Memory Flashcards
Coding
The format in which information is stored in the various memory stores
Capacity
The amount of information that can be held in a memory store
Duration
The length of time information can be held in memory
Short-term memory
The limited capacity memory store. Coding is mainly acoustic (sounds), capacity is 7+-2 items on average, duration is between about 18 and 30 seconds
Long-term memory
The permanent memory store. Coding is mainly semantic (meaning), it has unlimited capacity and can store memories for up to a lifetime
Research on coding
Alan baddeley
He gave different lists of words for groups of participants to remember:
group 1- acoustically similar
Group 2 – acoustically dissimilar
Group 3 -semantically similar
Group 4-semantically dissimilar
Participants were shown the original words and asked to recall them in the correct order. When they had to this recall task immediately after hearing it (STN Rico), they tended to do worse with acoustically similar words
If participants were asked to recall the words list after a time interval of 20 minutes (LTM recall), they did worse with the semantically similar words. This suggests that information is coded semantically in LTM
Acoustically similar
Words sounding similar
Cat cab can
Acoustically dissimilar
Words sounding different
Pit few cow
Semantically similar
Words with similar meaning
Great large big
Semantically dissimilar
Words that all had different meanings
Good huge hot
Research on capacity - digit span
How much information can STM hold at any one time, i.e. what is the capacity? Joseph Jacobs developed a technique to measure digit span. Researcher gives for example, four digits and then the participant is asked to recall it in the correct order out loud. If this is correct the researcher reads out 5 digits and so on until the participant cannot record the order correctly. This determines the individuals’ digit span
He found that the mean span for digits across all participants was 9.3 items. The main span for letters was 7.3
Research on capacity – span of memory and Chunking
George Miller made observations of everyday practice. For example, he noted that things come in sevens: there are seven notes on the musical scale, seven days of the week, seven deadly sins, and so on. This suggests that the span (or capacity of STM) is about seven items. However, Miller also noted that people can recall 5 words as well as they can recall five letters. They do this by chunking – bunching sets of digits or letters into units or chunks
Research on duration - STM
Margaret and Lloyd Peterson tested 24 undergraduate students
Each student took part in 8 trials. On each trial the student was given a consonant syllable (also called a trigram, such as YCG) to remember and was also given a 3 digit number
Student was then asked to found backwards from that 3 digit number until they were told to stop
The counting backwards was to prevent any mental rehearsal
On each trail they were told to stop after a different amount of time -3,6,9,12,15 or 18 seconds. This is called retention interval
Findings suggest that STM may have a very short duration, unless we repeat something over and over again
As retention interval (seconds) increased, % of correct responses decreased
Research on duration - LTM
Harry Bahrick studies 392 participants in Ohio aged 17 to 74
High school yearbooks were obtained. Recall was tested in various ways, including: 1. Photo recognition test consisting of 50 photos, some from the year book, 2. Free recall test where ps recalled all the names of their graduating class
Ps who were tested within 15 years of graduation were about 90% accurate in photo recognition. After 48 years, recall declined to about 70% for photo recognition
Free recall was less good than recognition. After 15 years this was about 60% accurate
This shows that LTM can last a long time
Baddeley research on coding evaluation
Artificial stimuli
One limitation of his study was that it used quite artificial stimuli rather than meaningful material
The word lists had no personal meaning to participants. This means we should be cautious about generalising the findings to different kinds of memory task. E.g. when processing more meaningful info, people may use semantic coding even for STM tasks.
