Memory Flashcards
Two types of memory;
- STM
- LTM
STM = limited capacity memory store > coding is acoustic (sounds), capacity is between 5 and 9 items on average, duration is between 18 and 30 seconds
LTM = permanent memory store > coding is semantic (meaning), unlimited capacity and can store memories up to a life time
Coding
Coding = format in which information is stored in the various memory stores > process of converting information from one to another is called coding
Baddeley (1966) > gave lists of words to four different groups of participants
Group 1 = acoustically similar > words sounded similar
Group 2 = acoustically dissimilar > words sounded different
Group 3 = semantically similar > words with similar meanings
Group 4 = semantically dissimilar > words with different meanings
Results
- when testing STM recall = participants were asked to recall the original words in the correct order immediately after hearing them > they tended to worse on acoustically similar words
- when testing LTM recall = participants were asked to recall the list of words after a time interval of 20 minutes > they tended to do worse on semantically similar words
Capacity
Capacity = amount of information that can be held in a memory store
Jacobs (1887) = developed a technique to measure digit span - read out four digits and asked the participants to recall these in the correct order > discovered that the mean span for digits across all participants was 9.3 items on average & mean span for letters was 7.3
Span of memory and chunking = Miller (1956) noted that things came in sevens > suggested that the span of STM is about 7 items (plus or minus 2)
Duration
Duration = length of time information can be held
Duration of STM = Peterson & Peterson (1959) > gave 24 students a consonant syllable to remember and 3-digit number > they were told to count backwards from this 3-digit number - on each trail they were told to stop after a different amount of time - 3, 6. 9, 12, 15 or 18 seconds > students recalled on average about 80% of the syllables correctly with a 3-second interval > average recall after 18 seconds fell to 3% > suggests duration of STM without rehearsal is about 18 to 30 seconds
Duration of LTM = Bahrick et al. (1975) > studied 392 American participants aged between 17 and 74 > obtained their high school yearbooks and tested recall in various ways - 1. Photo recognition test consisting of 50 photos from the participants yearbook & 2. Free recall test where participants had to recall all the names of their graduation class - results showed participants tested within 15 years of graduation were about 90% accurate in photo recognition - after 48 years, recall declined to about 70% > Free call was less accurate - after 15 years, this was about 60% accurate dropping to 30% after 48 years > Shows LTM can last a very long time
Evaluation of coding, capacity and duration
- Baddeley’s study used artificial stimuli rather than meaningful material > word lists had no personal meaning to participants > this means we should be cautious about generalising the findings to different kinds of memory tasks > For example, when processing more meaningful material, people may use semantic coding even for STM tasks > suggests findings may have limited application
- Jacobs study was conducted a long time ago > early research in psychology lacked adequate control - for example, some participants may have been distracted while they were being tested so they did not perform as well as they might > this would mean the results may not be valid because there were confounding variables that were not controlled > shows it lacks validity
- Millers research may have overestimated capacity of STM > For example, Cowan (2001) reviewed other research and concluded that the capacity of STM was only about four chunks - suggests that the lower end of Millers estimate (five items) is more appropriate than seven items
- Peterson and Peterson’s study has artificial stimuli > trying to memorise consonant syllables does not reflect most real-life memory activities where what we are trying to remember is meaningful > so it can be argued that this study lacks external validity
+ Bahrick et al.’s study has high external validity > real-life meaningful memories were studied > when lab studies were done with meaningless pictures to be remembered, recall rates were lower > the downside of such real-life research is confounding variables are not controlled, such as the fact that Bahrick’s participants may have looked at their yearbook photos and rehearsed memories over time
The multi-store model of memory (MSM)
Proposed by Atkinson and Shiffrin (1968) - representation of how memory works in terms of three stores called sensory register, short-term memory (stm) and long-term memory (ltm) > describes how information is transferred from one store to another, how it is remembered and forgotten
Sensory register (SR) = memory store for each of our five senses
- A stimulus from the environment will pass into the sensory register > there are two main stores: iconic sensory register - coding is visual and echoic sensory register - coding is acoustic
- Capacity of the sensory register is high (millions of receptors)
- Duration is very brief as information lasts for less than half an second
