Download The Cognitive Approach to Memory

1. The Cognitive Approach to Memory
Computer Analogy
Cognitive psychologists compare human memory to the processing of information in a computer; LTM
could be compared to a hard drive – the permanent storage of the system. Like a computer, we
process new information, and store it until needed. Using this analogy, the STM is more like your
computer’s processing power.
Models of memory often focus on processing and storage too. In the next section you will study two
models – the multi-store and working memory models – which both emphasise the way that
information can be processed and moved from one store to another, very like information being
processed and saved on a computer.
Schemas
Another useful concept from this approach is the schema, that is, a set of ideas and beliefs about
something that you have experienced. Cognitive psychologists thinks that long-term memories are
based on schemas, meaning that similar memories are stored together.
As our schemas are influenced by culture and expectations, people should remember things better if
they are consistent with a schema. This is exactly what was found by memory researchers Brewer and
Treyens (1981) who studied recall of objects in an office scene. However, in a similar study, Pezdek et
al (1989) directly compared schema-consistent and schema inconsistent items, and found that that
inconsistent items were better recalled. They concluded that this is due to more attention being given
to items that seem surprising or unusual during the process of encoding. Either way, it is apparent
that memory for objects is influenced by expectations from our schemas.
Evaluation of the Approach
There are considerable problems with the computer analogy. Unlike a hard-drive, the LTM does not
seem to have a limited capacity and memories can interfere with each other in a way that is very unlike
computer storage. In addition, memories are not recalled in a similar way to a computer – a computer
searches for files with no regard for meaning.
The concept of the schema seems to fit the evidence better, as human memory recalls things by
association, and successful retrieval can depend on context, as seen in the Brewer and Treyens study.
However, there is some contradictory evidence in the research into schemas, and the term ‘schema’
is not always used consistently in research. Fiske and Linville (1980) argue that overall, despite some
truth in the accusation that the term is imprecise, the benefits of schema theory outweighs its flaws.
It has also been applied to improve the understanding of eyewitness memory.
Key Study: Brewer and Treyens (1981): The Study of Schemas in Memory
Aim
The researchers conducted an experiment to determine what effect it had on memory if items were
consistent with a schema or not (i.e. they did or did not fit the context).
Method
This was a lab experiment, but quite an unusual one as the ‘lab’ had been set up to look like an office.
This small room was arranged with 63 carefully selected objects clearly on view. Some had been
chosen to fit the office schema (e.g. a phone) while others did not fit the schema – you would typically
not see them in an office (e.g. a brick or a picnic basket). Participants were told to wait in the room
until the experiment began and they did not realise that their recall of the objects was part of the
experiment. After 90 seconds, they were taken to another room and told to write down all of the
objects that they remembered seeing.
Findings
Brewer and Treyens found that the level to which items fitted the schema – that is, the extent to which
people would expect to see items such as a telephone, a notepad or a skull in a typical office – strongly
correlated with level of successful recall. The researchers concluded that the office schema was acting
as a retrieval cue. When people try to recall items, they mentally generate an image of a typical office
from their schema and this process reminds them of items that were at the scene.
Evaluation
This study was unusual in that it used a real-world context rather than pictures or objects on a screen,
and therefore, had higher ecological validity than other studies of its time. However, it is limited in
that the use of correlation cannot determine cause and effect. There is no control over what the
participants were doing while waiting in the room and it may be that they remembered some items
better than others just because they were easier to see or because they paid more attention to them.
Other research such as Pezdek et al (1989) has contradicted the study, finding that schemainconsistent items were better recalled.
**REMINDER**
Encoding is the process of getting new information into the memory. Some coding can be done
automatically, but other coding requires more attention and effort. Information has to be coded in
such a way that it is accepted into the memory system. What type of code is used in the encoding of
information to memory depends upon the properties of the stimulus and comes in three forms:
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acoustic - sound codes;
visual or imagery - pictures or images;
semantic - by meaning or words.
There is research going on at the fundamental level of the neuron - the basic unit of the nervous
system. Studies are attempting to code the memory trace or 'engram', as it has been named, which
refers to the physical change in the central nervous system that occurs as a result of experience.