This suggests that the findings from this study have limited application
Jacobs research on capacity - digit span evaluation
Lacking validity
One limitation of the study is that it was conducted a long time ago. Early research in psychology often lacked adequate control
E.g. some participants may have been distracted while they were being tested so they didn’t perform as well as they might
This would mean that the results might not be valid because there were confounding variables that weren’t controlled
However the results of this study have been confirmed in other research, supporting its validity
Millers research on capacity - span of memory and chunking evaluation
Not so many chunks
One limitation of his research is that he might have overestimated the capacity of STM
E.g. Cowan reviewed other research and concluded that the capacity of STM was only about 4 chunks
This suggests that the lower end of millers estimate (5 items) is more appropriate that 7 items
Peterson’s research on duration of STM evaluation
A limitation of the study is that the stimulus material was artificial. Trying to memorise consonant syllables does not reflect most real life memory activities where what we are trying to remember is meaningful. So we might say that this study lacked external validity
However, we do sometimes try to remember fairly meaningless things, such as phone numbers, so the study is not totally irrelevant
One explanation for why we forget things in STM is that the memory trace simply disappears if not rehearsed (spontaneous decay). An alternate explanation is that the info in STM is displaced- the STM has a limited capacity and any new info will push out what is currently there. In the Peterson study ps counted down during the retention interval
Bahricks Study on duration of LTM evaluation
Higher external validity
One strength of the study is that it has higher external validity. Real life meaningful memories were studied. When studies on LTM have been conducted with meaningless pictures to be remembered, recall rates were lower (e.g. Shepard)
The downside of such real life research is that confounding variables are not controlled, such as the fact that his participants may have looked at the yearbook photos in the past and rehearsed their memory over the years
Multi store model
A representation of how memory works in terms of three stores called sensory register, short-term memory and long term memory. It also describes how information is transferred from one store to another, how it is remembered and how it is stored
Sensory register
The memory stores for each of our five senses, such as vision (iconic store) and hearing (echoic store ). Coding in the iconic sensory register is visual and in the echoic sensory register it is acoustic. The capacity of sensory registers is huge (millions of receptors) and information last for a very short time (less than half a second)
The case of HM
HM underwent brain surgery to relieve his epilepsy. Unfortunately for him, the procedure used was in its infancy and not fully understood. Crucially, a part of his brain known as the hippocampus was removed from both sides of his brain. We now know this is to be the central to memory function. When his memory was assessed in 1955, he thought the year was 1953, and that he was 27 (was 31) years old. He had very little recall of the operation and he could not remember speaking to someone just an hour earlier
His LTM was tested over and over again but never improve with practice. He would read the same magazine repeatedly without remembering it. He couldn’t recall what he has eaten earlier the same day. However, despite all this, he performed well on tests of immediate memory span, a measure of STM
Evaluation of the MSM
Supporting research evidence There is more than one type of STM There is more than one type of rehearsal Artificial materials There is more than one type of LTM
Supporting research evidence of the MSM evaluation
A major strength of the MSM is that it is supported by research studies that show that STM and LTM or indeed qualitatively different. E.g. Baddeley found that we tend to mix up words that sound similar when we are using our STMs. But we mix up words that have similar meanings when we use our LTMs. The strength of the study is that it clearly shows the coding in STM is acoustic and in LTM it is semantic. So they are different and this supports the MSMs view that these two memory stores are separate and independent
Further support is given by all the studies of coding, capacity and duration
There is more than one type of STM evaluation of MSM
The MSM states that STM is a unitary store, in other words there is only one type of short-term memory. However, evidence from people suffering from a clinical condition called amnesia shows that this cannot be true. E.g. Shallice and Warrington studied a patient with amnesia known as KF. They found that his STM for digits was very poor when they read them out loud to him. But his recall was much better when he was able to read the digits to himself. Further studies of KF and other people with amnesia showed that there could even be another Short-term store for non-verbal sounds (such as noises)
The unitary STM is a limitation of the MSM because research shows that at the very least there must be one short-term store to process visual information and another one to process auditory information. The working memory model includes the separate stores
There is more than one type of rehearsal evaluation of MSM
According to the MSM, what matters in rehearsal is the amount of it that you do
So the more you rehearse some information, the more likely you are to transfer it to LTM and remember it for a long time
However Craik and Watkins found that this prediction is wrong
What really matters about rehearsal is the type. They discovered that there are two types of rehearsal. Maintenance rehearsal is the type described in the MSM, but this does not transfer information into LTM. It just maintains it in STM, hence the name
Elaborative rehearsal is needed for long-term storage. This occurs when you link the information to your existing knowledge, or you think about what it means
This is a very serious limitation of the MSM because it is another research finding that cannot be explained by the model
Artificial materials evaluation of MSM
In every day life we form memories related to all sorts of useful things – people’s faces, their names, facts and so on
But a lot of the research studies that provide support for the MSM use none of these materials. Instead they use digits, letters and sometimes words. They even use what are known as consonant syllables that have no meaning
There is more than one type of LTM evaluation of MSM
There’s a lot of research evidence the LTM, like STM, is not a unitary memory store
For example, we have one long-term store for our memories of facts about the world, and we have a different one for our memories of how to ride a bicycle.