- Little of what goes into the sensory register passes further into the memory system - needs attention paid to it
Short-term memory (STM) = is a limited capacity and duration store
- Capacity is between 5 and 9 items before some forgetting occurs
- Duration is about 18 to 30 seconds unless the information is rehearsed
- Coding is acoustic
- Maintenance rehearsal occurs when we repeat material to ourselves > information can be kept in our STM’s as long as we rehearse it > if we rehearse it long enough, it will pass into LTM
Long-term memory (LTM) = a permanent memory store for information that has been rehearsed for a prolonged time
- When we want to recall materials stored in LTM it has to be transferred back to STM by a process called retrieval
- Duration is potentially up to a lifetime
- Capacity is potentially unlimited
- Coding tends to be in terms of meaning - semantic
Evaluation of the multi-store model of memory
+ Supported by research which shows STM and LTM are different - For example, Baddeley found we tend to mix up words that sound similar when using our STM’s but we mix up words that have similar meanings in our LTMs > this shows that coding in STM is acoustic and in LTM semantic > supports the stores are different and are separate and independent
- Evidence suggests there is more than one type of STM - model states STM is a unitary store but evidence from people suffering from a clinical condition called amnesia shows that this cannot be true > For example, Shallice and Warrington (1970) studied a patient with amnesia known as KF > found KF’s short-term memory for digits was poor when he read them outloud but better when he read them to himself > therefore, the unitary STM store is a limitation as research shows there must be one short-term store to process visual information and another one to process auditory information > working memory model is a better explanation for this finding because it includes separate stores
- Model only explains one type of rehearsal - Craik and Watkins (1973) discovered there are two types of rehearsal > maintenance rehearsal is described by the model but this does not transfer information into LTM, it just maintains it in STM > Elaborative rehearsal is needed for long-term storage > serious limitation because it is another finding which cannot be explained by the model
- Research studies supporting the model use artificial materials > Researchers often asked participants to recall digits, letters and words which have no meaning in everyday life > suggests the model lacks external validity as the research findings reflect how memory works with meaningless material in lab testing but does not reflect how memory mainly works in everyday life
- Model oversimplifies LTM > there is research evidence that LTM is not a unitary store > we have one memory store for memories of facts about the world (semantic) and a different one for memories of how to ride a bike (episodic) > model does not reflect these different types of LTM
Types of long-term memory (LTM)
Tulving (1985) proposed there are three types of LTM stores, containing different types of information > episodic memory, semantic memory and procedural memory
Episodic memory = long-term memory store for personal events > episodic memories are time-stamped - you remember when they happened > involve several elements - people, objects, places and behaviours > you have to make a conscious effort to recall them
Semantic memory = long-term memory store for our knowledge of the world > includes facts and our knowledge of what words and concepts mean > it is less personal and more about the knowledge we all share
Procedural memory = long-term memory store for our knowledge of how to do things > includes our memories of learned skills and actions > we recall these memories without making a conscious or deliberate effort
Evaluation of types of long-term memory
+ Episodic memory supported by evidence of HM and Clive Wearing > their episodic memory was severely impaired as a consequence of amnesia > they had great difficulty recalling events that has happened to them in their past but their semantic memories were unaffected and their procedural memories are also intact > evidence supports Tulving’s view that there are different memory stores in LTM > one store can be damaged but the others are unaffected
+ Brain scan studies shows that there are different LTM stores > Tulving et al. (1994) got participants to perform various memory tasks while their brains were scanned using a PET scanner > found that episodic and semantic memories were both recalled from an area of the brain known as the prefrontal cortex which is divided in two, one on each side of the brain > the left prefrontal cortex was involved in recalling semantic memories and episodic memories were recalled from the right prefrontal cortex > shows a physical reality in the brain to different types of LTM, confirmed in many research studies supporting its validity
+ Identifying different LTM stores has real-life applications > Belleville et al. (2006) demonstrated that episodic memories could be improved in older people who had a mild cognitive impairment > trained participants performed better on a test of episodic memory after training than a control group > this highlights the benefit of distinguishing between different types of LTM because it enables specific treatments to be developed
