Memory Flashcards
Define coding.
The format in which information is stored in the various memory stores.
Define capacity.
The amount of information that can be held in a memory store.
Define duration.
The length of time information can be held in memory.
Define short term memory (STM).
The limited-capacity memory store.
Coding is mainly acoustic (sounds).
Capacity is between 5 and 9 items on average.
Duration is between about 18 and 30 seconds.
Define long term memory (LTM).
The permanent memory store.
Coding is mainly semantic (meaning).
Capacity is unlimited.
Duration is for up to a lifetime (it can store memories for up to a lifetime).
Describe research on coding.
Once information gets into the memory system, it is stored in different formats, depending on the memory store. The process of converting information from one form to another is called coding. Alan Baddeley (1966a, 1966b) gave different lists of words to four groups of participants to remember:
- 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 that all had different meanings
Participants were shown the original words and asked to recall them in the correct order. When they had to do this recall task immediately after hearing it (STM recall), they tended to do worse with acoustically similar words.
If participants were asked to recall the word 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.
Describe research on capacity.
Digit span
Joseph Jacobs 1887 developed a technique to measure digit span. The researcher gives, for example, 4 digits and then the participant is asked to recall these in the correct order out loud. If this is correct the researcher reads out 5 digits and so on until the participant cannot recall the order correctly.
This determines the individual’s digit span.
Jacobs found that the mean span for digits across all participants was 9.3 items.
The mean span for letters was 7.3
Describe research on capacity.
Span of memory and chunking
George Miller 1956 made observations of everyday practice. He noted that things come in sevens, this suggests that the span or capacity of STM is about 7 items (plus or minus 2). However, Miller also noted that people can recall 5 words as well as they can recall 5 letters. They do this by chunking - grouping sets of digits or letters into units or chunks.
Describe research on duration.
STM
Margaret and Lloyd Peterson 1959 tested 24 undergraduate students. Each student took part in eight trials, a trial being one test.
On each trial the student was given a constant syllable (a trigram like YCG) to remember and was also given a 3-digit number. The student was then asked to count backwards from that 3-digit number until told to stop.
This counting backwards was to prevent any mental rehearsal of the constant syllable (which would increase the student’s memory for the constant syllable).
One each trial they were told to stop after a different amount of time - 3, 6 , 9, 12, 15 or 18 seconds. This is called the retention interval. Their findings were that the percentage of correct responses decreased as the retention interval (seconds) increased.
It suggests that STM may have a very short duration, unless we repeat something over and over again (verbal rehearsal).
Describe research on duration.
LTM
Harry Bahrick et al 1975 studied 392 participants from the American state of Ohio who were aged between 17 and 74. High school yearbooks were obtained from the participants or directly from some schools.
Recall was tested in various ways;
- photo-recognition test
test consisted of 50 photos, some from the participant’s high school yearbook
- free recall
test where participants recalled all the names of their graduating class.
Participants who were tested within 15 years of graduation were about 90% accurate in photo recognition. After 48 years, recall decline to about 70% for photo recognition.
Free recall was worse than recognition, after 15 years this was about 60% accurate, dropping to 30% after 48 years.
This shows that LTM can last a very long time indeed.
Evaluate Baddeley’s study on coding.
- Baddeley’s study used artificial stimuli rather than meaningful material, the word list had no personal meaning to participants. This means we should be cautious about generalising the findings to different kinds of memory task. When using more meaning information, people may use semantic coding even for STM tasks. This suggests the findings have limited application.
Evaluate Jacob’s study on capacity (digit span).
- Jacob’s study was conducted a long time ago, early research in psychology often lacked adequate control. For example, 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 as there were confounding variables that were not controlled.
However, the results of this study have been confirmed in other research, supporting its validity.
Evaluate Miller’s study on capacity (span of memory and chunking).
- Miller may have overestimated the capacity of STM. Cowan 2001 reviewed other research and concluded that the capacity of STM was only about four chunks.
This suggests that the lower end of Miller’s estimate (5 items) is more appropriate than 7 items.
Evaluate Peterson and Peterson’s study on duration of STM.
- Peterson and Peterson used stimulus material that was artificial. This is a limitation as trying to memorise constant syllables does not reflect most real-life memory activities where what we are trying to remember is meaningful. So this study might lack 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 alternative explanation is that the information in STM is displaced - STM has a limited capacity and any new information will push out what is currently there. In the study by Peterson and Peterson participants counted down during the retention interval.
