Cognitive Flashcards
Capacity of STM - Millers Magic 7 (1956)
Capacity of STM - limited
Miller noticed in everyday practice that things come in sevens such as notes on a musical scale, days of the week, the deadly sins etc
He concluded that the capacity of the STM was about 7 items (plus or minus 2) and this could be increased by chunking - groups sets of digits/letters together into meaningful units
Capacity of STM - Jacob’s (1887) digit span test
Researcher reads 4 digits and increases by one each time until the ptp cannot correctly recall all of them. The final number of digits correctly recalled is their digit span.
On average ptps could recall 9.3 numbers and 7.3 letters in the correct order immediately after they were presented.
Strength of Jacob’s study - replicable
It’s an old study so may have lacked adequate controls such as confounding variables eg ptps being distracted. Despite this Jacob’s findings have been confirmed in later controlled studies eg Boop and Verhaeghen 2005) shows Jacob’s study is a valid measure of STM digits span.
Weakness of miler magic 7 - overestimates STM capacity
Jacob’s research does support millers however Cowan (2001) reviewed other research and concluded that the capacity of STM was only about 4 (plus or minus 1) chunks. This suggests that the lower end of Millers estimate (5 items) is more appropriate than 7 items.
Capacity of LTM
Potentially unlimited
Duration of STM
Limited duration - seconds. Info can be kept in for longer through rehearsal
Duration of STM - Peterson and Peterson (1959) Trigrams
24 psych students were given trigrams to recall and a 3 digit number to count backwards from in 3s or 4s to prevent rehearsal. The retention interval was varied - 3,6,9,12,15 or 18 seconds.
After 3 seconds the average recall was around 80% and after 18 seconds it was 3%. STM duration without rehearsal is up to 18 seconds.
Weakness of Peterson and Peterson study - uses meaningless stimuli
The recall of trigrams does not reflect meaningful everyday memory tasks so therefore the study lacks external validity.
Duration of LTM - Bahrick et al (1975) Yearbook photos
Ptps were 392 Americans aged between 17 and 74
1 - recognition test - 50 photos from high school yearbook
2 - free recall test - ptps listed names from their graduating class
Findings - recognition test - 90% accurate after 15yrs and 70% accurate after 48yrs
Free recall test - 60% accurate after 15yrs and 30% accurate after 48yrs
Free recall ability decreases with age to a large extent
Strength of Bahrick et al (1975) study - high external validity
Uses everyday meaningful memories eg peoples faces and names . When lab studies done with meaningless pictures to be remembered recall rates were lower - Stephenson 1967. Means that Bahrick et als findings reflect a more ‘real’ estimate of duration of LTM.
Coding in STM
Acoustically
Info is stored in memory in different forms depending on the memory store. The process of converting information between different forms is called coding.
Coding in LTM
Semantically
Coding in STM and LTM - Baddely (1966) acoustic and semantic
Gave different lists of words to four different groups of people
- acoustically similar (eg cat, cab, can) or dissimilar (eg pit, few, cow)
- semantically similar (eg great, large, huge) or dissimilar (eg good, huge, hot)
Immediate recall worse with acoustically similar words. STM is acoustic
After 20 mins worse with semantically similar words. LTM is semantic
Strength of Baddeleys study - used controlled conditions
Study had controls in place to prevent extraneous variables from confounding the results eg poor hearing - hearing test and only used people worth perfect scores. The experiment took place in controlled conditions in lab.
Limitation of Baddeleys study - used artificial stimuli
Words used had no personal meaning to ptps so tells us little about coding for everyday memory tasks. When processing more meaningful information people use semantic coding even for STM. Means the findings of this study have limited application.
MSM - Atkinson and Shiffre (1968)
The MSM describes how information flows through the memory system. Memory is made of three unitary stores that vary in encoding, duration and capacity.
MSM - Sensory register
All stimuli from the environment passes into the sensory register. It 5 memory stores one for each sense eg echoic - codes acoustically and iconic - is visual.