- There are problems with clinical evidence > HM and Clive Wearing have provided a lot of useful information about what happens when memory is damaged > this has helped researchers to understand how memory is supposed to work normally > but such clinical studies are not perfect as there is a lack of serious control of different variables in clinical studies > it is difficult to generalise from these case studies to determine the exact nature of LTM
The working memory model (WMM)
Working memory model (WMM) = a representation of short-term memory - it is an explanation of how STM is organised and how it functions - consists of four main components; central executive, phonological loop, visuo-spatial sketchpad and episodic buffer
Central executive (CE) = coordinates activity of the three subsystems in memory - it is an attentional process that monitors incoming data, makes decisions and allocates slave systems to tasks & has a very limited processing capacity
Phonological loop (PL) = processes information in terms of sound > first slave system which deals with auditory information and preserves the order in which the information arrives > subdivied into; phonological store - which stores the words you hear and the articulatory process - which allows maintenance rehearsal
Visuo-spatial sketchpad (VSS) = second slave system which processes visual and/or spatial information in a mental space often called our ‘inner eye’
Episodic buffer (EB) = third slave system added to the model by Baddeley in 2000 which brings together material from other subsystems into a single memory - also provides a bridge between working memory and long-term memory
Evaluation of the working memory model (WMM)
+ Case of KF supports the separate STM stores > After KF suffered brain damage, he had poor STM ability for verbal information but could process visual information > this suggests his phonological loop had been damaged leaving other areas of the brain intact - this supports the existence of a separate visual and acoustic store
+ Dual task performance studies support the VSS > Baddeley et al. (1975) showed that participants had more difficulty doing two visual tasks than doing both a visual and verbal task at the same time > this increased difficulty because both visual tasks compete for the same slave system, whereas when doing both a visual and verbal task, there is no competition > this means there must be a separate slave system that processes visual input
+ Word length effect supports the phonological loop > Baddeley et al. (1975) found people have more difficulty remembering a list of long words than short words > this is known as the word length effect > this is because there is limited space for rehearsal in the articulatory process - the word length effect disappears if a person is given an articulatory suppression task - this is a repetitive task that ties up the articulatory process
- There is a lack of clarity over the central executive - cognitive psychologists suggest this component of the model is unsatisfactory and does not really explain anything > the central executive should be more clearly specified than just being simply ‘attention’ > some psychologists believe it may consist of separate components > this means the WMM has not fully been explained
Explanations for forgetting; Interference
Interference theory = occurs when two pieces of information conflict with each other, resulting in forgetting one or both
Types of interference;
- Proactive interference = forgetting occurs when older memories disrupt the recall of newer memories
- Retroactive interference = forgetting occurs when newer memories disrupt the recall of older memories already stored
Interference is worse when memories are similar
Effects of similarity study by McGeoch and McDonald (1931)
Procedure = Studied retroactive interference by changing amount of similarity between two sets of materials > participants had to learn a list of 10 words until they could remember them with 100% accuracy > then they had to learn a new list, each group had to learn a different list;
Group 1; words had the same meanings as the originals
Group 2; words had the opposite meanings to the originals
Group 3; words unrelated to the original
Group 4; nonsense syllables
Group 5; three-digit numbers
Group 6; no new list - participants rested (control group)
Findings =
- Performance of participants depended on the nature of the list - the most similar material produced the worst recall
- When participants were given different material, such as three-digit numbers, the mean number of items recalled increased
- This shows interference is the strongest when the memories are similar
Evaluation for explanations of forgetting; interference
+ Evidence from lab studies consistently demonstrates interference in memory - for example, the research by McGeoch and McDonald on the effects of similarity > most of these studies show that both types of interference are very likely to be common ways we forget information from LTM > this is a strength because lab experiments control the effects of extraneous variables and gives us the confidence that interference is a valid explanation
