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STM capacity
5-9 items
STM coding
acoustic
STM duration
18 secs
LTM capacity
unlimited
LTM coding
semantic
LTM duration
up to a lifetime
Alan Baddeley (1966) study
a study that supports the idea that information is coded differently in different memory stores - STM and LTM
method: 4 groups shown acoustically and semantically (dis)similar words and asked to recall in the same order
results: when recalling immediately (STM) people did worse on acoustically similar and when recalling after 20mins they did worse on semantically similar words
Evaluating Baddeley (1966)
strength: identified 2 memory stores coding differently
strength: supports MSM
limitation: participant variables not accounted for
limitation: artificial stimuli
Joseph Jacobs (1987)
a study to measure digit span (and STM capacity)
method: starting at 3 digits read to participant and recalled in same order, the nom of digits increases until participant gets order wrong
results: mean digit span = 9.3 and mean letter span = 7.3
evaluating Jacobs (1987)
strength: replicated confirming validity
George Miller (1956)
research on STM capacity and chunking
results: observed things in 7s so thought capacity was 7 ±2 and thought we can chunk around 5 things together
evaluating Miller (1956)
limitation: overestimated STM capacity as 2001 study by Cohen though capacity was 4 ± 1
Peterson and Peterson (1959)
investigate the duration of STM
method: given a 3 digit number and consonant syllable and counted backwards then asked to recall the syllable in 3 sec pauses
results:
3 sec recall = 80%
18 sec recall = 3%
duration of STM is 18secs
evaluating Peterson and Peterson (1959)
limitation: artificial meaning
Harry Bahrick (1975)
investigate the duration of LTM
method: studied under 400 American between 17-74, asking them about yearbook people (through photo recognition and free recall)
results:
within 15 years of graduation - photo rec = 90% free recall = 60%
within 48 years of graduation - photo rec = 70% free recall = 30%
LTM can last up to a lifetime for some material
evaluating Bahrick (1975)
strength: high external validity (meaningful memories)
limitation: cultural bias (all American participants)
MSM: sensory register to STM
Attention
MSM: STM to LTM
prolonged rehearsal
MSM: LTM to STM
retrieval
MSM: LTM to STM
maintenance rehearsal
MSM: STM → out of memory
recall/retrieval
Sensory register coding
iconic: visual
echoic: acoustic
sensory register capacity
very high
sensory register duration
very brief - less than 0.5 secs
who proposed the MSM
Richard Atkinson and Richard Shiffin (1968-1971)
evaluating MSM
strength: research support shows STM and LTM coding is different (Baddeley 1966)
C/A: lack external validity as it uses artificial stimuli
limitation: More than one STM store/componant - Tim Shallice and Elizabeth Warrington (1970) studied KF who had bad acoustic recall but great visual recall of digits given to him = STM has more than one component
limitation: elaborative rehearsal = better quality than quantity of rehearsal can also transfer information into the LTM meaning there is more than one way (Fergus Craik and Michael Watkins 1973)
limitation: too oversimplified as it fails to show different parts of LTM - episodic, semantic, procedural
Case of HM
brain surgery to solve his epilepsy and had his hippocampus removed (central memory function)
he couldn’t form long term memories but very good STM span (so supports the MSM)
what are the types of LTM
episodic, semantic and procedural
episodic memory
our ability to recall specific memories throughout our life
time stamped (certain point in time that the memory was made)
a conscious effort must be made to retrieve the memory
semantic memory
our shared knowledge about the world
not time stamped (not a certain point when the memory was made)
Tulving says its less vulnerable to distortion and forgetting
procedural memory
memory for skills or actions
not time stamped (not a certain point when the memory was made)
no need to consciously think about how to do a skill/action
evaluating the types of LTM
strength: clinical evidence - HM and Clive Wearing left them unable to remember episodic memories, but recall semantic and procedural ones
C/A: lack of control of extraneous variables - researcher had no way of previously knowing the person’s memory failures
limitation: conflicting research finding linking LTM to parts of the brain (Buckner and Peterson 1996) but their research has been challenged before (eg. Tulving 1994)
strength: real world application - understanding types of LTM means psychologists can help people with memory problems (eg. older people can remember past episodic memories, but not recent ones)
limitation: separation of episodic and semantic memories - Tulving considered episodic memory being a category of semantic memory as research showed people with amnesia have good semantic but bad episodic memory (but a study showed people with Alzheimer’s could form new episodic memories but not remember old ones)
who introduced the idea of different types of LTM
Endel Tulving (1985)
Randy Buckner and Steven Peterson (1996)
created evidence against types of LTM
results: semantic memory is located on the left side of the prefrontal cortex and episodic memory is on the right side
what components does the WMM contain