Types of LTM
Episodic memory
Semantic memory
Procedural memory
Episodic memory
A LTM store for personal events
It includes memories of when the events occurred and of the people, objects, places and behaviours involved
Memories from this store have to be retrieved consciously and with effort
Episodic memories example
The breakfast you ate this morning
Semantic memory
A LTM store for our knowledge of the world
Includes facts and our knowledge of what words and concepts mean
These memories usually also need to be recalled deliberately
Semantic memories example
The taste of an orange
Procedural memory
LTM store for our knowledge of how to do things
Includes our memories of learned skills
We usually recall these memories without making a conscious or deliberate effort
Procedural memory example
Driving a car
Types of LTM evaluation points
Clinical evidence Neuroimaging evidence Real life applications Problems with clinical evidence 3 or 2 types of LTM
Clinical evidence evaluation of types of LTM
Case studies of HM and Clive Wearing
Episodic memory in both men was severely impaired as a consequence of amnesia. They had great difficulty recalling events that had happened to them in their pasts
But their semantic memories were relatively unaffected
E.g. they still understood the meaning of words
This evidence supports Tulving’s view that there are different memory stored in LTM
Neuroimaging evidence evaluation of types of LTM
There is evidence from brain scan studies that different types of memory is stored in different parts of the brain.
E.g. Tulving got their participants to perform various memory tasks while their brain was scanned using a PET scanner. They found the episodic and semantic memories were both recalled from an area of the brain that was the prefrontal cortex. This area is divided Into, one on each side of the brain. The left prefrontal cortex was involved in recalling semantic memories. Episodic memories were recalled from the right prefrontal cortex
The strength of this finding is that it supports the view that there is a physical reality to the different types of LTM within the brain. It has also been confirmed many times we need to research studies, further supporting the validity of this
Real life applications evaluation of types of LTM
Being able to identify different aspects of LTM allows psychologists to target certain kinds of memory in order to better peoples lives.
