Memory
The multi-store model of memory.
Specification topics covered: The multi-store model of memory: sensory, register, short-term memory and long-term memory.
Features of each store: coding, capacity and duration.
The specification
-The multi-store model of memory: sensory register, short-term and longterm memory.
-Types of long-term memory: episodic, semantic and procedural.
-The working memory model: central executive, phonological loop, visuospatial sketchpad and episodic buffer. Features of the model: coding and
capacity.
-Explanations for forgetting: proactive and retroactive interference and
retrieval failure due to absence of cues.
-Factors affecting the accuracy of eyewitness testimony: misleading
information, including leading questions, post-event discussion and anxiety.
-Improving the accuracy of eyewitness testimony, including the use of the
cognitive interview.
Making links with the specification…
-The multi-store model of memory: sensory
register, short-term and long-term memory.
All of our senses have a sensory
store, but for the MSM the sensory
store focuses on two main stores,
the iconic and echoic. The iconic
refers to visual imagery and the
echoic
refers
to
auditory
information. Iconic information is
encoded visually and echoic
information is encoded acoustically.
Information in the sensory register is
very brief, the duration is very
limited, less than half a second and
it has a very limited capacity.
For information to reach our
STM we must pay attention to
it. Information is held within the
store through maintenance
rehearsal and transfers to the
LTM by elaborative rehearsal.
The STM has a capacity of 7+/-2
and a duration of approximately
30 seconds.
Information is usually encoded
acoustically.
Information usually enters our
LTM from the STM via elaborative
rehearsal.
The duration and capacity for the
LTM is potentially unlimited.
Information is usually encoded
semantically.
Experiment
You will see a list of words, you will have thirty
seconds to remember the word list. You are
instructed to remember the words through your
use of memory, do not use any other means
(e.g. writing the words down). Words must be
recalled in the correct order.
Tap
Tan
Tar
Cap
Map
Bar
Rap
Ban
Ran
Lan
Car
Far
You have thirty seconds to write down
as many words as you can remember.
Hit
Lab
Tin
Pot
Pan
Lip
See
Now
Pop
Bow
Mum
Lap
You have thirty seconds to write down
as many words as you can remember.
Coding refers to the format in which information is stored in a memory store (e.g. acoustic).
Research on encoding
Evaluation
Baddeley and Baddeley (1966a, 1966b)
Participants were grouped into four different groups and given different lists of words
to remember. Participants were in the following groups
1) Acoustically similar words (e.g. cap, cat, can).
The stimuli used in Baddeley’s
research could be argued to be
artificial as the word lists have no
meaning to the participants.
2) Acoustically dissimilar words (e.g. pit, few, cow).
3) Semantically similar words (e.g. great, large, big).
Participants were asked to recall words in the correct order. When participants recalled
the words immediately their recall was less accurate for acoustically similar words. This
suggests that the STM codes information acoustically.
Also the task itself lacks mundane
realism, it is not often we are
required to participate in such
tasks. Therefore we must hold
caution when attempting to
generalise the findings to other
types of memory tasks.
When participants were required to recall information after a time period of 20
minutes (testing LTM recall) accuracy was lower for semantically similar words,
suggesting information is coded semantically in the LTM.
It has been found that people may
still use semantic coding for STM
tasks.
4)Semantically dissimilar words (e.g. good, huge, hot).
If participants struggle with a specific type of word on immediate recall, they may well
be confusing words for others or even recalling words which were not they. This
confusion suggests we code information in the specific way. Consider immediately
recalling cap, cat and can; there is a significant chance of recalling the word cab or cam
(or something similar). Consider recalling the following words great, large and big after
a twenty minute interval; there is a significant chance of recalling other semantically
related words such as huge or vast.
You need to write down the digits in
the correct order in which they are
presented.
XTYN
NBWDS
LDTNCS
ZPAKFRW
KSOEMALX
RMSKQPSAL
XIWKAMXALO
SOENVMALQDF
LDPQEMCNANGJ
Capacity refers to the amount of information which can be held in a memory store.
Research on capacity
Evaluation
Jacobs (1987) used the digit span technique to measure participants capacity in their STM.
Participants are given a sequence of digits and are required to recall these out loud in the
correct order. Each time the participant correctly recalls all digits it increases by 1 digit. The
maximum number of digits a participant is able to recall is their digit span. Jacobs found that
the mean span for items was 9.3 and letter 7.3
Jacob’s study has been challenged
on its validity as there was a
suggested lack of control. However,
further studies have confirmed
Jacob’s findings lending support to
its validity.
