Memory
Coding capacity and duration of memory
The multi-store model
Types of LTM
The working memory model - explanation of STM and how it functions. Consists of 4 main components:
Explanations for forgetting - Interference
Explanations for forgetting - Retrieval failure
Factors affecting the accuracy of EWT: Misleading info
Factors affecting the accuracy of EWT: Anxiety
Improving the accuracy of EWT: Cognitive interview
Research on codiing - The process of converting info from one group to another. Alan Baddeley (1966a and 1966b) gave different lists of words for 4 groups of ppts to remember
Group 1 = acoustically similar
Group 2 = acoustically dissimilar
Group 3 = semantically similar
Group 4 = semantically dissimilar
When ppts were asked to immediately recall the lists of words, they did worse on the acoustically similar list
If ppts were asked to recall the words after a 20 min interval, they did worse on semantically similar words. This suggests that info is coded semantically in LTM
Evaluation - Artificial stimuli - Used artificial stimuli rather than meaningful material. The word lists had not personal meaning to the ppts/ This means we should be cautious about generalising the findings to different kinds of memory tasks. For example, when coding more meaningful info, an individuals may use semantic coding even for STM tasks --> limited application
Research on capacity - Digit span - Jacobs (1887) gave ppts 4 digits and then asked ppts to recall these in the correct order. The researcher then gives the ppt 5 digits, 6 digits and so one until they are unable to recall the digits correctly. Jacobs found the mean span for digits was 9.3 items and for letter 7.3 items
Span of memory and chunking - George Miller (1956) noted that things cool win sevens. This suggest that the span or capacity for STM is about 7 items (plus or minus 2). Chunking is a method that can be used too improve the amount of info you can recall. This involves grouping sets of letters or digits into groups or chunks
Evaluation - Lacks validity - Jacob's study was conducted a long time ago. Early research often lacked adequate control. eg. some ppts may have been distracted whilst they were being tested so lacked focus. Therefore, results may not be valid because there was cofounding variable that were not controlled. However, the results of this research has been confirmed in other studies, supporting its validity
Not so many chunks - Miller's research may have overestimated the capacity of STM. Cowan (2001) reviewed other research and concluded that the coding go STM was only about 4 chunks. Therefore the lower end of Miler's predictions was more appropriate.
Research on duration -
Duration of STM - Peterson and Peterson (1959) tested 24 undergraduate students. Each student took part in 8 trials. On each trial the student was given a consonant syllable (eg. YHG) as well as a 3 digit number to remember. The student was then asked to count back from that 3 digit number until told to stop (this was to prevent mental rehearsal). On each trail, they were told to stop after a different amount of time - 3,6,9,12,15,18 seconds.
Findings - STM has a very short duration (18 seconds) unless verbal rehearsal takes place
Duration of LTM - Bahrick and his colleagues (1975) studied 392 ppts from Ohio aged between 17 and 74. High school year books were obtained from the students. Recall was tested by:
1) photo-recognition test of 50 photos (only some from yearbook)
2) Free recall - ppts recalled names of their graduating class
Findings -
Ppts who were tested within 15 years of graduation were about 90% accurate in photo recognition. After 48 years, recall decline to about 48% for photo recog
Free recall = 60% after 15 years
30% after 48 years
Meaningless stimuli in STM study - The stimulus material was artificial. Trying to memories consonant syllables does not reflect most real-life memory activities where what we are trying to remember is meaningful. Therefor, the study lacks external validity
Higher external validity - One strength of Bahrick's study is that it studies real-life meaningful memories. When studies on LTM have been conducted with meaningless pictures, recall rates were lower. However, confounding variables have not been controlled. For example, ppts may have looked atthie yearbook and rehearsed their memory over the years
Peterson and Peterson study does not account for displacement only for retention intervals
Atkinson and Shiffrin (1968,1971) - MSM describes how information flows through the memory system. Memory is made up of 3 stores:
Sensory register - Stimuli from the environment passes into the sensory register. Contains one store for each f our five senses. 2 main stores = iconic (visual info) and echoic memory (sound - coded acoustically). Duration is less than half a second with a very high capacity. Infro moves from sensory register to STM, if it is paid attention to
STM - Can only contain a certain number of things before forgetting takes place. Capacity = 7 plus our minus 2. Duration = 18-30 seconds. information is coded acoustically
LTM - Capacity and duration = unlimited. Information coded semantically. When info is recalled, it must move from LTM back to STM when we want to recall it (process called retrieval)
Evaluation - Supporting research evidence - supported by research studies that show that STM ands LTM are indeed qualitatively different. For example, Baddely found that we tend to mix up words that sounds similar when using out STMs. By we mix up words that have similar meaning when using our LTM. The strength of this is that the study clearly shows that coding in STM is acoustic and LTM is semantic. This supports the MSM's view that these two memory stores are separate and indeoendent. Further support is given by all the studies of coding, capacity and duration.