E.g. Belleville demonstrate that episodic memories could be improved in older people who had a mild cognitive impairment. The trained participants performed better on a test of episodic memory after training then a control group
Your episodic memory is a type of memory most often affected by mild cognitive impairment, which highlights the benefit of being able to distinguish between types of LTM – because it enables specific treatments to be developed
Problems with clinical evidence evaluation of types of LTM
Psychologists are very interested in studying people with brain injuries. People like Clive wearing and HM have provided a lot of useful information about what happens when memory is damaged. This has even helped research to understand how memory is supposed to work normally. But such clinical studies are not perfect. For instance there is a serious lack of control of all sorts of different variables in clinical studies
Three types of LTM or two? Evaluation of LTM
Cohen and Squire disagree with Tulving’s division of LTM into three types. They accept that procedural memories represent one type of LTM. But they argue that episodic and semantic memories are stored together in one LTM store that they called declarative memory i.e. memories can be consciously recalled. In contrast procedural memories are non-decorative
Working memory model
A representation of STM. It suggests that STM is a dynamic processor of different types of information using subunits coordinated by a central decision-making system
Central executive
The component of the WNM that coordinates the activities of the three subsystems in memory. It also allocates processing resources to those activities
Phonological loop
The component of the WMM that processes information in terms of sound. This includes both written and spoken material. It’s divided into the phonological store and the articulatory process
Visuo – spatial sketch pad
The component of the WMM that processes visual and spatial information in a mental space often called our inner eye
Episodic buffer
The component of the WMM that brings together material from the other subsystems into a single memory rather than separate strands. It also provides a bridge between working memory and long term memory
The phonological store
Stores the words you hear
The articulatory process
Allows maintenance rehearsal (repeating sounds or words in a loop to keep them in working memory while they are needed). The capacity of this loop is believed to be two seconds worth of what you can say
What is the visuospatial sketch pad divided into
The visual cache and the inner scribe
Visual cache
Stores Visual data
Inner scribe
Records the arrangement of objects in the visual field
Evaluation points of the working memory model
Clinical evidence
Dual task performance
Lack of clarity over the central executive
Brain scanning studies support the WMM
Clinical evidence evaluation of the WMM
Support for it comes from Shallice and Warrington’s case study of patient KF who had suffered brain damage
After this damage happens KF had poor STM ability for verbal information but could process visual information normally presented ie he had difficulty with sounds but could recall letters and digits. This suggested that just his phonological loop has been damaged leaving other areas of memory intact
This supports the existence of a separate visual and acoustic store. However, evidence from brain damage patients may not be reliable because it concerns unique cases with patients who had had traumatic experiences
Dual task performance evaluation of the WMM
Studies of dual task performance support the existence of the visuospatial sketch pad
Baddeley showed that participants had more difficulty doing two visual tasks than doing a visual and verbal task at the same time. This increased difficulty is because both visual tasks compete for the same slave system whereas, when doing a verbal and visual task simultaneously, there is no competition
This means there must be a separate slave system that processes visual input
Lack of clarity over the central executive evaluation of WMM
Cognitive psychologists suggest that this component of the WMM is unsatisfactory as doesn’t really explain anything. Baddeley himself recognised this when he said, the central executive is the most important but the least understood component of the working memory. The central executive needs to be more clearly specified than just being simply attention. For example some psychologists believe that it may consist of separate components. This means that the WMN hasn’t been fully explained
Brain scanning studies support the WMM evaluation of the WMM
Braver gave the participants tasks that involved the central executive while they were having a brain scan. The research has found great activity in an area known as the prefrontal cortex. What was especially interesting was that the activity in this area increased as the tasks became harder. This makes a lot of sense in terms of the WMM: as demands of the CE increase, it has to work harder to fulfil its function
Interference
Forgetting because one memory blocks another, causing one or both memories to be distorted
Proactive interference
Forgetting occurs when older memories, already stored, disrupts the recall of new memories. The degree of forgetting is greater when the memories are similar
Retro active interference
Forgetting occurs when newer memories disrupt the recall of older memories already stored
The degree of forgetting is greater when the memories are similar
Interference theory
Some Forgetting takes place because of interference
This happens when two pieces of information conflict with each other, resulting in forgetting
Effects of similarity on interference theory
In both cases, the interference is worse when the memories are similar as discovered by John McGeoch and William McDonald
Effects of similarity McGeoch and McDonald procedure
Studied retroactive interference by changing the amount of similarity between two sets of materials
Ps had to learn a list of words until they could remember them with 100% accuracy
They then learned a new list. There were 6 groups of ps who had to learn different types of lists:
-Synonyms (words with same meanings as the originals)
-Antonyms (opposite meanings to originals)
-Words unrelated to originals
-Nonsense syllables
-Three digit numbers
-No new list
Effects of similarity McGeoch and McDonald findings
When the ps then recalled the original list of words, their performance depended on the nature of the second list. The most similar material (synonyms) produced the worst recall
This shows that interference is strongest when the memories are similar
Interference theory evaluation points
Evidence from lab studies
Artificial materials
Real life studies
Time between learning
Evidence from lab studies- evaluation of interference theory
Thousands of lab experiments have been carried out into this explanation for forgetting
Eg McGeoch and McDonald’s research. Most of these studies show that both types of interference are very likely to be common ways we forget info from LTM
This is a strength because lab experiments control the effects of irrelevant influences
Artificial materials- evaluation of interference theory
There is a much greater chance that interference will be demonstrated in the lab than in real life situations
The stimulus materials used in most studies are lists of words. The task facing ps is to learn lists of consonant syllables. Which isn’t like stuff we learn and try to remember everyday eg people’s faces, their bdays.