Coding - modality - specific, depends on the sense (visual in iconic, acoustic in echoic etc)
Duration - very brief, less than half a second
Capacity - very high
The sensory register holds an image for a few seconds while it is scanned to decide if attention should be paid and passed on through the system for further processing
MSM - transfer from SR to STM
Info passes further into memory only if attention is paid to it (attention is the key process)
MSM - STM
A limited capacity store of Temporay duration
- coding - acoustic
- duration - about 18 seconds unless info rehearsed
- capacity - between 5 and 9 (7 plus or minus 2) items before some forgetting occurs
MSM - transfer from STM to LTM
Maintenance rehearsal occurs when we repeat material to ourselves. We can keep info in STM as long as we rehearse it. If we rehearse it long enough it goes into LTM.
MSM - LTM
A permanent memory store
- coding - mostly semantic
- duration - potentially up to a lifetime
- capacity - potentially unlimited
MSM - retrieval from LTM
When we want to recall info from LTM it has to be transferred back to the STM by a process called retrieval
Limitation of MSM - evidence suggesting there is more than one store
Shallice and Warrington 1970 studied KF who suffered brain injuries after a motorcycle accident. His STM recall for digits was poor when he heard them but much better when he read them. He had trouble with verbal STM not visual STM. Other studies confirm there may be seperate STM stores for non-verbal sounds eg noises. So MSM is wrong to claim there is only one store of STM processing different types of information.
Support - Glanzer and Cunitz 1966 primary and recency effect
Words are better recalled from beginning - primary effect and end of a list - recency effect. In the primary effect words go to LTM. In recency effect - words are in STM and start of recall. Support for separate STM and LTM stores
Limitation of MSM - prolonged rehearsal is not needed for STM to LTM transfer
Craik and Watkins (1973) argued there are two types of rehearsal called maintenance and elaborative. Maintenance is the one described in the multistore model. but elaborative rehearsal is needed for long-term storage. This occurs e.g. when you link information to your existing knowledge or think about its meaning. This suggest that the multistore model does not explain how long term storage is achieved.
Strength of MSM - linear way - seoville and Milner (2006)
Case study of HM - he suffered from epilepsy and underwent brain surgery to remove part of his temporal lobes and hippocampus. It alleviated his epilepsy but left him of severe memory deficits although his IQ remained above average. he could not form long-term memories. this suggests hippocampus may function as a memory gateway memories must pass through before entailing permanent storage.
Types of LTM - episodic
It refers to ability to recall events from our lives like a diary of personal experiences. Eg what you had for breakfast this morning. They are complex memories as they are time stamped so you remember when they happened and how they relate in time. They involve several elements like people, places, objects and behaviours are woven into one memory. You have to make a conscious effort to recall them. Declarative
Research for episodic memory - clinical evidence
People who had brain damage to hippocampus and have memory deficits - Clive wearing and HM. Both had severely impaired episodic memory as a result of amnesia. Semantic memories were relatively unaffected as still knew meaning of words. HM could not recall stroking a dog an hour ago but would never need the concept of a dog explained to him. Procedural memory also intact as both knew how to tie shoelaces. Shows evidence of the seperate types. However there memories can’t be compared to how they were before the injury so can’t see how much worse it is - lack of control variables.
Types of LTM - semantic
Memories for meaning of the world and understanding eg like a dictionary. Contains knowledge of concepts and words eg animals. The memories are not time stamped eg we don’t remember when we first learnt about the film frozen. They are less personal than episodic memories and more about facts and knowledge we all share.
Research for semantic LTM - brain scan evidence Tulving
Brain scan evidence - tulving 1989 - injected himself with particles of radioactive gold to track brain blood flow in scanner when he was thinking of historical facts blood flow increased at back of brain but when thinking of childhood experiences blood flow increased at the front. Two different places for semantic and episodic memories shows there are different types.
Types of LTM - Procedural
Stores memories for actions and skills, memories of how we do things eg driving a car. Recall occurs without awareness or effort. These skills or actions become automatic with practice. Explaining a step by step procedure eg changing gear is hard because you do it without conscious recall.