Storage refers to the maintenance of information in the memory over time. Later models will show at
least three different types of storage compartments or structures with different capacities and
durations. Cognitive psychology calls these memory storage facilities sensory register, short-term
memory and long-term memory.
Rehearsal can help in the storage of memory. Simple repetition of information is known as
maintenance rehearsal, e.g. in a recall task, repeating words by sounding them to yourself. Elaborative
rehearsal is more complex and functions by linking the new information to existing information, e.g.
remembering the name of a man you have just been introduced to as John Parrot - you might think
he is like my Uncle John who keeps birds in cages…
Retrieval is getting information back out of the memory system through recall or recognition.
Some stimuli are very easy to recall, such as names of friends and family, and the retrieval process is
extremely fast. Other information takes much longer to retrieve and it is more apparent that there is
a search process occurring.
The above basic memory processes can be illustrated using the library model.
Imagine a library consisting of thousands of books and you want to find a particular book about organic
chemistry. All library books are given a unique numeric code when they are first stocked, which is part
of the Dewey Decimal System. The codes for the books are then indexed in files. The books are then
placed (stored) on the library shelves according to their Dewey number and subject matter (chemistry
in this case). If you wish to retrieve a particular book, you would go to the index file and look up the
Dewey number of your required book, then go to the appropriate shelf in the chemistry section. A
systematic approach such as the Dewey system leads to efficient location of books for quick retrieval.
The psychological assumption being made is that an efficient memory may work in a similar way.
Basic Memory Processes
Psychologists propose three basic processes for memory:
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encoding;
storage;
retrieval.
The above basic memory processes can be illustrated using the library model.
Imagine a library consisting of thousands of books and you want to find a particular book about organic
chemistry. All library books are given a unique numeric code when they are first stocked, which is part
of the Dewey Decimal System. The codes for the books are then indexed in files. The books are then
placed (stored) on the library shelves according to their Dewey number and subject matter (chemistry
in this case). If you wish to retrieve a particular book, you would go to the index file and look up the
Dewey number of your required book, then go to the appropriate shelf in the chemistry section. A
systematic approach such as the Dewey system leads to efficient location of books for quick retrieval.
The psychological assumption being made is that an efficient memory may work in a similar way.
Using models to explain memory
Because memory is a hypothetical construct, it does not exist in reality. This makes it difficult to
investigate. As a result, cognitive psychology uses models to illustrate how memory, perception,
thinking, etc. may work. Models can provide an illustrative approach which is more friendly to those
who are meeting the new ideas and theories for the first time. The model approach also lends itself
well to evaluation, either of the whole model or of the discrete parts.
1. Multi store model
The founder researchers for the multi store model were Atkinson and Shiffrin (1968). They proposed
that, in order for information to become lodged in memory, it must pass through three stores. The
diagram below summarises their ideas.
This diagram is very much a basic representation of the model. A fuller representation will develop as
we go deeper into the model, clarifying both the discrete parts and the various functions.
Sensory memory
No matter which model of memory is being discussed, it is agreed that the first part of our memory
process starts with stimuli from our environment which stimulate the sensory nerve cells responsible
for sight, touch, taste, etc.
In the multi store model, the sensory memory store initially deals with incoming signals. The
information passes into the sensory memory for a very short time - probably less than second. This is
comparable with a reflex and, therefore, some would argue that storage is not involved and thus it is
referred to as the Dual Store Model. The time in sensory memory is so short that it is difficult to
imagine how much processing occurs. Certain psychologists suggest that the sensory store acts as a
filter of the sensory stimuli, directing the resultant nerve signals from the various sensors into the
short term memory.
Imagine being in a completely dark room and asking someone to trace out a number using a torch so
that can recognise the number, which is known as the 'light dot' technique. Think about what would
be happening in the sensory memory store. You would have to remember the position of the light dot
at different times and combine them to produce an image of the number. Imagine if the trace was so
slow that you had forgot the position of the dot towards the start by the time that it reached its final
point. You may not then recognise the number. If the number being traced was 3 then, using the light
dot technique, the positions could be interpreted as an 8 instead. You may have seen this effect when
using some types of digital calculators.
Short-term memory
Research suggests that short term memory (STM) is more complex than sensory memory. Information
stays longer in the STM and there is also a bigger capacity for information. When you look up a new
telephone number and immediately punch it into the phone, you are probably using short term
memory - note that modern telephone numbers have 11 digits. That is a lot to remember in one go.