This is a limitation because the use of artificial tasks makes interference much more likely in the lab. It may not be as likely an explanation for forgetting in everyday life
Real life studies- evaluation of interference theory
Some studies have considered interference effects in more everyday situations
Baddeley and Hitch wanted to find out if interference was a better explanation for forgetting than the passage of time. They asked rugby players to remember the names of the teams they had played so far in that season, week by week. Because most of the players had missed games, for some the last team they played might’ve been two weeks ago or 3 or more. The results showed that accurate recall didn’t depend on how long ago the matches were. What was more important was the number of games they played in the meantime. So a player’s recall of a team from 3 weeks ago was better if they had played no matches since then.
This study shows that interference explanations can apply to at least some everyday situations.
Retrieval failure
A form of forgetting. It occurs when we don’t have the necessary cues to access memory. The memory is Available but not accessible unless a suitable cue is provided
Cue
A trigger of information that allows us to access a memory
Such cues may be meaningful or may be indirectly linked by being encoded at the time of learning
For example, cues may be external (environmental context) or internal (mood or degree of drunkness)
Retrieval failure theory- encoding specificity principle
Tulving- reviewed research into retrieval failure and discovered a consistent pattern to the findings
He summarised this pattern in what he called the encoding specificity principle. This states that if a cue it to help us to recall information it has to be present at encoding (when we learn the material) and retrieval (when we are recalling it). It follows from this that if the cues available at encoding and retrieval are different there will be some forgetting
Some cues are linked to the material-to-be-remembered in a meaningful way.
Retrieval failure theory- context dependent forgetting
Godden and Baddeley carried out a study of deep sea divers working underwater
Procedure- divers learnt a list of words either underwater or on land and then were asked to recall the words either underwater or on land
4 conditions- learn on land recall on land, learn on land recall under water and vice versa
Findings- in two of these conditions the environmental contexts of learning and recall matches, whereas in the other two they didn’t. Accurate recall was 40% lower in the non matching conditions. The external cues available at learning were different from the ones at recall and this led to retrieval failure
Retrieval failure theory- state dependent forgetting
Procedure- Carter and Cassaday gave antihistamines to their participants. The antihistamines has a mild sedative effect making the ps slightly drowsy. This creates an internal physiological state different from the normal state of being awake and alert. The ps had to learn lists of words and passages of prose and then recall the info
Conditions- learn on drug recall when on it, learn on it recall off it and vice versa
Findings- in the conditions where there was a mismatch between internal state at learning and recall, performance on the memory test was significantly worse. So when the cues are absent then there is more forgetting
Retrieval failure theory evaluation points
Supporting evidence
Questioning context effects
Recall versus recognition
Supporting evidence evaluation of retrieval failure theory
A range of research supports the retrieval failure explanation for forgetting. The studies by Godden and Baddeley and Carter and Cassaday are examples.
This is a strength because supporting evidence increases the validity of an explanation. This is especially true when the evidence shows that retrieval failure occurs in real life situations as well as in the highly controlled conditions of the lab
Questioning context effects evaluation of retrieval failure theory
Baddeley argues that context effects are actually not very strong, especially in real life. Different contexts have to be very different indeed before an effect is seen.