central executive, phonological loop, visuospatial sketchpad, episodic buffer
phonological loop components
phonological store: stores the words you hear
articulatory process: allows maintenance rehearsal
visuospatial sketchpad components
visual cache: stores visual data
inner scribe: arrangement of objects in the visual field
phonological loop coding
acoustic
visuospatial sketchpad coding
visual
phonological loop capacity
2 seconds worth worth of what you can say
visuospatial sketchpad capacity
3 or 4 objects
episodic buffer
temporary store for information
integrates information by other stores
maintains a sense of time sequencing (records when events are happening)
central executive
supervisory role
monitors incoming data
focuses and divides our attention
allocates subsystems to tasks
doesn’t store information
episodic buffer capacity
4 chunks - very limited
central executive capacity
very limited processing capacity
evaluating WMM
strength: clinical evidence - case study of KF (good visual - VSS but bad acoustic - phonological loop) supports the existence of sparate visual and acoustic memory stores
C/A: unclear whether KF had other cognitive impairments/ other pre-exsisting damage to his memory or the trauma from the motorcycle injury might have affected his cognitive performance
strength: dual performance can’t take place for tasks in competition for the same subsystem - Badeley (1975) proved 2 tasks fighting for the same subsystem doesn’t work
C/A: the studies used to support this are lab experiments with artificial stimuli
limitation: nature of central executive is unclear - some psychologists believe it may have separate subcomponents and is unsatisfactory (challenging integrity of the model)
Cases of HM and Clive Wearing
both had brain damage from operation (HM) and infection (Clive Wearing) and underwent surgery leaving them unable to remember episodic memories, but recall semantic and procedural ones
Case of KF
got into a motorcycle accident and had brain surgery leaving him with poor STM for auditory information but normal STM for visual information
defintion of interference
forgetting because one memory blocks another, causing one or both memories to be distorted or forgotten
proactive interference
when an older memory blocks a newer one
retroactive interference
when a newer memory blocks an older one
mcGeoch and McDonald (1931)
studied retroactive interference by changing the similarity of 2 materials
method: participants are told a list of words then split 6 groups and told another list with different similarities to the original (including control group)
results: the worst recall was for the list with the most similar words to the original list showing interference is strongest when information is similar
2 reasons why similarity affects recall
proactive interference - older information makes it harder to store newer and similar information
retroactive interference - new information overwrites the older information making it harder recall both sets of information due to the similarity of them
evaluating interference
strength: real world interference (Baddeley and Hitch rugby player evidence = valid argument)
C/A: interference in everyday situation is unusual because sets of information aren’t as similar in everyday vs in a lab (lab studies are controlled therefore information is manipulated to be more similar)
strength: support from drug studies (Coenen and Luijtelaar 1997) proves drugs can help if info is learnt first, but increases interference for info learnt after the drug is taken
limitation: interference is temporary and can be overcome by using cues (Tulving and Psotka 1971)
limitation: validity issues and lab experiments = artificial stimuli
Baddeley and Hitch (1977)
method: asked rugby players the names of teams they played during the season but some players missed games (due to injury)
results: the players that played the most games had the most interference and recalled the least team names
Anton Coenen and Gilles Van Luijtelaar (1997)
method: split participants into a drug taking (diazepam) and placebo group and gave them all a list of words which they had to later recall
results: the recall of the words learnt before the drug was taken was stronger than the placebo group but was extremely poor when the words were learnt after the drug was taken, meaning the drug helped recall when information was learnt first
Endel Tulving and Joseph Psotka (1971)
seeing the effect that cues have on interference and memory
method: gave participants lists of words in categories (categories not told to the participants at first)
results: free recall of words started at 70% and then gradually dropped, but when cues and category names were introduced it rose back to 70% throughout showing that interference causes temporary loss of information but cues can retrieve them
cue
a trigger of information that allows us to access a memory
accessibility vs availability
all stored LTM are accessible but cues help them become available
Encoding Specificity Principle (ESP)
discovered by Endel Tulving (1983)
states a cue will help with memory retrieval if it is present at encoding and retrieval
context dependent forgetting
recall depends on an external cue (eg. environment, weather, smells)
Godden and Baddeley (1975)
sees the effects of context-dependant forgetting