Imagine trying to retain the numbers of all your friends - this would be quite a feat.
Encoding, capacity and duration in STM
Encoding - Conrad (1964) suggests that all information that ends up in memory is coded acoustically,
using sound. Any visual information is transferred into acoustic codes - the coding process may be you
see a house, you say to yourself "house" and that implants the house in your memory.
Conrad showed participants strings of letters and asked them to recall them immediately. Mistakes
tended to involve replacing the correct letter, e.g. "C", with one that sounded similar, e.g. "P", "D" or
"T". The mistakes occurred even when the letters were presented visually, without vocalising them.
Shulman (1970) thought that STM encoded information using visual and semantic (meaning) codes.
Heyer and Barrett (1974) suggested that visual images that are difficult to code acoustically can be
stored in STM. It is now accepted that encoding in STM involves all three types of codes - acoustic,
visual and semantic. Possibly, acoustic coding is the most important, especially when we consider
rehearsal strategies.
Capacity - what is the capacity of short term memory? Howard (1983) coined the phrase the
immediate memory span for capacity - this was the maximum number of items that could be recalled
after one presentation.
A classic study was carried out by George Miller (1956) into memory capacity. Miller pointed out that
there was a magical number 7, plus or minus 2 items of information that could be processed through
STM. Miller was referring to chunks of information rather than discrete items.
Let's try and clarify this.
Example 1
Consider the following two strings of digits:
6192738 - this is seven discrete digits
9876 321 - these are the same digits but arranged/organised differently into two chunks 9876 and
321
The first series will be more difficult to remember than the second organised series. This is an example
of organising information into categories or chunks to improve the capacity of memory.
Millers '7 chunks' could be discrete digits, grouped digits, discrete letters, grouped letters etc. The
important issue here is that it did not matter the form of the information, digits, letters etc. - the key
is that the capacity was always about seven items.
Duration - short term memory is believed to hold information for about 15 to 30 seconds (Brown and
Peterson, 1959).
A procedure by Brown (1958) and Peterson (1959) was used to measure how long unrehearsed
information remained in STM. (An example of rehearsed information would be if you were asked to
remember and recall a series of words in a memory task and you were to repeat them to yourself after
seeing them until such point that you are asked to recall them. This is known as a rehearsal loop.)
Participants were presented with a group of letters, e.g. 'YFM', and asked immediately to count
backwards e.g. 754, 751, 748 etc., until a given signal, then the participants were asked to recall the
letters 'YFM'. The recall interval (time spent counting backwards) is varied from about 3 seconds to 25
seconds.
The diagram below provides an indication of the results (note that the data is adapted from Brown
and Peterson). Duration in STM appears to be about 18 seconds.
Brown and Peterson suggested that information that
is continually rehearsed can be stored in short term
memory indefinitely, but is lost as soon as rehearsal
is blocked.
Losing Information from STM
Why do we lose information from STM?
Chunking and rehearsal are two important ways of improving STM.
Three mechanisms are postulated:
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decay;
displacement;
interference.
Peterson and Peterson (1959) proposed that information decays (fades rapidly) in STM unless
rehearsal occurs.
Reitman (1974) suggested that the short duration time in STM is due to displacement. Imagine a
scenario where all sorts of information is queuing up in the STM store. Remember also that STM has
a limited capacity. Information in the queue is liable to be knocked out (displaced) by the incoming
new information.
The phrase "Mary is sad" would be lost or forgotten in the above example.
Existing information can interfere with new incoming information. Interference can block rehearsal
and we can imagine how this can have a significant effect on STM, which uses rehearsal as a strategy
for improving memory.
Long-term memory
Can you remember the following:
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what was on TV last night?
what you had for breakfast yesterday?
what you did last Friday?
what you did at your last birthday party?
what you did at your first day at school?
You will probably remember some details from most, or even all, of the above. You are using longterm memory (LTM) to do this. Information that remains in the brain for more than a few minutes
probably ends up in LTM or is lost. We will see later that the retrieval process for LTM is very
important, especially when we consider that a lifetime of information is stored there.
What are the features of long term memory in the multi store model?