Eg it would be hard to find an environment as different from land as underwater. In contrast, learning something in one room and recalling it in another is unlikely to result in much forgetting because these environments are generally not different enough
This is a limitation because it means that the real life applications of retrieval failure due to contractual cues don’t actually explain much forgetting
Recall versus recognition evaluation of retrieval failure theory
The context effect may be related to the kind of memory being tested.
Godden and Baddeley replicated their underwater experiment but used a recognition test instead of recall- ps had to say whether they recognised a word read to them from the list, instead of retrieving it for themselves. When recognition was tested there was no context dependent effect; performance was the same in all four conditions
This is a limitation of context effects because it means that the presence of absence of cues only affects memory when you test it in a certain way
Eyewitness testimony
The ability of people to remember the details of events, such as accidents and crimes, which they themselves have observed. Accuracy of EWT can be affected by factors such as misleading information, leading questions and anxiety
Misleading information
Incorrect information given to the eyewitness usually after the event
It can take many forms, such as leading questions and post event discussion between two co witnesses and/or other people
Leading question
A question which, because of the way it is phrased, suggests a certain answer
Post event discussion
Occurs when there is more than one witness to an event
Witnesses may discuss what they have seen with co witnesses or with other people. This may influence the accuracy of each witness’ recall of the event
Leading questions procedure
Loftus and Palmer
They arranged for participants to watch film clips of car accident and then gave them questions about the accident. In the critical question (a leading q) ps were asked to describe how fast the cars were travelling
“About how fast were the cars going when they hit each other?”
This is a leading q because the verb “hit” suggests the speed the car was going. There were 5 groups of ps, each was given a different verb in the critical q. Hit, contacted, bumped, collided and smashed
Leading questions findings
Loftus and Palmer
The mean estimated speed was calculated for each p group. The verb contacted resulted in a mean estimated speed of 31.8 mph. For the smashed the mean was 40.5 mph
The leading q biased the EW recall of the event
Post event discussion procedure
Gabbert
She studied ps in pairs. Each p watched a video of the same crime, but filmed from different points of view. This meant that each p could see elements in the event that the other couldn’t
Eg only one of the ps could see the title of a book carrier by a woman
Both ps then discussed what they had seen before individually completing a test of recall
Post even discussion findings
Gabbert
The researchers found that 71% of the ps mistakenly recalled aspects of the event that they didn’t see in the video but had picked up in the discussion
The corresponding figure in a control group, where there was no discussion, was 0%
Gabbert concluded that witnesses often go along with each other, either to win social approval or because they believe the other witnesses are right and they are wrong
Factors affecting eyewitness testimony: misleading information evaluation points
Useful real life applications
The tasks are artificial
Individual differences
Useful real life applications evaluation of misleading information
A great strength of all research into misleading information is that it has hugely important practical uses in the real world, where the consequences of inaccurate EWT can be very serious indeed.
E.g. Loftus believes that leading questions can have such a distorting effect on the memory that police officers need to be careful about how they phrase the questions when interviewing eyewitnesses
Research into EWT is one area in which psychologists believe they can make an important positive difference to the lives of real people, for instance by improving the way the legal system works and by appearing in court trials as expert witnesses
The tasks are artificial evaluation of misleading information
A real limitation of Loftus and Palmer’s study is that the participants watched film clips of car accidents. This is a very different experience from witnessing a real accident, mainly because such clips lack the stress of a real accident. There is some evidence that emotions can have an influence on memory.