Research for procedural LTM - corkin 1968 - HM
Studied HM with serious anterograde amnesia and was unable to store LTM. Taught new motor skills - tracing lines on a moving disc. Initially performance was poor but improved. Several days later retested and performed the same as previously even without recollection of doing task before - could form new procedural memories
WMM - Baddely and Hitch (1974)
WMM is a model of STM. It’s concerned with the ‘mental space’ that is active eg working on an arithemtic problem or playing chess or comprehending language etc
WMM - Central Executive (CE)
Allocates subsystems. Supervisory role- monitors incoming data, directs attention and allocates subsystems to tasks. It has a very limited storage capacity.
Coding is modality free = can take any type of coding
WWM - Phonological Loop (PL)
Consist of a phonological store and an articulatory process. PL deals with auditory information and preserves the order in which information arrives. Has a capacity of 2 seconds and is coded acoustically. It is subdivided into-
- phonological store - stores the words you hear
- articulatory process - allows maintenance rehearsal (repeating sounds to keep them in the WM while they are needed)
WMM - Visio-spatial sketchpad (VSS)
Stores visual and/or spatial information when required. Capacity is 3-4 objects and is coded visually. (Eg recalling how many windows your house has).
Logie (1995) subdivided the VSS into -
- visual cache - stores visual data
- inner scribe - records arrangement of objects in visual field
WMM - Episodic Buffer (EB)
Temporary storage of information. Added in 2000. Integrates visual, spatial, and verbal information from other stores. Maintains sense of time sequencing - recording events (episodes) that are happening. Links to LTM.
Coding = modality free
Capacity is limited to about 4 chunks
Strength of WMM - dual task studies
Studies of dual- task performance support the seperate existence of the VSS. Baddeley et al (1975) ptps found this was the same for two verbal tasks. This is because both visual tasks compete for the same subsystem ( VSS). That is no competition with a verbal and visual task. Therefore, there must be separate subsystem that processes visual input (VSS) and also a separate subsystem for verbal processes (PL).
Counter - these two studies are wholly controlled and used tasks that are unlike every day working memory tasks for example recalling random sequences of letters. This challenges the validity of the model because it is not certain that working memory operates this way in every day situations.
WMM - limitation is a lack of clarity over the central executive
Baddeley (2003) set the central executive was the most important but the least understood component of working memory. There must be more to the central executive than just being attention for example it is made up of separate subcomponents. Therefore, the central executive is an unsatisfactory component and this challenges the integrity of the model.
WWM - support from clinical evidence KF
Shallice and Warrington 1970 - case study of KF. After his brain injury, KF had poor STM ability for auditory info but could process visual info normally for example immediate recall of letters and digits was better when he read them (visual) than when they were read to him (acoustic). KF phonological loop was damaged but his visuo- spatial sketchpad was intact. This finding strongly supports the existence of separate visual and acoustic memory stores.
Counter - KF may have had other impairments which explained poor memory performance apart from damage to his phonological loop. This challenges evidence from clinical studies of brain injury.
Explanations of forgetting in LTM - interference
Interference - when two pieces of information disrupt each other. Forgetting occurs in the LTM because we can’t get access to memories even though they are available.
Explanations of forgetting in LTM - proactive interference (PI)
Occurs when an older memory disrupts a newer one eg a teacher learns many names in the past and can’t remember names of her current class.
Explanations of forgetting in the LTM - Retroactive interference (RI)
RI happens when a newer memory disrupts an older one eg a teacher learns many new names this year and can’t remember the names of her previous students.
Explanations for forgetting in LTM - interference is worse when memories are similar
This may be because -
- in PI previously stored information makes new information more difficult to store
- in RI new information overwrites previous memories which are similar
Explanations for forgetting in LTM - interference study to support McGeoch and McDonald (1931) Effects of similarity
Studied retroactive interference by changing the amount of similarity between two sets of material. Ptps were asked to learn a list of 10 words until they could remember them with 100% accuracy. They were then given a new list to learn. The new material varied in the degree in which it was similar to the old.
-group 1 - synonyms - words had similar meanings to originals
-group 2 - antonyms - words had opposite meanings to the originals
-group 3 - unrelated - words unrelated to the original ones
-group 4 - consonant syllables
-group 5 - three digit numbers
-group 6 - no new list - ptps just rested (control condition)
Findings and conclusions - performance depended on the nature of the second list. The most similar material (synonyms) produced the worst recall. This shows that the interference is strongest when memories are similar.