Evaluate Bahrick’s study on duration of LTM.
- Bahrick et al’s study has high 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 1967).
The downside of such real-life research is that confounding variables are not controlled, such as the fact that Bahrick’s participants may have looked at their yearbook photos and rehearsed their memory over the years.
Who designed the multi-store model (MSM)?
Richard Atkinson and Richard Shiffrin
What is the 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 forgotten.
What is the 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 lasts for a very short time (less than half a second).
What does the multi-store model describe?
Richard Atkinson and Richard Shiffrin’s (1968, 1971) multi-store model describes how information flows through the memory system. The model suggests that memory is made up of three stores linked by processing.
What is the actual model of the MSM?
Stimulus from the environment —- Sensory register (Iconic, echoic) —- STM – (prolonged rehearsal) – LTM.
(Response)
LTM is transferred back to STM by retrieval.
STM is kept in STM by maintenance rehearsal.
Describe sensory register in terms of coding, capacity and duration.
A stimulus from the environment will pass into the sensory registers along with lots of other sights, sounds, smells and so on. So this part of memory is not one store but several, one for each of our five senses. The two main stores are called iconic memory (visual information is coded visually) and echoic memory (sound - or auditory - information is coded acoustically).
Material in sensory registers lasts only very briefly - the duration is less than half a second. The sensory registers have a high capacity, for example over one hundred million cells in one eye, each storing data.
Very little of what goes into the sensory register passes further into the memory system. But it will if you pay attention to it. So the key process is attention.
Describe STM in terms of coding, capacity and duration.
STM is what is known as a limited capacity store, because it can only contain a certain number of ‘things’ before forgetting takes place. The capacity of STM is on average somewhere between 5 and 9 items of information (7+/- 2). Research suggests that it might be more like 5 rather than 9.
Information in STM is coded acoustically and lasts about 30 seconds unless it is rehearsed.
Maintenance rehearsal occurs when we repeat (rehearse) material to ourselves over and over again. We can keep the information in our STMs as long as we rehearse it. If we rehearse it long enough, it passes into the LTM.
What is maintenance rehearsal?
Maintenance rehearsal occurs when we repeat (rehearse) material to ourselves over and over again.
Describe LTM in terms of coding, capacity and duration.
LTM is potentially the permanent memory store for information that has been rehearsed for a prolonged time. Psychologists believe that its capacity is unlimited and can last very many years. E.g. Bahrick et al found that many of their participants were able to recognise the names and faces of their school classmates almost 50 years after graduating.
LMT tends to be coded semantically (in terms of meaning).
Although this material is stored in LTM, when we want to recall it, it has to be transferred back into STM by a process called retrieval.
According to the MSM, this is true of all our memories. None of them are recalled directly from LTM.
Evaluate the multi-store model of memory.
- supporting research evidence, MSM is supported by research studies that show that STM and LTM are qualitatively different. For example, 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 this study is that it clearly shows that coding in STM is acoustic and in LTM it is semantic. So they are different, and this supports the MSM’s view that these two memory stores are separate and independent. Further support is given by all the studies of coding, capacity and duration we encountered in the previous spread.
- there is more than one type of STM, MSM states that STM is a unitary store. However, evidence from people suffering from a clinical condition called amnesia shows that this cannot be true. E.g. Shallice and Warrington 1970 studied a patient with amnesia known as KF. They found that KF’s short-term memory 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. This and other studies of people with amnesia showed that there could be another short-term store for non-verbal sounds. 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 to process auditory information.
- there is more than one type of rehearsal, according to 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 1973 found that this prediction is wrong, what really matters is the type of rehearsal. They discovered that there are 2 types of rehearsal, maintenance rehearsal (this doesn’t transfer information into LTM, it just maintains it in the STM) and elaborative rehearsal - this is needed for long-term storage. This is when you link the information to your existing knowledge, or you think about what it means. This is a limitation because the MSM cannot explain this.
- artificial materials, a lot of research studies use artificial materials when testing memory, these have no meaning and therefore lack external validity.
- there is more than one type of LTM, there is a lot of research evidence that LTM is not a unitary memory store, these different types of memory cannot be explained by the MSM.
What is the case study 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 to be central to memory function. When his memory was assessed in 1955, he thought the year was 1953, and that he was 27 years old (he was actually 31). He had very little recall of the operation and he could not remember speaking with someone just an hour earlier.
His LTM was tested over and over again but never improved with practice. He would read the same magazine repeatedly without remembering it. He couldn’t recall what he had eaten earlier the same day. However, despite all of this, he performed well on tests of immediate memory span, a measure of STM.