This is a limitation because studies that use such artificial tasks may tell us very little about how leading questions affect EWT in cases of real accidents or crimes. It could even be that researchers such as Loftus are too pessimistic about the accuracy of EWT – it may be more reliable than many studies suggest
Individual differences evaluation of misleading information
There is evidence that older people are less accurate than younger people when giving eyewitness reports. For example Anastasia and Rhodes found that people in age groups 18 to 25 and 35 to 45 are more accurate than people in the group 55 to 78 years. However all age groups are more accurate when identifying people of their own age group (called an age bias)
Research studies often use younger people as the target to identify and this may mean that some age groups appear less accurate but in fact this is not true
Anxiety
A state of emotional and physical arousal. The emotions include having worried thoughts and feelings of tension. Physical changes include an increased heart rate and sweatiness. Anxiety is a normal reaction to stressful situations, but can affect the accuracy and detail of eyewitness testimony
The affects of anxiety
Anxiety has a negative effect on recall
Anxiety has a positive effect on recall
Anxiety has a negative effect on recall procedure
Johnson and Scott
They lead participants to believe that they were going to take part in a lab study. Whilst seated in a waiting room participants heard an argument in the next room. In the low anxiety condition a man then walked through the waiting area, carrying a pen and with the grease on his hands. Other participants overheard the same heated argument, but this time accompanied by the sound of breaking glass. A man walked out of the room, holding a paper knife that was covered in blood. This was the high anxiety condition
Anxiety has a negative effect on recall findings
Johnson and Scott
The participants later picked out the man from a set of 50 photos; 49% of the participants who had seen the man carrying the pen were able to identify him. The corresponding figure for the participants who had seen the man holding the blood covered knife was just 33%. The tunnel theory of memory argues that a witness’ attention narrows to focus on the weapon, because it’s a source of anxiety
Anxiety has a positive effect on recall procedure
Yuille and Cutshall
They conducted a study of a real life shooting in a gun shop in Vancouver, Canada. The shop owner shot a thief dead. There were 21 witnesses – 13 agreed to take part in the study. The interviews were held 4 to 5 months after the incident and these were compared with the original police interviews made at the time of the shooting. Accuracy was determined by the number of details reported in each account. The witnesses were also asked to rate how stressed they had felt at the time of the incident, using a seven point scale, and asked if they had any emotional problems since the event, such as sleeplessness
Anxiety has a positive effect on recall findings
Yuille and Cutshall
The witnesses were very accurate in their accounts and there was little change in the amount of accuracy after five months – there is some details were less accurate, such as recollection of the colour of items and age/height/weight estimates. Those participants who reported the highest levels of stress were most accurate (about 88% compare to 75% for the less stress group)
Explain the contradictory findings between anxiety having a positive effect and negative effect on recall
According to Yerkes and Dodson the relationship between emotional arousal and performance looks like an inverted U
Deffenbacher applied the Yerkes-Dodson Law to EWT. Lower levels of anxiety produce lower levels of recall accuracy. But memory becomes more accurate as the level of anxiety experienced increases, just as you’d expect from the graph. However, there comes a point where the optimum level of anxiety is reached. This is the point of maximum accuracy. If an eyewitness experiences any more stress on this, then the record of the event suffers a drastic decline
Factors affecting eyewitness testimony: anxiety evaluation points
Weapon focus effect may not be relevant
Field studies sometimes lack control
There are ethical issues
Weapon focus effect may not be relevant evaluation of anxiety
The study by Johnson and Scott on the weapon focus may test surprise rather than anxiety. The reason participants focus on the weapon may be because they’re surprised at what they see rather than because they’re scared.
Pickel conducted an experiment using scissors, a handgun, a wallet or a raw chicken as the handheld items in a hairdressing salon video (where scissors would be low anxiety, low unusualness). Eyewitness accuracy was significantly poorer in the high unusualness conditions (chicken and handgun)
This suggests that the weapon focus effect is due to unusualness rather than anxiety/threat and therefore tells us nothing specifically about the effects of anxiety on EWT
There are ethical issues evaluation of anxiety
Creating anxiety in participants is very risky. It is potentially unethical because it may subject people to psychological harm purely for the purposes of research. This is why real life studies are so beneficial – psychologists interview people who have already witnessed a real life event, so there is no need to create it.