As with STM, let us consider encoding, capacity, and duration with respect to long term memory and
then we will look at retrieval.
Encoding - as with much of the research in memory, there is not a definitive picture for LTM.
Debatably, the same three processing codes feature in LTM as in STM, but to different extents - the
codes are visual, acoustic and semantic. There is extensive research which suggests that semantic
coding is by far the most important in LTM. Acoustic coding is important in STM and in transferring
information from STM into the LTM by means of rehearsal strategies. Baddeley (1966) suggested that
coding in LTM was either procedural or declarative.
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Procedural coding deals with those skills and procedures that we do almost automatically driving a car, riding a bike, walking, swimming etc. Internalising by means of repetitive practice
is important in procedural memory. The more we practice using a calculator, the easier it
becomes to key in numbers or functions without consciously thinking about it. The process
becomes automatic.
Declarative coding is where we encode facts about our world to LTM using semantic and
episodic memory. Consider the following examples:
o My car is a Mazda 623 Atlantis.
o My previous house, which I left 17 years ago, was in Dumfries.
o I know that the word philosophy is spelt "PHILOSOPHY".
These are all examples of declarative memories, encoded and stored on the basis of semantic
memory. Declarative memories are often associated with particularly exciting, important,
emotional or traumatic events. Many people specifically remember exactly what they were
doing when the news came through about the Dunblane incident when children and teachers
were gunned down or when the planes crashed into the Twin Towers in New York. Do you
have any comparable memories?
Episodic coding is thus used to encode information about events to LTM - what the event was, when
it happened and what happened etc., e.g. I arranged to meet at my friend's house at noon yesterday
or I remember going to John's party last Tuesday. These are further examples of encoding, storing and
retrieving LTM using episodic memory.
Remember: semantics is about facts/words, episodic is about events.
We mainly encode to LTM on the basis of semantic memory.
Capacity - there appears to be no limit to the capacity of LTM, in which all of the memories of a lifetime
can be stored. There are recent suggestions that some memories may be passed on through our genes.
Human memory outstrips the memory system of the biggest, most efficient computer.
Duration - long term memory is relatively permanent or infinite.
Retrieval - often, the issue with memories in LTM is accessibility.
Imagine trying to retrieve items of information that have been coded and stored for many years
without use. As mentioned previously,an important feature of LTM is the retrieval process. Try to
imagine the awesome amount of information in LTM and yet we can retrieve items almost instantly.
This is an amazing feat which we take completely for granted.
How does retrieval occur?
Retrieval essentially involves recall or recognition of stored information in LTM. Recognition tasks are
easier than recall because they contain more cues.
Consider the following two questions.
1. Which of the following has the shortest duration?
a. Long term memory.
b. Short time memory.
c. Sensory memory.
d. Declarative memory.
2. What is the capacity of STM?
Question 1 could have been asked as "Which type of memory has the shortest duration?". By listing
the types, all we are asked to do is to 'recognise' the type.
Question 1 is therefore about recognising an answer from the cues provided.
Question 2, in comparison, is about recall.
Tulving (1973), as part of his Encoding Specificity Hypothesis, stated the following:
"Only that can be retrieved that has been stored, and how it can be retrieved depends on how it was
stored".
Let us pursue this line of thinking further. Remember the Library Model? The ease of finding a specific
book about chemistry in a library is very dependent on how the book was stored - if it is stored
alphabetically under the subject area then you would first check the subject list and look under "C"
for chemistry and go to the corresponding section of the library. You would then scan the books
alphabetical until you find the one that you are looking for. However, it is not as simple as that, as you
will have experienced if you have gone into a massive library where chemistry has many shelves of
books. You would need further clues to find your specific book, e.g. a sub-category of chemistry such
as "organic chemistry", the author, the Dewey code, even a piece of knowledge as simple as "is the
book a large tome or a paper back?". All the information would help you in your retrieval search.
Several factors can affect the retrieval process.
The difficulty in accessing a memory from LTM may involve the following:
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the distinctiveness of the memory relative to other LTM stored information;
how interconnected the memory is to other information and the quality of this
interconnectivity (similar to this is the concept of "depth of processing" in the Levels of
Processing Model);
the current state of the memory and the condition that existed when the memory was first
stored;
the frequency of access of that particular memory - the more a memory is recalled the easier
it becomes to recall again.
