that suggests an answer
what can go wrong in the stages of retrieval if leading questions are asked
encoding: encoded into ltm, may be partial or distorted - crimes happen quickly, night time etc
retain : retains info for long period of time. memories may be lost or modified during retention along with other activities
retrieval: retrieves info from storage. presence/absence of appropriate retrieval cues may affect accuracy
evidence to support negative effect of leading questions
loftus and palmer:
aim - effect of leading questions on ewt
research method - lab experiment
design - independent groups
iv - verb used: smashed, collided, bumped, hit, contacted
dv - speed estimate in mph
sample - 45 students
findings - smashed: 40.8mph, collided: 39.3mph, bumped: 38.1mph, hit: 34.0mph, contacted: 31.8mph
conclusions: leading questions can alter people’s memories
why do leading questions affect ewt
response bias: suggests wording has no effect on ptps memories, just influences how they answer. when you use violent verb ‘smashed’, estimate speed increased
substitution: loftus and palmer 1974 conducted a 2nd experiment to support this. wording changes ptps memory, shown in study as ptps who heard ‘smashed’ recalled seeing broken glass when there wasn’t
strengths and weaknesses of study for leading questions effect on ewt
- high control: results due to IV and not other confounding variable
- low ecological validity: doesn’t have same emotional impact
- only students used, not representative of entire population
- when watching a real car crash, there is more context, ptps had been cued to watch the video. in real life, car crashes are unexpected
- ewt is more accurate for some aspects of an event than others. sunderland and hayne 2001, showed ptps clips, ptps were more focused on central details of event than peripheral
what is post event discussion
when more than one witness discusses a crime they have seen. testimonies become contaminated cause they combine information from own memory with others
two theories related to p.e.d
source monitoring theory
conformity theory
what is the source monitoring theory
when ptps can recall info but not where its from
what is the conformity theory
ewt changes answer in order to be liked or cause they actually believe the others
evidence to support post event discussion
gabbert et al:
set up ptps in pairs, each pair watched a video of the crime but on their own. same crime, 2 different point of views. 1 ptp saw elements of the crime that the other person couldn’t have seen. then they paired up and discussed. 71% ptps mistakenly recalled aspects of event they couldn’t have seen in the video but picked up from the discussion. in control group (people who didn’t have ped), 0% incorrectly recalled
oklahoma bombing 1995:
1 witness claimed to see murderer. initally no one else could describe him but later on they also claimed to recall him. eventually eye witness 1 realised they were wrong
bodner et al:
found that ped reduced if ptps were warned of effects of testimony. recall more accurate for ptps who were warned
evaluation of studies to support post event discussion
gabbert et al:
- unable to conclude why distortion occurs, could be poor memory, unable to distinguish between what they’ve seen or heard.
- however, could be due to social pressure (conformity). cannot conclude which theory determined the results.
- uncertainty makes study unreliable .
- same for oklahoma bombing
bodner et al:
- shows real life effect
- in real life, police make eyewitness aware of effects of post event discussion.
- reduces memory conformity
physical and emotional effects of anxiety
physical:
- increased heart rate, breathing rate etc
emotional:
- worried thoughts, tension
how does anxiety affect recall
increases alertness
improves memory
evidence to support positive effect of anxiety on eye witness testimony
yuille and cutshall 1986:
- showed witnesses gun shooting outside a gun shop in canada
- thief shot 6 times and died
- 13 witnesses re-interviewed 5 months later. recall was very accurate, leading questions had no effect on accuracy
christianson and hubinette 1993:
- 110 witnesses of 22 real life bank robberies were interviewed some time after robberies. victims suprisngly accurate recall of robber’s clothing and behaviour, still accurate 15 months later
- although they have no control over post event discussion over 15 months. lack of confounding variables
evidence to reject positive effect of anxiety on eye witness testimony
valentine and mesout:
- researcher used objective measure (heart rate) to divide ptps into high-low anxiety groups
- anxiety clearly disrupted ptps ability to recall details of actor in london dungeon’s labyrinth.
- suggest anxiety has negative effect on ewt immediately after event
johnson and scott:
- in room 1, ptps saw man emerge with pen
- in room 2, ptps saw man emerge with penknife covered in blood
- when asked to identify person from 50 pics, 49% of room and 33% of room 2 correctly identified him
- suggests anxiety’s negative effect on ewt
evaluation of studies to support eye witness testimony
yuille and cutshall:
- conducted in real life, high ecological validity but isn’t very controlled (extraneous variables)
- field study, behaviour was spontaneous and natural
what is the cognitive interview + stages
- method of interviewing eye witnesses
stages of interview are as follows:
- report everything, even small insignificant details as they can trigger recall of larger events by acting as a ‘cue’
- reinstate the context, recall the weather, location, mood of day etc. prevents context dependent forgetting by reminding eye witness on external cues at the time of the event
- change perspective, recall events from perspective of victim or persecutor
- reverse order, recall events in different order, other than chronological, reduces eyewitnesses ability to lie
evidence to support cognitive interview
fisher et al 1989:
- 16 police detectives from florida were asked to record some interviews using standard interview techniques.
- after this 7 police detectives were trained to implement the cognitive interview technique whilst 9 used the standard police interview technique
- all detectives had a minimum of 5 years experience
- over 7 months, the interviews were recorded and analysed
- trained detectives obtained 47% more info from interviewees after training
- gained 63% more info than their untrained counterparts
evaluation of evidence to support cognitive interview
fisher et all:
- The study showed strong support for using the cognitive interview technique in the practical field. There was also no loss of accuracy of information along with increased information obtained
- high ecological validity as the study was conducted on actual police detectives.
- ethical as the participants had been given full information about the study beforehand.
- demand characteristics as the participants were paid for their participation; they may have acted in a way which they thought was desirable for the researcher.
- ethnocentric as the study was conducted on police detectives in a Floridian county.
- lack of generalisability due to small sample size.
general evaluation of cognitive interview
- time consuming and requires training in order to conduct interview e.g kebbel and wagstaff argued that a few hours of training is insufficient to train them for the cognitive interview
- the cognitive interview also increases the recall
of incorrect information by 61%, as suggested by Kohnken et al (1999), appears counterintuitive