There is more than 1 type of STM. The MSM states that STM is a unitary store. However, evidence from people suffering with amnesia shows that this cannot be true. For example, Sallice and Warrington (1970) studied a patient known as KF. They found that KF's short term memory for digits was poor when they read them out to him. But his racal was much better when he was able to read the digits to himself. Further studies have shown that there could be another short term store for non-verbal sounds such as noises. The unitary STM is a limitation of the MSM because ressearch shows that at the very least there must be one short-term store to process visual information and other to process auditory information (WMM)
There is more than one type of reheasrsal - according to MSM, what matters in rehearsal is the mount of it that you do. So the more you rehearse information, the more likely you are to remember it . However, Craik and Watkins found that t what really matters about rehearsal is the type. Maitenance rehearsal does not transfer info into LTM, it just maintains STM. Elaborative rehearsal is needed for long-term storage. This happens when you link information to existing knowledge or thinking about the meaning of the information. This is a limitation because it is another research finding that cannot be explained by the model
There is more than one type of LTM. There is a lot of research evidence that LTM, like STM is not a unitary store. For example, Tulving stated that we have 3 different types of LTM; procedural, episodic and semantic
Artificial meterials used in studies to support MSM
Tulving proposed that there are 3 memory stores:
Episodic memory - ability to recall events from our lives
1) remember when it happened
2) remember places, people, objects etc.
3) make conscious effort to recall this memory
Semantic memory - Knowledge of th world, these memories are not time-stamped (do not remember when we learnt them)
Procedural memory - How we do things, skills, actions. Recall these without conscious awareness. Skills we find hard to explain to someone else
Evaluation - Clinical evidence - HM and Clive wearing are relevant here. Episodic memory in booth en were severely impaired as a consequence of amneissia. They had great difficulty recalling events that had happened to them in their pasts. But their semantic memories were relatively unaffected. Their procedural memories were also intact. This evidence supports Tulving's views that there are different memory stores in LTM. One store can be damaged but other stored are unaffected. This is also evidence that they are stored in different parts of the brain
Neuroimaging evidence - evidence from brain scan studies that different types of memory are stored in different parts of the brain. Tulving got his ppts to perform different tasks while their brains were scanned using a PET scanner. episodic and semantic = prefrontal cortex (left = semantic and right = episodic). Increases valdity of this study
Real-life applications - being able to identify different aspects of LTM allows psychologists to target certain kinds of memory in order to better people's lives. Belleville et al. (2006) demonstrated that episodic memories could be improved in older people who had a mild cognitive impairment. The trained participants performed bettie on a test of episodic memory after training than a control group. Episodic memory is the type of memory most often affected by mild cognitive imapirment, which highlights the benefit of being able to distinguish between types of LTM - because it enables specific treatments to be developed
Central executive - An attentional process that monitors incoming information, takes decisions and allocates slave systems to the tasks. Very limited processing capacity
Phonological loop - Deals with auditory information and preserved the order in which information arrives
PL divided into:
Phnological store - stores the words you hear
Articulatory process - allows maintenance rehearsal. The capacity of this loop is believed to be 2 seconds worth of what you can say
Visuo-spatial sketchpad - Stores visual and/or spatial information. Limited capacity (3 to 4 objects)
Divided into:
The visual cache - stores visual data
The inner scribe - records the arrangement of objets in the visual field
Episodic buffer - Added to the mosel by Baddeley in 2000. Temporary store for information, integrating the verbal, visual and spatial information processed by other stores and maintaining a sense of time-sequencing - eg. re wording events that are happening. Seen as storage component of central executive and limited capacity of about 4 chunks. Links working memory to LTM and wider cognitive processes such as perception
When two pieces of information conflict with each other, resulting in forgetting one or both memories
Proactive interference - occurs when an older memory intereres with a newer one
Retroactive interference - when a newer memory interferes with an older one
Effects of similarity - interference is worse when memories or learning as similar
Procedure - McGeoch and McDonald studied retroactive interference by changing the amount of similarity between two sets of material. Ppts had to learn a list of 10 words until they could recall then 100% accurately. They then learnt a new list of words. There were 6 groups of ppts who had to learn different types of lists:
Group 1 - synonyms
Group 2 - antonyms
Group 3 - words unrelated to the original ones
Group 4 - consonant syllables
Group 5 - three-digit numbers
Group 6 - no new list
Findings - When ppts then recalled the original list of words, their performance depended on the nature of the 2nd list. The most similar material produced the worst recall. Therefore, interference is strongest when the memories are similar.