This issue doesn’t challenge the findings from studies such as Johnson and Scott but it does question the need for such research. One reason is to compare findings with the less controlled field studies – and the benefits of this research may outweigh the issues
Field studies sometimes lack control evaluation of anxiety
Researchers usually interview real life eyewitnesses sometime after the event. All sorts of things will happen to the participants in the meantime that the researchers will have no control over – discussions with other people about the event, accounts they may have read or seen in the media, the effects of being interviewed by the police, and so on (i.e. post event discussion). This is a limitation of field research because it is possible that these extraneous variables may be responsible for the accuracy of recall
The effects of anxiety may be overwhelmed by these other factors, and impossible to assess by the time the ps are interviewed
Cognitive interview
A method of interviewing EWs to help them retrieve more accurate memories. It uses four main techniques, all based on well established psychological knowledge of human memory- report everything, reinstate the context, reverse the order and change perspective
Report everything – the cognitive interview
Witnesses are encouraged to include every single detail of the event, even though it may seem irrelevant or the witness doesn’t feel confident about it. Seemingly trivial details may be important and, moreover, they may trigger other important memories
Reinstate the context – the cognitive interview
The witness should return to the original crime scene in their mind and imagine the environment (such as what the weather was like, what they could see) and their emotions (such the way they were feeling)
Reverse the order – the cognitive interview
Event should be recalled in a different chronological order to the original sequence, for example, from the final point back to the beginning, or from the middle to the beginning.
This is done to prevent people reporting their expectations of how the events must’ve happened rather than the actual events. It also prevents dishonesty (it’s harder for people to produce an untruthful account if they have to reverse it)
Change perspective – the cognitive interview
Witnesses should recall the incident from other peoples perspectives. For example, how it would have appeared to other witnesses or to the perpetrator. This is done to disrupt the effects of expectations and schema on record. The schema that you have for a particular setting (such as going into a shop) generate expectations of what would have happened this is the schema that is recalled rather than what actually happened
The enhanced cognitive interview
Fisher developed some additional elements to the CI to focus on the social dynamics of the interaction. E.g. the interviewer needs to know when to establish eye contact and went to relinquish it. The ECI also includes ideas such as reducing eyewitness anxiety, minimising distractions, getting a witness to speak slowly and asking open ended questions
Improving the accuracy of eyewitness testimony: cognitive interview evaluation points
The CI is time-consuming
Some elements may be more valuable than others
Support for the effectiveness of ECI
The CI is time-consuming evaluation of the cognitive interview
Police may be reluctant to use the CI because it takes much more time than the standard police interview.
E.g. more time is needed to establish rapport with the witness and allow them to relax. The CI also requires special training and many forces have not been able to provide more than a few hours
This means it is unlikely that the proper version of the CI is actually used, which may explain why police have not been that impressed by it
Some elements may be more valuable than others evaluation of the cognitive interview
Milne and Bull found that each individual element was equally valuable. Each technique use singly produce more information than the standard police interview. However Milne and Bull found that using a combination of report everything and context reinstatement produced better recall than any of the other conditions. This confirmed police officers’ suspicions that some aspects of the CI are more useful than others
This finding is a strength because it suggests that at least these two elements should be used to improve police interview of eyewitnesses even if the full CI isn’t used. This in turn increases the credibility of the CI amongst those who use it – police officers
Support for the effectiveness of the ECI evaluation of the cognitive interview
Research suggests that enhanced cognitive interview may offer special benefits.
E.g. a meta analysis by Kohnken combined data from 50 studies. The enhanced CI consistently provided more correct information than the standard interview used by police.
This is a strength because studies such as this one indicate that there are real practical benefits to the police using the enhanced version of the CI. The research shows that it gives the police a greater chance of catching and charging criminals, which is beneficial to the society as a whole