Miller (1956) suggests that the capacity for short term memory is 7 +/- 2 (roughly between 5-9
items). Miller suggests we can chunk information (organise it into a more meaningful
construct). For example consider the following two sequences of letters
Miller has been challenged on his
suggested capacity by Conway
(2001) who reviewed other
research and concluded the
capacity of memory was only four
chunks.
A R Y S C D W N J I Y L
B T E C G C S E G N V Q
The second sequence is easier to remember we can chunk the letters into three chunks
BTEC GCSE GNVQ
You will be presented with a trigram,
once the trigram has disappeared you
need to count aloud backwards in
threes from the number you see on
the screen.
VQL
297
Write down the trigram on your paper.
LQU
234
Write down the trigram on your paper.
IXV
252
Write down the trigram on your paper.
Duration refers to how long information can be held in a memory
store.
Evaluation
Peterson and Peterson (1959) measured duration by having participants remember a trigram (a
three letter nonsense word such as DVW) and a three digit number. Participants were asked to
count backwards from their three digit number in threes until told to stop. The reason for counting
back was to prevent rehearsal, when we engage our mind with another mental process it prevents
us actively rehearsing internally (which may improve duration). Participants completed 8 trials and
the total time they had to count backwards for varied and increased over each trial.
As is evident from the graph, after an 18 second interval almost all participants were unable to
recall the trigram, suggesting the duration of the STM is approximately 18 seconds.
Bahrick (1975) tested participants LTM
recall of former class members. This was
done in a number of ways which included a
photo recognition test and free recall test.
Participants tested 15 years after graduation
were 90% accurate in their photo
recognition and 60% accurate in their free
recall. Participants tested after 48 years
after graduation were 70% accurate in their
photo recognition and 30% in their free
recall. These findings suggest that the LTM
can be potentially unlimited.
The stimuli used in the study
by Peterson and Peterson
can be challenged on the
stimuli used. It is not a usual
task to perform in everyday
life, therefore we may
challenge
the
generalisability of their
findings
to
everyday
situations (thus challenging
the external validity of their
research).
The stimuli used in Bahrick’s
study was high in external
validity. The stimuli used
was personal to participants
and accurately measured
their LTM recollection of an
event personal to them.
However, due to the nature
of the study other factors
were not controlled which
may have affected findings,
such as when participants
last looked at their yearbook
folders etc.
All studies described so far which support
the MSM can effectively be used as
evaluation as long as they are shaped.
Jacobs (1887)
Miller (1956)
Baddeley and Baddeley (1966a, 1966b)
Peterson and Peterson (1959)
Bahrick (1975)
Do we really only have one STM?
Brain scans
The MSM suggest we have one STM,
however, a research study concerning KF
(Shallice and Warrington, 1970) suggests we
have we may have more than one STM
store. KF suffered amnesia, his memory for
digits was poor when they were read aloud
to him but memory improved when he was
able to read them himself. This suggests
there may be another STM for verbal
sounds.
Beardsley (1997) found the prefrontal
cortex was activated during STM but not
LTM tasks and Squire et al. (1992) found the
hippocampus activated during LTM.
Suggesting different stores use different
parts of the brain, thus supporting the
MSM’s claim we have separate stores.
The MSM is too simple
Type of processing and rehearsal.
All studies support one of more aspects of
the multi-store model of memory. You can
also use evaluations of studies in relation to
the MSM, again these must be shaped to
relate to the question you are answering,
More than one type of LTM?
We have different types of LTM (see types
of LTM Tulving, 1985) for example we learn
to walk and navigate, it has been suggested
this is a different type of LTM to factual
knowledge, something not explained by the
MSM.
Craik and Lockhart (1968) found that we are
likely to remember information more when
we process it semantically rather than
acoustically or structurally, they sagest for
us to remember something we need to
process it a specific way rather than simply
rehearsing it.
Craic and Watkins (1973) suggest that
rather than merely rehearsing information
(thus transferring it to our LTM) we need to
link it with existing knowledge, known as
elaborative rehearsal.
One big criticism is that the MSM is
considered too simple to give an effective
account of memory. As has been suggested
the STM and LTM are far more complex
than two simple unitary stores. Logie (1999)
suggests that the STM comes first in the
MSM but actually relies on the LTM to
process information This may be
commented on as an evaluation point in
your answer.