Explanations of forgetting LTM - interference - A03 - support for interference in real- world situations
Baddeley and Hitch (1977) asked rugby players to recall the names of teams they had played against during a rugby season. Players did not play the same number of games (injuries). Those who played most (more interference) had poorest recall. This shows that interference operates in some everyday situations increasing the validity of the theory.
Counter - interference in everyday situations is unusual because the necessary conditions are relatively rare eg similarity of memories/ learning doesn’t often occur. Therefore most everyday forgetting may be better explained by other theories (eg retrieval failure due to lack of cues)
Explanations of forgetting in LTM - interference - A03 - interference effects maybe overcome using cues - Tulving and Psotka (1971)
Gave ptps lists of words organised into categories (not told what they were). Recall of first list was 70% but fell with each new list (interference). When given a cued recall test (names of categories) recall rose again to 70%. This shows that interference causes a temporary loss of access to material still in LTM - not predicted by theory.
Explanations of forgetting in LTM - interference AO3 - strength - retroactive - postman
Used a lab experiment - ptps were split into two groups both had to remember a list of words eg cat-tree, jelly-moss. Experimental groups also had to learn another list of words where the second paired word was different eg cat-glass - control group not given second list. All ptps asked to recall words on first list. Results - recall of control group more accurate than experimental.
Counter- lacks ecological validity as task artificial so not real life situation so people may not behave the same so limited support as can’t be generalised.
Explanations for forgetting - retrieval failure - absence of cues
Lack of cues can cause retrieval failure. When information is initially placed in memory, associated cues are stored at the same time. If the cues are not available at the time of retrieval you might not access memories that are actually there.
Explanations for forgetting in LTM - retrieval failure - encoding specificity principle - Tulving 1983
Cues help retrieval if the same ones are present at both encoding - when we learn the material and at retrieval- when we are recalling it. If the cues available at encoding and retrieval are different (or if cues are entirely absent) there will be some forgetting.
Explanations for forgetting in LTM - retrieval failure - links between encoded cues and material to be remembered
Meaningful links - the cue ‘STM’ leads you to recall lots of material about short-term memory.
Not meaningful links -
- context-dependent forgetting - recall depends on external cue eg weather or a place
- state- dependent forgetting - recall depends on internal cues eg feeling upset, being drunk
Explanations for forgetting in LTM - retrieval failure - godden and baddeley (1975) context- dependent forgetting
Procedure - deep sea divers learned words and were later asked to recall them -
- condition 1 - Learn on land - recall on land
- condition 2 - learn on land - recall underwater
- condition 3 - learn underwater - recall on land
-condition 4 - learn underwater - recall underwater
Findings and conclusions - accurate recall was 40% lower in conditions 2 and 3 (mismatched contexts) than in conditions 1 and 4 (matched contexts). Retrieval failure was due to absence of encoded context cues at time of recall - material was not accessible (ie forgotten)
Explanations of forgetting in LTM - retrieval failure - carter and Cassaday (1998) state- dependent forgetting
Ptps learned lists of words/prose and later recalled them
- condition 1 - learn when on drug - recall on drug
- condition 2 - learn when on drug - recall not on drug
- condition 3 - learn when not on drug - recall on drug
- condition 4 - learn when not on drug - recall not on drug
Findings and conclusions- recall significantly worse on conditions 2 and 3 (mismatched cues) compared with conditions 1 and 4 (matched cues). When the cues at encoding are absent at retrieval (eg you are drowsy when recalling material but been alert when you learned it) then there is more forgetting.
Explanations of forgetting in LTM - retrieval failure - A03 - strength that retrieval cues have real-world application
People often go to another room to get an item but forgot what they wanted, but they remember again when they go back to the original room. When we have trouble remembering something, it is probably worth making effort to recall the environment in which you learned it first. This shows how research can remind us of strategies that we use in the real world to improve our recall
Explanations of forgetting in LTM - retrieval failure - limitation that context effects vary in recall and recognition
Godden and Baddeley (1980) replicated the underwater experiment using a recognition test instead of recall. There was no context- dependent effect. Findings with the same in all four conditions whether the contexts for learning and recall matched or not. This suggest that retrieval failure is a limited explanation for forgetting because it only applies when a person has to recall information rather than recognise it.
