Models of memory
The Multi-store model
•Most well-known early model of memory processes
•Necessary first step
•Dominant model in no-scientific ideas about memory
•Central part of study of this process
• Atkinson and Shiffrin 1968
• Developed model to explain how memory is
organized
• Consists of 3 basic stores
– Sensory
– Short term
– Long term
Information must pass through all stages to get to the end
Sensory Store
• information received is sensory (visual, auditary, smell,
touch).
• Held in sensory stores for initial processing before
passing it on to STM (will decay if we don’t get to it)
• Info is either iconic or echoic
• Duration .5 (visual) – 4 seconds (echoic)
– Iconic storage = visual information
– echoic storage = auditory or sound information.
• Information from sensory memory is passed to short
term memory by attention i.e. taking notice of
something.
Sperling (1960)
Aim - To investigate the capacity of iconic memory.
Method - A three by four grid of numbers was flashed for
0.05 seconds. Followed by a high, medium or low
pitched tone to indicate which row was to be recalled.
Results - On average, the participants were able to recall
80% of the letters on the cued row.
Conclusions - Since the participants didn't know which
row was going to be called beforehand but still
managed to recall it well, you can assume that at one
time all of the information was held in the sensory
memory. But it decayed very rapidly.
Evaluation - Sensory memory stores are large but decay
very rapidly - lasting 250 to 500 milliseconds.
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Short Term Memory
Role:
• Holds on to info long enough to use it
Deals with :
– Incoming from sensory
– Retrieval of old info from LTM (part of schemata)
• Plays important role in conscious thought
• The cognitive work-space – manipulate ideas,
solve problems
Characteristics of STM
• Duration
– 15 – 30 seconds (Atkinson et. al.); 6 – 12 (Crane)
– Extend through rehearsal, repetition (inner speech)
• Capacity
– 7 items +/- 2 (Miller 1956)
– Can increase capacity through ‘chunking’ – grouping
information
– STM = ‘leaky bucket’
– The more items you put in, the more you displace
Coding
• Primarily acoustic
• Conrad (1964) – letters that sound similar
more likely to be confused than those that
sound different
• Can also be coded semantically
Long Term Memory (LTM)
• More permanent
• Use past experiences and knowledge for
future
• Bower (1975) – examples = spatial maps,
social norms
• Indefinite duration
• Unknown capacity
• Coding is primarily semantic and visual
Evaluation
Do separate stores exist?
• To justify the existence of three qualitatively
different types of memory store (sensory,
short-, and long-term), we must show major
differences between them.
– Temporal duration
– Storage capacity
– Forgetting mechanism(s)
– Effects of brain damage.
RECAP
• Activated information from long-term memory
is in short-term memory,
• Decay of that activation causes that
information to leave short-term memory, and
• Decay can be prevented by rehearsal.
Evidence supports separate sensory, shortterm, and long-term stores
BUT process oversimplified
Reality is more complex than unitary shortterm and long-term stores
– Warrington and Shallice (1972) showed that shortterm memory is not unitary. (based on a single
store)
– Shallice and Warrington (1974) showed that a
patient (KF) had variable problems with shortterm memory of different types of information.
– Logie (1999) discussed that short-term memory
often involves accessing the long-term store.
AND THE THEORY IGNORES:
• roles of proactive interference
• Roles of retrieval cues in short-term memory
and forgetting
EVIDENCE
• The theory states that forgetting is due to decay,
however proactive interference also has a role (Keppel
& Underwood, 1962).
• If forgetting is due to decay, forgetting should be rapid
in the absence of rehearsal.
– This was observed by Peterson and Peterson (1959) but
contradicted by Nairne et al. (1999; see E&K p. 194).
• Tehan and Humphreys (1996) present evidence against
the assumption that information in short-term memory
is directly accessible and depends on the nature of the
retrieval cue (see E&K p. 194).
THUS
Overall Evaluation
• Most assumptions in the standard model are
either incorrect or only partially correct.
Working Memory Model
• A model of STM
• Does not see the STM store as unitary
• BUT consisting of several components
(see notes)
http://generallythinking.com/blog/6-strengths-of-the-working-memory-model/
Exploration and activities
• http://www.psypress.co.uk/ek5/resources/de
mo_ch06-sc-02.asp
Strengths
• explains not only the storage, but also the
processing of information.
• Because the model proposes specific and
separate functions and subsystems, new
predictions and hypotheses can be drawn up
for testing (specificity)
• Consistent - with records of brain-damaged patients.
– Eg. the visuo-spatial sketch pad is said to be made of two
parts
• visual cache which stores information about colour and form
• inner scribe, which processes spatial and movement information.
– Patient ‘LH’ had more difficulty with visual tasks than
spatial tasks, which probably means that there is a
different part of the brain controlling these things; just as
the model suggests
– Another example is ‘KF’, whose forgetting of auditory
stimuli was higher than visual stimuli.
• Model integrates other research findings
– experimental evidence which supports the model
• Baddeley and his colleagues’ word-length effect supporting the
phonological loop
• a number of brain-scan studies have found different brain regions
to activate when people carry out tasks involving the different
components of working memory
Weaknesses
I: Components may as yet be too simple
• Model does not explain the full range of dayto-day phenomena
– Eg. some things we’re pretty good at
remembering, unless someone starts talking to us
while were trying to remember it.
– Is there any information that is NOT as prone to
decay as it is to interference from competing
input?
II: Central executive is poorly understood.
• There are only modest correlations between people on
different executive functions
• some people can lose some executive functions but
keep others
– SO - highly unlikely that the CE is one unitary construct.
• Do not know how CE is broken down so:
– difficult to come up with hypotheses to test the model
further
– Difficult to know how these subsections relate to each
other and the other parts of the model.
– Eg. Does the CE initiate verbal rehearsal, monitor it,
maintain it? Or is it purely a function of the phonological
loop?
III: Episodic buffer and how it works
• Researchers do not understand fully how the
episodic buffer combines information from
the other parts of the model, and from longterm memory.