+ Real-life studies have supported the interference in memory > Baddeley and Hitch (1977) wanted to find out if interference was a better explanation for forgetting > they asked rugby players to recall the names of teams they had played so far in that season > results showed accurate recall did not not depend on how long ago the match took place but more importantly, was the number of games they played in the meantime > this study shows that interference explanations can apply to at least some everyday situations
- Research uses artificial materials - the stimulus material used in most studies are lists of words which is different from things we remember in everyday life > use of artificial materials makes interference much more likely in the lab > it may not be a likely cause of ‘everyday’ forgetting
- Interference effects may be overcome using cues - Tulving and Psotka (1971) gave participants five lists of 24 words, each organised into six categories > recall was about 70% for the first list but this fell as each list was learned most likely due to interference > However, when given a cued recall test, recall rose again to 70% > the memory of the words were stored in LTM but interference prevented access to them > when given a cue, it was easier to access the forgotten words
- Limitation of research is the time allowed between learnings - time periods between learning lists of words and recalling them are quite short in lab studies > a participant may learn two lists of words within 20 minutes > this does not reflect how we learn and remember things in real-life > so conclusions generated from research into forgetting in LTM may not generalise outside the lab
Explanations for forgetting; Retrieval failure
Retrieval failure theory = a form of forgetting which occurs when we do not have the necessary cues to access memory - 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
Encoding speciality principle (ESP) = Tulving (1983) reviewed research into retrieval failure and discovered a consistent pattern to findings - stated that if a cue is to help us recall information it has to be present in encoding (when we learn the material) and at retrieval (when we are recalling it) > the closer the retrieval to the original cue, the better the cue works > some cues have meaning linked to memory and some cues have no meaningful link (context-dependent forgetting and state-dependent forgetting)
Context-dependent forgetting = when memory is dependent on an external/environmental cue
Godden and Baddeley (1975) carried out a study with deep sea divers working underwater
- Diver’s learnt a list of words either underwater or on land > created four conditions
1. Learn on land - recall on land
2. Learn on land - recall underwater
3. Learn underwater - recall on land
4. Learn underwater - recall underwater
Findings = when the environmental contexts of learning and recall did not match, accurate recall was 40% lower than when they did match & when the external cues available at learning were different from the ones at recall, this led to retrieval failure due to lack of cues
State-dependent forgetting = when memory is dependent on an internal cue
Carter and Cassaday (1998) gave anti-histamine drugs to their participants which caused them to feel slightly drowsy > creates an internal physiological state different from the normal state of being awake and alert > participants had to learn list of words and passages and then recall the information creating conditions;
1. Learn on drug - recall when on drug
2. Learn on drug - recall when not on drug
3. Learn not on drug - recall when not on drug
4. Learn not on drug - recall when on drug
Findings = When there was a mismatch between internal state of learning and recall, performance on the memory test was significantly worse
Evaluation for explanation of forgetting; retrieval failure
+ There is supporting evidence of the explanation > studies by Godden and Baddeley and Carter and Cassaday are two examples of research > this evidence increases the validity of the explanation > especially true when retrieval failure occurs in real-life situations as well as in highly controlled lab conditions
- Baddeley (1997) argues that context effects are actually not very strong, especially in real-life > learning something in one room and recalling it in another is unlikely to result in much forgetting because the environments are not different enough > this means that real-life applications of retrieval failure due to contextual cues don’t actually explain much forgetting
- Context effects only occur when memory is tested in certain ways > Godden and Baddeley (1980) replicated their underwater experiment but used a recognition test instead of recall > participants had to say whether they recognised a word read to them from the list instead of retrieving it themselves > when recognition was tested, there was no context-dependent effect and performance was the same in all four conditions > limitation because it means the presence or absence of cues only affects memory when you test it in a certain way
- There are problems with the encoding speciality principle > it is not testable > when a cue produces successful recall of a word, we assume the cue must have been present at the time of learning > if a cue does not result in a successful recall, then we assume that the cue was not encoded at the time of learning > but there is no way to independently establish whether or not the cue has really been encoded