Explanations for forgetting in LTM - retrieval failure - criticism of encoding specificity principle
It isn’t easy to test. It leads to circular reasoning. In experience where a cue produces the successful recall of a word we assume the cue must’ve been encoded at the time of learning but they are just assumptions no way to independently establish whether the cue has really been encoded. It’s especially difficult to prove and disprove. If you can’t trust a theory scientifically, then we can’t trust that it is true and scientific. It’s not scientifically testable.
Factors affecting the accuracy of EWT - misleading information or leading questions
When you are asked a question the wording of it may lead or mislead you to give a certain answer. Issue for EWT because police questions may ‘direct’ a witness to give a particular answer. It goes through 3 stages
- (eyewitness memory) encoding - detailed events encoded into long-term memory and people involved my only be partial or distorted as crimes often happen quickly at night and can be accompanied by rapid, complex and violent action.
-retain - witness retains information for a period of time, memories may be lost or modified during retention and other activities between encoding and retrieval may interfere with the memory itself
- retrieval - witness retrieves information from storage during the reconstruction of the memory for example the presence or absence of appropriate retrieval cues or the nature of the questioning may significantly affect its accuracy.
Things can go wrong at each of these stages leading to unreliable memories.
Factors affecting the accuracy of EWT - misleading information and leading questions - loftus and palmer (1974)
So the effects of leading questions on memory of an event. They used 45 student participants to watch film clips of car accidents and then answer questions about speed. The critical question was ‘About how past where the cars going when they hit each other?’
There were five groups of ptps each given a different verb in the critical question : hit, contacted, bumped, collided or smashed.
Findings - the verb ‘contacted’ produced a mean estimated speed of 31.8mph. For the verb ‘smashed’, the mean was 40.5mph
The leading question (verb) biased eyewitnesses recall of an event. The verb ‘smashed’ suggested a faster speed of the car than ‘contacted’
Factors affecting accuracy of EWT - misleading information - why do leading questions affect EWT?
Response - bias explanation = wording of question has no enduring effect on an eyewitnesses memory of an event, but influences the kind of answer given. Eg word ‘smashed’ encouraged them to give a higher speed estimate
Substitution explanation = wording of a question does affect eyewitnesses memory, it interferes with the original memory, distorting its accuracy. Eg loftus and palmer (1974) conducted a second experiment that supported the substitution explanation - wording of the question changes the ptps memory of the film clip. Demonstrated as ptps who originally heard ‘smashed’ later were more likely to report seeing broken glass - there was none
Factors affecting accuracy of EWT - misleading information and leading questions - strength is realworld application in justice system
The consequences of inaccurate EWT are serious. Loftus (1975) argues police officers should be careful in phrasing questions to witnesses because of distorting effects. Psychologists are sometimes expert witnesses in trials and explain limits of EWT to juries. Therefore psychologists can improve how the legal system works and protect the innocent from faulty convictions based on unreliable EWT.
Counter - Loftus and Palmer showed film clips which was a different experience from a real life event as there’s less stress. Participants are also less concerned about the effects of their responses in a lab study - foster et al 1994. Therefore researchers may be too pessimistic about the effects of misleading information so EWT may be more reliable than studies suggest.
Factors affecting accuracy of EWT - misleading info and leading questions - A03 - limitation of substitution explanation is evidence challenging it
Sutherland and Hayne (2001) found out participants recall central details of an event better than peripheral ones even when asked misleading questions. This is presumably because the attention was focused on the central features and these memories were relatively resistant to misleading information. Therefore, the original memory of the event survived and was not distorted which is not predicted by the substitution explanation.
Counter - lab study - high internal validity but suffers from demand characteristics as ptps want to help so they guess when they can’t answer a question which lowers the internal validity. So to maximise internal validity researchers should reduce demand characteristics by removing cues that the ptps use to work out the hypothesis
Factors affecting accuracy of EWT - misleading information and leading questions - A03 - limitation evidence older people are less accurate than younger people
Andrasi and Rhodes (2006) people in age groups 18-25 and 35-45 are more accurate than 55-78 yrs. however all age groups more accurate when identifying people of their own age (called own age bias). Research studies often use younger people as the target to identify and may mean that some age groups appear less accurate but in fact this is not true
Factors affecting accuracy of EWT - what is post event discussion
When eyewitnesses to a crime discusses their experience and memories and their testimonies become contaminated because they combine information from each other’s memories so it can make their views inaccurate.