Evaluation -
People may forget information due to insufficient cues. When info is initially placed in memory, associated cues are stored at the same time
Retrieval failure - not being able to access memories that are there
Encoding specificity principle - Tulving (1983) reviewed research into retrieval failure and discovered a consistent pattern to the findings. The encoding specificity principle states that if a cue is to help us recall information it has to be present at encoding and at retrieval. If cue available at encoding and retrieval are different, there will be some forgetting
Context-dependent forgetting - Godden and Baddeley (1975)
Procedure - divers learnt a list of words wither underwater or on land. 4 conditions
1) Learn on land, recall on land
2) Learn on land, recall underwater
3) Learn under water, recall underwater
4) Learn underwater, recall on land
Findings - Accurate recall was 40% lower in the non-matching conditions. The external cues at learning were different to the ones at recall so retrieval failure took place
State-dependent forgetting - Carter and Cassaday (1998) - Gave antihistamine drugs to ppts --> made them slightly drowsy. Ppts had to learn list of words and passages in 4 conditions
1) Learn on drug, recall on it
2) Learn on drug, recall when not on it
3) Learn not on drug, recall when on it
4) Learn not on drug - recall when not to it
Findings - In conditions where there was a mismatch between internal state at learning and recall, performance on memory test was significantly worse. Cues absent = more forgetting
Leading Q's - Loftus and Palmer (1974) arranged for pmts to watch film clips of car accidents and then gave them questions about the accident changing the verb used each time (smashed, collided, bumped, hit)
Findings - The mean estimate for each ppts group. The verb contacted resulted in a mean estimate of 31.8moh. For the verb smashed the mean was 40.5mph. The leading question biased the eye witness recall of an event
Why do leading Q's affect EWT?
The response-bias explanation suggests that the wording of the question has no real effect on the ppts memories but just how they decide to answer. Loftus and Palmer conducted a second experiment that supported the substitution explanation - the wording of a leading question study cages the ppts memory of the film clip. This was demonstrated because ppts who originally heard 'smashed' later were more likely to report seeing broken glass (there was none) than those who heard 'hit'
Post-event discussion - when co-witnesses to a crime discuss it with each other their EWT may become contaminated
Procedure: Fiona Gabbert and her collegues (2003) studied ppts in pairs. Each ppt watched a video of the same crime, but filmed from different points of view. This meant that each ppt could see elements in the vent that the other could not. Both ppts then discussed what they had seen before individually completing a test of recall
Findings - the researchers found that 71% of the ppts mistakenly recalled aspects of the event that they did not see in the view, but had picked up in discussion. In the control group where there was no discussion, this did not happen. Gabbert et. al concluded that witnesses either go along with each other to gain social approval or because the other witnesses are right and they are wrong. They called this phenomenon memory conformity
Anxiety has a negative effect on recall - creates physiological arousal in the body which prevents us paying attention to important cues so recall is worse
Weapon effect
Johnson and Scott (1976) led ppts bro believe they were going to be taking part in a lab study. While seated in the waiting room, ppts heard in argument I'm the next room. In low-anxiety condition s msn then walked through the waiting room carrying a pen with grease on his hands. Other ppt heard the same argument, but this time accompanied by the sound of breaking glass. A man walked out of the room holding a paper knife covered in blood (high anxiety condition)
Findings - Ppts later picked out the man from a set of 50 photos; 49% of the ppts who had seen the man carrying the pen were able to identify him. The corresponding figure for the man holding the knife was just 33%. The tunnel theory of memory argues that a witnesses attention narrows to focus on a weapon, because it is a source of anxiety
Anxiety has a positive effect on recall - The flight or fight response is triggered which increases our alertness and improves our memory of the event as we become more aware of the cues in the situation
Procedure - Yuille and Cutshall (1986) conducted a stud 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 4-5 months after the incident and these were compared with the original interviews made at the time of the shooting. Accuracy was determined by the number od details given in each account . The witnesses were also asked to rate how stressed they felt at the time of the incident using a 7 point scale, and asked if they had an emotional problems since the event
Findings - the witnesses were very accurate in their accounts and their was little change in the amount of accuracy after 5 months - though some details were less accurate . Those who reported the highest levels of stress were most accurate
Explaining contradictory findings - according to Robert Yerkes and John Dodson (1908) the relationship between emotional arousal and performance looks like ann inverted U. Lwer levels of anxiety produce lower levels of recall accuracy but memory becomes more accurate as levels of anxiety increases. This is only till optimal levels of anxiety are reached. This is the point of max accuracy, after this recall accuracy declines
Report everything - include very detial of the event, even if it is irrelevent or they do not feel confident about it
Reinstate the contecxt - return to the original crime scene in their mind and imagine the environment and their emotions . This is related to context-dependant forgetting
Reverse the order - to prevent people reporting their expectations of how the event must have happened rather than the actual events. It also prevents dishonesty
Change the perspective - Recvall the incident from other people's perspectives . This is done to disrupt the effect expectations and schema on recall
The enhanced cognitive interview - Fisher at. al (1987) developed some additional elements of CI to focus on the social dynamics of the interaction. For example the interviewer needs to know when to establish eye contact and when to relinquish it. It also includes ideas such as reducing eye witness anxiety, minimising distratcions, getting the witness to speak slowing and asking open-ended questions
Evaluation -
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Evaluation - Support for the WMM comes from Shallice and Warrington's (1970) case study of patients KF had poor STM ability for verbal information but could process visual information normally presented visually i.e had difficulty with sounds but could recall letter and digits. This suggests that just his phonological loop had been damaged leaving other areas of memory intact. This supports the existence of a separate visual and acoustic store. However, evidence from brain-damaged patients may not be reliable because it concerns unique cases with patients who have traumatic experiences Dual task performance - Support the separate existence of the visa-spatial sketchpad