PSY342H1 Chapter Notes - Chapter 6: Short-Term Memory, Long-Term Memory, Computer Data Storage

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Published on 2 Aug 2012
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Chapter 6- Working Memory
We need to keep some bits of information accessible in mind to perform cognitive
operations of them, mull them over and transform them. This short term mental storage
and manipulation operations are collectively called working memory
Working memory is similar to a blackboard that temporarily holds information and
allows us to alter it, but once we are done with the information it can be erased
Computer Metaphor
Working memory is analogous to computer’s RAM, but comparison with RAM leads
to two further predictions:
1. Any program can access RAM, therefore, no fixed mapping of a part and its
related processes
2. As there is more RAM, we can multi-task more
Implications of the Nature of Working Memory
Working memory capacity; the amount of information that can be held accessible.
People vary in their working memory capacity and this variation accounts for the
differences in intelligence, learning etc
From Primary Memory to Working Memory: A Brief History
William James: Primary Memory, Secondary Memory, and Consciousness
Primary memory is the initial repository in which information can be stored and made
available to conscious inspection, attention and introspection. In this way, information
is continually accessinlr
Secondary memory/long term storage memory is the store from which information
cannot be retrieved without initiating an active cognitive process
Early Studies: The Characteristics of Short-Term Memory
Miller suggested that people can only keep 7 items active in the short-term storage and
this limitation influences performance on a wide range of mental tasks. This concept
was supported by the tests of short-term memorization
The short term memory is perceived as highly flexible and subject to manipulation
Single items can be grouped together into higher level units of organization called
chunks; that expand the capacity of short term memory. Chunking is governed by by
concept of meaningfulness
Words are put into phrase-chunks which is why it is easier for us to remember verbal
Recent research suggests that number of items held in the memory may just be 3 +/- 1
because if participants are prevented from chunking/rehearsing, the storage capacity is
perceived as much smaller
Short term memory is defined in terms of its short duration and high level of
Brevity of Duration
The idea is that information would be held in the short-term memory for a very brief
period of time if the participants are not allowed to rehearse the information.
This idea has been supported by the results of Brown-Peterson task; where accuracy
declines by 50% in the first 6 seconds and to 0 after 18 seconds
Investigations are also being made about sensory memory; a form of storage that serve
to keep a perceptual representation of a stimulus for only a few 100 milliseconds after
the sensory input is gone
For short term memory, it has been observed that forgetting is not because of passive
decay over time but because of the idea of interference
Ready Accessibility
Sternberg’s experiment: Participants were showed a list of digits and then after showed
a digit and were asked to make the judgment about whether or not the digit was in the
memory list. 4 things were measured:
1. The time required to process the stimulus
2. The time required to access and compare the items
3. The time required to make the stimulus-response decision
4. The time required to execute the motor decision
It was noticed that for each additional item added in the memory list, response time
increases by an average of 40 milliseconds
This task also leads us to the conclusion that memory scanning proceeds sequentially;
one at a time. However, processing may be parallel
The Atkinson-Shiffrin Model: The Relationship of Short-Term and Long-Term
The Atkinson-Shiffrin Model: In this model, short-term memory serves as the
gateway by which information gains access to long-term memory. Short-term memory
provides a means of controlling and enhancing via rehearsal and coding strategies
which lets the information enter into long-term memory
This model had a lot of support and was called the modal model but is no longer held
that strongly because working memory captures the idea better where information is
held for manipulation
Argument against the Atkinson-Shiffrin Model is that it emphasized the role of
sequence; information first comes into the short term memory and then enters the long-
term memory but people with short-term memory impairment can hold information in
the long term memory very well.
There are multiple systems available for short-term storage that are co-ordinated by
central control system that balances the processing and storage
The Baddeley-Hitch Model: Working Memory
A system that consists of two short-term stores and a control system.
Three characteristics that differentiate this model from the Atkinson-Shiffrin Model:
1. It does not state that the function of short-term memory is to provide route for
the information to the long-term memory but the function is to enable the
activities of cognition e.g. co-ordination, integration and manipulation
2. Emphasizes the relationship of a central executive; a control system that
governs the deposition and removal of information from short-term memory.
Allows the short-term memory to function optimally
3. It proposed two distinct short-term memory buffers; phonological loop which
is for verbal information and visuospatial scratchpad which is visuospatial
information. The two memory stores are independent of each other as in if one
is being used, the other can be optimally used as well. They both interact with
central executive for functioning
Baddeley-Hitch model does not emphasize the duration of short-term memory or its
relation to long term memory. Rather, it emphasizes its flexibility and its importance in
the manipulation of information
Understanding the Working Memory Model
The Phonological Loop
The phonological loop involves two subcomponents:
1. Articulatory rehearsal: When visually presented verbal information is
encoded, it is transformed into a sound-based code or auditory-phonological
code, the active refreshment comes from articulatory rehearsal where we
voice the sounds internally – shadow the words without real understanding
2. Phonological store: Once the information is rehearsed in the mind, then it can
be heard again by the mind’s ear and maintained in the phonological store
Working memory depends on level of phonological processing i.e. translating verbal
information into sound-based code and articulatory processing i.e. translating verbal
information into speech-based code
If for some reason, phonological loop stops working, one can always use the
visuospatial scratchpad e.g. you cannot internally speak your ideas because you are
listening to someone else talk then you start to visually write your idea
Phonological similarity effect; when items simultaneously stored in working memory
have to be serially recalled then performance is worse for phonologically similar words.