Factors affecting accuracy of EWT - why does post event discussion affect EWT
Source monitoring theory/ memory contamination = memories of events are genuinely distorted. The eyewitnesses can recall inaccurate and accurate information from the event but can’t recall where itcame from. they could’ve had it from someone else = source confusion. Happens when Cowitnesses discuss a crime and they mix information from other witnesses with their own memories.
Memory conformity - witnesses go along with each other to win social approval because they believe the other witnesses are right.
Factors affecting accuracy of EWT - post- event discussion - Gabbert et al (2003)
Participants watched the video of the same crime but films that each participant could see elements in the event that the other could not. Both participants discussed what they had seen on the video before individually completing a test of recall.
Findings- 71% of participants wrongly recalled aspects of the event they did not see the video but heard in the discussion.
In a control group, there was no discussion and no subsequent errors.
This was evidence of memory conformity.
Factors affecting accuracy of EWT - post event discussion - A03 - limitation of memory conformity but strength for memory contamination
Skagerberg and Wrights (2008) participants discussed film clips they had seen but there were two versions for example in one version of the mugger had dark brown hair and the other light brown. The participants discussed the clips in pairs each having seen different versions. The participants then recalled a ‘blend’ of what they had seen and what they have heard from their co-witnesses rather than one or the other for example said hair was medium brown. Suggests that the memory itself is distorted through contamination by post event discussion and is not the result of memory conformity
Factors affecting accuracy of EWT - post event discussion A03 - Gabbert et al - low ecological validity
The participants in the co-witness condition witnessed different perspective of the same crime as would typically be the case in real life crimes however like Loftus and Palmer the witnesses knew they were taking part in an experiment and more likely to have paid attention to the video clip, the results do not reflect every day examples of crime when witnesses may be exposed to less information.
Factors affecting EWT accuracy - post event discussion - A03- Gabbert et al - good population validity
They tested 2 different populations university students and older adults and little difference between the conditions so her results provide high population validity and allow us to conclude that post event discussion affects young and older adults in a similar way.
Factors affecting accuracy of EWT - post event discussion - A03 - Harmut and Bodier et al (2009)
Find the effects of post event discussion can be reduced if participants were warned of their impact. recall is more accurate for participants who are warned anything that they hear from co-witnesses is secondhand information and that they should forget it and recall only their own memory of the event.
Factors affecting accuracy of EWT - anxiety - negative impact
Anxiety creates physiological arousal in the body which prevents us from paying attention to important cues so recall is worse. For example the weapon focus effect is anxiety caused by seeing a weapon so all attention is on the weapon as it’s a source of danger to be avoided reducing witnesses recall of other details of the event. Stress in frightening situations may affect recall performance because of the stress involved.
Factors affecting EWT - anxiety - negative impact study to support - Johnson and Scott (1976)
Participants sat in a waiting room believing they were going to take part in a lab study.
- low- anxiety condition - participants had a casual conversation and then some man walking through the waiting room carrying a pen with grease on his hands.
- high- anxiety condition - a heated argument was accompanied by the sound of breaking Glass and a man then walked through the room holding a knife covered in blood. This creates anxiety and weapon ‘focus’.
Participants were later asked to pick the man from a set of 50 photographs .
Findings - 49% of participants in the low anxiety condition and 33% of high anxiety participants were able to identify the man. The tunnel theory of memory argues that people have enhanced memory for central events weapon focus as a result of an anxiety can have this affect
Factors affecting accuracy of EWT - anxiety - positive effect
The stress of witnessing a crime creates anxiety through physiological arousal in the body. This triggers the fight or flight response increasing alertness. this may improve memory for the event as we become more aware of cues in the situation.