method: 4 conditions in which people would learn information on land/water and then recall it on land/water
results: recall was 40% lower in non-matching situations
state dependant forgetting
recall depends on internal cues (eg. mood, drunkness)
Carter and Cassaday (1998)
sees the effect of state dependant forgetting
method: 4 conditions in which people are told information on/off drug and recall it on/off the drug
results: memory was significantly worse in the mismatched conditions
evaluating retrieval failure
strength: real world application = retrieval cues can help stop forgetting everyday (eg. if you loose something, your likely to return to the environment in which you last remember having it/learning it)
strength: research support - Godden and Baddeley (land vs water) and Carter and Cassaday (drug vs no drug)
C/A: Godden and Baddeley (1997) was extreme environments, and everyday life the environment change isn’t as dramatic meaning less forgetting as environments are often similar
limitation: context effects may depend on the type of memory being tested - Godden and Baddeley was replicated as a recognition test instead of a recall test (participants were asked if they recognised a word instead of retrieving it themselves) and performance in all conditions was the same meaning retrieval failure is a limited explanation for when a person has to recall information instead of recognising it
limitation: problems with ESP - if a cue isn’t encoded at the time of learning, having it present at the time of retrieval has no effect
Post event discussion (PED)
when there is more than one witness to an incident and they are allowed to discuss what they witnessed, leading to possible influences on others accounts
Elizabeth Loftus and John Palmer (1974)
studied the impact of misleading questions on EWT
method: 45 students watched car accident and were asked a critical question in which the description of the colliding (of the cars) was changed (eg. bumped, smashed, hit)
results: the estimated speed for the verb with the leats power (hit) was 31.8mph but for the most powerful (smashed) it was 40.5mph (and some recalled seeing broken glass that was never there)
response bias
the wording of the leading question doesn’t affect our memory, but impacts how we answer the question
substitution
the wording of a leading question changes our memory of an event
effect that leading questions have on EWT
response bias and substitution
Fiona Gabbert et al (2003)
research on post event discussion
method: participants paired up and watched the same crime filmed from different points of view (each pair saw a different angle of the crime) and then discussed what they saw before completing a recall test
results: 71% reported mistakes from the crime that weren’t in the video but in the control group this was 0%
memory contamination
when witnesses discusses events with each other, the testimonies become altered or distorted because they combine (mis) information from others
memory conformity
witnesses go along with each other during discussion due to NSI or ISI but their memories remain unchanged
2 ways in which PED affects EWT
memory contamination and memory conformity
why does PED affect EWT
source monitoring theory and conformity theory
source monitoring theory/ source confusion
memories of an event are distorted and witnesses will recall information without the memory of whether it was from their memory or from someone else’s account
conformity theory
memories aren’t distorted by PED but witnesses go along with others due to NSI or ISI
evaluating misleading information on EWT
strength: real world application (criminal legal system) and psychologists can improve the legal system but preventing legal convictions based on EWT
C/A: lab setting experiments, more stressful and traumatic living the experience than watching it and therefore EWT would be different in a lab vs courtroom
limitation: EWT is more accurate for some aspects of events than others - Sutherland and Hayne (2001) proved recall of main details are accurate but less accurate for peripheral ones due to where our attention goes to
limitation: memory conformity is evidence that PED alters EWT because if PED changes the EWT then people haven’t fully conformed to others
limitation: demand characteristics in lab experiment - dont want to let researcher down so they guess an answer
how does anxiety impact recall
anxiety creates a physiological arousal and stops us focusing on important cues so our recall is worse
what is weapon focus
when the introduction of a weapon increases anxiety of a situation making our recall worse
Craig Johnson and William Scott (1976)
saw the effect that anxiety has on recall
method: low and high anxiety condition, low = a man walked past the waiting room holding a pen with grease on it, high = participants listened to a heated argument and then a man walked past holding a blooding knife
results: identifying the man from 50 pictures in low = 49% but in high only 33%
tunnel theory
we have better memory for central events (eg. weapon focus) and bad recall for much else
John Yuille and Judith Cutshall (1986)
studied a shooting in a gun shop in candy in which the owner shot a thief (21 witnesses and 13 took part in the study)
method: 13 witnesses were interviewed for 4-5 months after the event and recollections were compared to original police interviews done right after the shooting, they were also asked to rate their anxiety at the time