Remembering an incident, such as car crash, involves recalling facts, images and events. It also involves
the brain assimilating this information, other partial information, and logically organising all of this
into a memory of the incident. This process of memory reconstruction can be fraught with difficulties.
This section has been focussing on the multi store model of memory, essentially based around the
work of Atkinson and Shiffrin (1968). We have digressed at times to help explain the functioning of
the various stores in the model. How robust is the model?
In the world of psychology, there has been lots of support, with much empirical evidence, for the
model.
Glanzer and Cunitz (1966)
Their research was similar in methodology to Atkinson, using a free recall task but with an interference
prevention task given immediately after the last item on the word list. Under these conditions the
recency effect disappeared - the reason given suggested that the interference task dislodged the last
words from short term memory - the last words were no longer the most recent bits of information
entering the STM.
The hypothetical graph below illustrates results from such an experiment, showing quite clearly the
tailing off of the recency effect after about the 10th word.
Korsakoff's syndrome
Korsakoff's syndrome gives interesting physiological support for Atkinson and Shiffrin's multi-store
model of memory. Korsakoff's syndrome occurs with some chronic alcoholics when they decide to
give up drink. The sudden alcohol withdrawal can trigger Korsakoff's syndrome, where they exhibit
effective STM functioning, but impaired LTM. This suggests evidence for two separate memory stores,
such as STM and LTM. Korsakoff's syndrome can be avoided easily by taking vitamin supplements
during detoxification.
Limitations of the Model.
1. Many psychologists suggest that the model is too simple. Relatively speaking there has been
little research into LTM.
2. Studies have shown that rehearsal strategies between STM and LTM do not always lead to
storage.
3. De Groot (1966) - this was a study of expert chess players whose capacity for recalling chess
positions, as long as they fitted with the known rules, were exceptional, suggesting very
efficient STMs. However when the chess pieces were randomly arranged, recall was no better
than non-chess players. De Groot implies that expert chess players use chunking and gestalten
to aid STM, and that STM and LTM may not be so separate and distinct as the multi-store
model suggests.
Working memory model
The working memory model asserted by Baddeley and Hitch (1974) is a model of short term memory.
It is a more complex explanation of short-term memory, breaking it down into subsystems and a
central control system.
Many researchers refer to short-term memory as working memory. "Working" is meant in terms of
storing and processing information. Working memory is important in our everyday mental work such
as:
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remembering the names of people and where they live and work;
remembering telephone numbers;
booking and catching a train or bus;
playing a piano;
checking your change at the supermarket.
Some of these tasks involve visual images while others involve acoustic/sound stimuli, apparently in
quite complicated mental functioning. Working memory links the storage of information to the
ongoing mental activities. It is very useful in problem solving, allowing mental manipulation of
numbers or concepts.
Research work supporting the working memory model
The working memory model is supported by empirical evidence, in particular by Baddeley's own
research which suggests that the STM is complex and easier to accommodate in the working memory
model than in the multi store model. The working memory model can explain how we can do two
tasks at once if they involve different subsystems and why it is we have trouble with some tasks that
involve the same subsystem.
The working memory model concerns active processing and appears to have wide practicalities into
areas such as verbal reasoning and understanding. The working memory model has practical
applications in supporting children's reading.
1. Baddeley (1975) used word-length effect tasks and blocking rehearsal information to
demonstrate that performance on word-length tasks depends on having access to an
articulatory system. If rehearsal is suppressed during commitment to memory (e.g. using a
counting back type task), then the word length had no effect. It is normally easier for us to
remember small words than long words and rehearsal plays an important part in this. If
rehearsal is suppressed, then word length is not important in memorising, thus this suggests
that there must be a system for processing this 'speaking to yourself' or articulation.
2. Gathercole and Baddeley (1990) in their research found that children with hearing problems
had impaired memory and had difficulties saying whether words rhymed, perhaps suggesting
that there is a phonological loop deficit being illustrated in their studies.
The main weakness of the model is in the lack of clarity of the Central Executive. At present there
appears to be a scarcity of research around the CE and the visuo-spatial store. There needs to be
clarification about the integration of the working memory and the long term memory.