Factors affecting accuracy of EWT - anxiety - positive effect - evidence to support - Yuille and Cutshall (1986)
Conducted a study of a shooting in a gun shop in Vancouver where a thief stole guns and money in broad daylight and the shop owner shot the thief dead. There were 21 witnesses and 13 agreed to participate in the study. Participants were interviewed 4 to 5 months after the incident and the information recalled was compared to the police interviews at the time of the shooting. Witnesses rated how stressed they felt at the time of the incident.
Findings and conclusions - witnesses were very accurate in what they recalled and there was little change after five months. Some details were less accurate such as age, weight and height. Participants who reported the highest levels of stress most accurate. This was about 88% compared to 75% for the less stressed group. Anxiety does not appear to reduce the accuracy of EWT for a real world event and may even enhance it.
Factors affecting accuracy of EWT - anxiety - explanation of the contradictory findings
Inverted - U theory = Yerkes and Dodson (1908) argue that the relationship between performance and arousal/stress is an inverted U. It says that performance/recall is best in moderately arousing conditions. Two little arousal and we don’t pay attention. however if stress levels get too high recall will fall as we struggle to concentrate.
Affects memory - Deffenbacher (1983) reviewed 21 studies of EWT, with contradictory findings on the effects of anxiety on recall. He suggests the Yerkes- Dodson effect could explain this - both low and high levels of anxiety produce poor recall whereas optimum levels can lead to very good recall.
Factors affecting accuracy of EWT - anxiety - A03 - limitation is that anxiety may not be relevant to weapon focus
Johnson and Scotts participants may have focused on the weapon not because they were anxious but because they were surprised. Pickel (1988) found accuracy in identifying the criminal was poorest when the object in their hand was unexpected for example raw chicken and a gun in a hairdressers which are both unusual. This suggests the weapons effect is due to unusualness rather than anxiety/threat and so tells us nothing about the specific effects of anxiety on recall.
Factors affecting accuracy of EWT - anxiety - A03 - supporting evidence for positive effects
Christianson and hübinette (1993) interviewed actual witnesses to bank robberies and some were direct victims (high anxiety) and others were bystanders (less anxiety). They found more than 75% accurate recall across all witnesses. Direct victims (most anxious) were even more accurate. This suggest that anxiety does not affect the accuracy of eyewitness recall and may even enhance it.
Counter - Christianson and hübinette interviewed witnesses long after the event. Many things happened that the researcher could not control for example post event discussion. Therefore, lack of control over confounding variables may be responsible for the inaccuracy of recall not anxiety.
Factors affecting accuracy of EWT - anxiety - A03 - supporting evidence for negative effects
Peters (1988) tested ptp who were attending their local health clinic for injections they met the researcher and nurse for equal periods of time and a week later were asked to identify them from photos. They recalled the researcher better than the nurse. Suggesting anxiety of having the injection had an impact on their memory of the nurse administering it.
Improving the accuracy of EWT - the cognitive interview what is is?
Based on psychological understanding of memory. Fisher and Geiselman (1992) claimed that EWT could be improved if the police used techniques based on psychological insights into how memory works. They called it the cognitive interview to indicate its foundation in cognitive psychology. Rapport or understanding is established with interviewee using four main techniques.
Improving the accuracy of EWT - the cognitive interview - technique 1 -report everything
Witnesses are encouraged to include every single detail of an event even if it seems irrelevant or the witness is not confident about it. Seemingly trivial details could be important and may trigger other memories.
Improving the accuracy of EWT - the cognitive interview - technique 2 - reinstate the context
The witness returns to the original crime scene ‘in their mind’ and imagines the environment eg the weather, what they could see. And their emotions eg what they felt. Based on the concept of context- dependent forgetting. Cues from the context may trigger recall.
Improving the accuracy of EWT - the cognitive interview - technique 3 - reverse the order
Events are recalled in a different order eg from the end back to the beginning or from the middle to the beginning.
Prevents people from basing their descriptions on their expectations of how the event must have happened rather than the actual events.
Also prevents dishonesty as harder to produce an untruthful account if it has to be reversed.
Improving the accuracy of EWT - the cognitive interview - technique 4 - changing perspective
Witnesses recall the incident from other people’s perspectives. How would it have appeared to another witness or to the perpetrator?