results: witnesses with the highest anxiety had the most accurate account (88% accuracy) showing that anxiety has a more positive effect on recall
inverted - U theory
Yerkes - Dodson Law says memory becomes more accurate as anxiety increases only to a certain point, but more anxiety after this point will result in a lower recall
evaluation of anxiety on EWT
strength: evidence exists to support that anxiety has a negative effect on recall - Valentine and Mesout 2009
C/A: Yuille and Cutshall experiment proves anxiety has a positive effect on recall
limitation: inverted U theory is too simplistic as it disregards the cognitive and behaviour components and focuses only on the physiological components of anxiety - cognitive (the way we think in stressful situation) is also important for the accuracy of EWT
limitation: unusualness vs anxiety - Johnson and Scott experiment may have tested people confusion on seeing the weapon instead of their anxiety to seeing the weapon - supported by Kerri Pickel 1998
Valentine and Mesout 2009
measured anxiety using a heart rate measure in high and low anxiety groups
method: participants went to London Dungeon and were scared by different actors and asked to recall which actor scared them (some raised the anxiety level higher than others)
results: heart rate showed that more scary actors creating more anxiety clearly disrupted participant’s ability to recall the actor - 17% more than other actors - 71%
Kerri Pickel 1998
repeated Johnson and Scott study to see unusualness vs anxiety
method: 4 conditions in which a man held 4 items (getting more unusual from scissors to a raw chicken)
results: EWT was poorer in higher unusualness conditions therefore Johnson and Scott lacks validity as it could have been measuring a person’s reaction to the unusualness of seeing a bloody knife
who proposed the cognitive interview
Ronald Fisher and Edward Geiselman (1992)
what is a cognitive interview
a method of interviewing eyewitness to help them retrieve more accurate memories of an event
what techniques are used (in order) for cognitive interviews
report everything
reinstate the conetxt
reverse the order
change perspective
what and why do we use the 1st technique of a cognitive interview
report everything - witnesses are encouraged to explain every single detail of an event (even if it seems unimportant) because everything may trigger important memories
what and why do we use the 2nd technique of a cognitive interview
reinstate the context - witnesses are encouraged to return to the scene of the event in their minds and imagine the exact environment (feeling, setting) as this relates to context dependant forgetting
what and why do we use the 3rd technique of a cognitive interview
reverse the order - witnesses should recall events in a different oder to how they actually occurred to prevent people reporting their expectations of how events occurred and prevent dishonesty as changing the order will make lies harder to include
what and why do we use the 4th technique of a cognitive interview
change perspective - witnesses are encouraged to recall the events for another’s perspective to disrupt the effect of the schema on recall (stops expectations centred around a specific environment)
who proposed enhanced cognitive interviews
Fisher et al (1987)
what is included in enhanced cognitive interviews
focus on establishing a good relationship with witness - more comforting
Making eye contact when necessary
witnesses are encouraged to speak more slowly
interviewer instructed to use open questions to avoid leading the witness
evaluating cognitive interviews
strength: research support - Gunther Kohnken et al 1999 to prove Cognitive interviews are successful in helping a witness recall information that is stored but not immediately accessible
C/A: Kohnken also found an increase in inaccurate information given in (E)CI meaning that information from (E)CI is more likely to include unreliable data as well as reliable data
strength: police forces use a ‘pick and mix’ approach to CI which makes it more flexible and individuals can develop their own approaches based off the (E)CI structure
C/A: It is hard to tell the effectiveness of different approaches to find the overall reliability of (E)CI for interviewing witnesses
limitation: not all elements of CI are equally effective (report everything and reinstate the context) - Milne and Bull (2002)
limitation: CI is time-consuming making it unrealistic for law enforcement to use in practise, making officers reluctant to using it as it takes more time and training, it might be better to use a few key elements of a CI instead of the entire structure of it
Gunter Kohnken et al (1999)
the effect cognitive interviews have on witness’ memory of an event
method: combined data from 55 studies comparing (E)CI to standard police interview
results: there is 41% increase in more accurate information given in (E)CI compared to standard interviews, with only 4 studies showing no difference between the information given
Milne and Bull (2002)
While they found that CI were more useful than standard police interviews, they found that a combination of report everything and reinstate the context produced the best recall than any other elements and combinations of them