What did Endel Tulving 1985 suggest about LTM?
Endel Tulving 1985 was one of the first cognitive psychologists to realise that the multi-store model’s view of LTM was too simplistic and inflexible. Tulving proposed that there are in fact three LTM stores, containing different types of information. They were episodic memory, semantic memory and procedural memory.
What is episodic memory?
Episodic memory is our long-term memory store for personal events, it refers to our ability to recall events from our lives. These memories are time-stamped, you remember when they happened. They also include several elements that are interwoven to produce a single memory. With episodic memory you have to make a conscious effort to recall them, you will be able to do so quickly but are still aware that you are searching for your memory of what happened.
What is semantic memory?
Semantic memory contains our knowledge of the world, this includes facts, but in the broadest possible sense. This type of memory is linked to an encyclopedia and a dictionary.
These memories are not timestamped, we usually don’t remember when we first learned about something. It is less personal and more about facts we all share. It contains an immense collection of material which is constantly being added to. These memories usually also need to be recalled deliberately.
What is procedural memory?
Procedural memory is our memory for actions, skills or basically how we do things. We can recall these memories without conscious awareness or a great deal of effort.
Evaluate types of LTM.
- clinical evidence, case studies of HM (Henry Molaison) and Clive Wearing show support. 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, meaning they still understood the meaning of words. Their procedural memories were also intact. This evidence supports Tulving’s view that there are different memory stores in LTM. One store can be damaged but other stores are unaffected, this makes is clear that there are different types of memory stored in different parts of the brain.
- neuroimaging evidence, there is evidence from brain scan studies that different types of memory are stored in different parts of the brain. Tulving et al 1994 got their participants to perform various memory tasks while their brains were scanned using a PET scanner. They found that episodic and semantic memories were both recalled from an area of the brain known as the prefrontal cortex. This area is divided in two, one on each side (hemisphere) of the brain. The left prefrontal cortex was involved in recalling semantic memories while episodic memories were recalled from the right prefrontal cortex. This supports the view that there is a physical reality to the different types of LTM. It has also been confirmed many times in later research studies, further supporting the validity of this finding.
- 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 better 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 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 (evidence from case studies), clinical studies often lack control from of all sorts of different variables. There should also be caution when generalising findings to the wider population because these people have suffered trauma.
- Three or two types of LTM, Cohen and Squire 1980 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 call declarative memory (memories that can be consciously recalled). This makes procedural memory non-declarative.
Describe the case study of Clive Wearing.
Clive Wearing suffers from a severe form of amnesia that resulted from a viral infection that attacked his brain, damaging the hippocampus and associated areas. Before this infection Clive was a world-class musician and he can still play the piano brilliantly and conduct a choir but he can’t remember his musical education. He can remember some other aspects of his life before the infection, but not others. For example, he knows that he has children from an earlier marriage, but cannot remember their names. He recognises his second wife, Deborah, and greets her joyously every time they meet, believing he has not seen her in years, even though she may have just left the room for a few minutes.
What is declarative memory?
Memories that can be consciously recalled.
- Episodic memory
- Semantic memory
What is the working memory model (WMM) made up of?
Central executive Phonological loop Visuo-spatial sketchpad Episodic buffer (LTM - not exclusively WMM but included in diagram)
What is the working memory model?
The working memory model is an explanation of how one aspect of memory (STM) is organised and how it functions. The WMM is concerned with the part of the mind that is active when we are temporarily storing and manipulating information.
The WMM suggests that STM is a dynamic processor of different types of information using sub-units coordinated by a central decision-making system.
What is the central executive?
The central executive is an attentional process that monitors incoming data, makes decisions and allocates slave systems to tasks - the slave systems being the phonological loop, visuo-spatial sketchpad and episodic buffer.
The central executive has a very limited processing capacity.
What is the phonological loop?
One of the slave systems that deals with auditory information (coding is acoustic) and preserves the order in which the information arrives.
The PL is subdivided into:
- the phonological store, which stores the words you hear.
- the articulatory process, which 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 visuo-spatial sketchpad?
The second slave system is the visuo-spatial sketchpad. The VSS stores visual and/ or spatial information when required. It also has a limited capacity, which according to Baddeley 2003 is about three or four objects.
Logie 1995 subdivided the VSS into:
- the visual cache (which stores visual data)
- the inner scribe (which records the arrangement of objects in the visual field)