This prevents the influence of expectations and schema on recall. Schemas are packages of information developed through experience. They generate a framework for interpreting incoming information.
Improving the accuracy of EWT - the cognitive interview - the enhanced cognitive interview (ECI)
Fisher et al (1987) developed additional elements of the CI.
This includes a focus on the social dynamics of the interaction eg knowing when to establish and relinquish eye contact
The enhanced CI also includes ideas such as reducing the eyewitnesses anxiety, minimising distractions, getting the witness to speak slowly and asking open-ended questions.
Improving the accuracy of EWT - the cognitive interview - AO3 - limitation is that some elements of CI are more useful than others - Milne and Bull (2002)
Found that each individual technique of the cognitive interview alone produced more information than the standard police interview. But they also found that combining report everything and reinstate the context produced better recall than any other technique individually or combined. This casts doubt on the credibility of the overall cognitive interview because some of the techniques are less effective than the others.
Improving the accuracy of EWT - the cognitive interview - AO3 - limitation of the CI is that it is time consuming
Police are reluctant to use the cognitive interview because it takes more time than the standard police interview for example to establish rapport and allow the witness to relax. The cognitive interview also requires special training. The forces do not have the resources to provide more than a few hours of training. (Kebbell and Wagstaff 1997). This suggests that the complete cognitive interview is not realistic for police officers to use and it might be better to focus on just a few key elements.
Improving the accuracy of EWT - the cognitive interview - AO3 - Uk Kebbell et al 1999
Did a survey of police officers and found widespread use of CI. However although officers fond it useful and were concerned about amount of incorrect recall generated and time taken to interview. Seemed officers were using reinstate the context and report everything but rarely changing perspective and reverse order
Improving the accuracy of EWT - the cognitive interview - AO3 - support for the effectiveness of CI - Köhnken at al 1999
Did a meta- analysis and combined data from 55 studies comparing CI and ECI with the standard police interview. The CI produced an average 41% more correct information than the standard interview. Only four studies showed no difference. This shows that the CI is effective in helping witnesses recall information that is available but not accessible.
Counter - Köhnken at al also found increases in the amount of inaccurate information especially in the ECI - quantity over quality
Therefore police officers need to be very careful about how they treat eyewitness evidence from CIs/ECIs
Improving the accuracy of EWT - the cognitive interview - AO3 - limitation is there are lots of variations to the CI
Police forces take a ‘pick and mix’ approach in practice which makes it hard to compare effectiveness in studies. However this approach makes the CI more flexible because police forces or individuals evolve their own approaches depending on what they think works best. This variation is a benefit of the CI because it can be adapted to different situations increasing its credibility for officers though not for empirical research.
Improving the accuracy of EWT - the cognitive interview - AO3 - real life application
Fisher et al 1990 - in real police settings in Miami where police were trained in ECI techniques and used on genuine crime witnesses. There was a significantly enhanced amount of info recalled.
Stein and Memon 2006 - compared normal interviewing techniques and CI in Brazil. CI increased the amount of correct info. This shows the interview worked in another culture suggesting that the research has validity cross-culture.
Who proposed theory on types of LTM
Tulving 1972 who proposed a distinction between episodic, semantic and procedural memory
Limitation of types of LTM - cohen and squire - there are only two types
Cohen and squire disagree with the classification of LTM into three types instead proposing that there are just two types of LTM, simplifying Tulving divisions into declarative and non - declarative memory claiming that whether the memory was conscious or unconscious is the most significant factor in differentiating between memory types. Nonetheless Tulving theory of three types of memory is a great improvement of the simplistic, unitary store for LTM that appears in the MSM and has been extremely influential in the field of LTM, recognising that LTM is a complex process and that LTM has a biological basis in a variety of Brain areas.
Strength of types of LTM - applications
- understanding these types of memory can help with rehabilitation with memory problems and specific treatments can be developed eg problems with procedural or semantic knowledge.
Evidence of post event discussion - loftus and pickrell
Loftus and Pickrell (2003) suggested to participants
that they had met Bugs Bunny at Disneyland many
years earlier (which could not have occurred) and ptp then later recalled seeing bugs bunny this supports idea that post event discussion affected their memories they become contaminated because they combine information from their own memory with other witnesses.
