Transcript Cognitive Psychology

Cognitive Psychology
The working Model of Memory
By Baddeley and Hitch (1974)
Learning objectives
• Understand what is meant by the
concept of working memory.
• Describe the working memory model
and understand the functions and
limitations of its components.
• Describe and evaluate the evidence on
which the working model is based.
• Understand the strengths and
weaknesses of the model.
Background to the WMM
• Baddeley and Hitch (1974) believed that
there was more to STM than in the
multi-store model (i.e. more than just
being one store house).
The components of the WMM
• A complex and flexible system with different
components
A MORE ACTIVE MODEL OF MEMORY
3 main components
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The central executive (supervisor)
Has overall control
Limited capacity
Can process information from any
sensory modality
Central Executive
• Responsible for a range of control processes
e.g.
• setting task goals,
• monitoring and correcting errors,
• starting rehearsal process,
• switching attention between tasks,
• inhibiting irrelevant information
• Retrieving information from LTM
• Coordinating activity needed to carry out
more than one process at a time.
Two slave systems
• The slaves to the CE can be used as
storage systems
• Which frees up some of the CE’s
capacity to deal with more demanding
information processing tasks.
• The slave systems have separate
responsibilities and work independently
of one another.
1. Phonological Loop
• (the inner voice) has
limited capacity
• A temporary storage
system for verbal
information in a
speech-based form.
2. The visuo-spatial sketchpad
• The inner eye
• Limited capacity
• Temporary memory
system for holding
visual and /or spatial
information
Revised model (1999)
• Phonological loop now = passive storage
system called
• Phonological store which is linked to a
rehearsal system called
• The Articulatory Loop
• Maintained by subvocal repetition.
• The visuo-spatial sketchpad = passive visual
store called
• Visual cache (collection of data) which is
linked to an active ‘inner scribe’ that acts as a
rehearsal mechanism.
The dual task method
• To test the function of STM, Baddeley
and Hitch asked participants to
perform:
• A reasoning task (sentence-checking)
• While reciting a list of 6 digits.
• According to the multi-store model the
capacity of the STM would be taken up
with the digit task.
Recite the six digit number 482917 aloud while ticking True or False
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1. B is followed by A
2. A is preceded by B
3. A is not followed by B
4. B follows A
5. B does not follow A
6. B is not followed by A
7. A follows B
8. B is not preceded by A
9. A is not followed by B
10. B does not precede A
BA
AB
BA
AB
BA
AB
AB
AB
BA
AB
Findings
• Participants made very few errors on
either task (although the speed of
sentence checking was slightly slower
than when done on its own).
Conclusions
• Baddeley and Hitch concluded that STM
must have more than one component
and
• Must be involved in processes other
than simple storage, e.g. reasoning,
understanding and learning.
• STM is a kind of workspace where a
variety of operations can be carried out
on both old and new memories.
A MORE ACTIVE MODEL OF MEMORY
Very important
• Two tasks can be carried out at the
same time as long as
• They are being carried out by different
modalities (parts of the memory
system).
• LTM is a more passive store for
previously learned material.
• The ACTION is in the STM.
Evidence for the phonological loop
• Baddeley et al. (1975)
• Visual presentations of word lists for a brief
time
• Participants asked to write them down in
serial order.
• Condition 1 – lists consisted of 5 words
familiar, one-syllable English words, e.g.
harm, wit, twice.
• Condition 2 – 5 words, polysyllabic, e.g.
organisation, university, association.
findings
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More short words were recalled
This was called ‘the word length effect’
Conclusion
Capacity of the loop is determined by
the length of time it takes to say a
word rather than by the number of
items.
• The estimated time was 1.5 seconds
Method
• Laboratory experiment using a repeated
measures design
• Evaluation
• Well controlled
• Longer words may be less familiar than
short words. This could have affected
the recall rather than the length.
• No ethical issues if fully informed
consent obtained.
The word length effect under articulatory
suppression
• Participants were given a task that would
usually make use of the articulatory loop
• Asked to repeat a meaningless chant aloud
e.g. la-la-la
• The word length effect disappeared and recall
for short words was no better.
• This suggests that a verbal rehearsal system
is important and when suppressed,
processing has to take place elsewhere
(maybe the central executive)
Evidence for the visuo-spatial sketchpad
• The visual store also has limited
capacity.
• Shepard and Feng (1972) asked
participants to imagine folding flat
shapes in order to make a cube.
• They had to decide whether the arrows
would meet head on.
findings
• The time taken to make the decision
was related to the number of folds they
would have had to make if they had
actually been doing the task.
• Visual images work in a similar way to
real life perception.
• People are likely to find it difficult to do
two tasks simultaneously if they both
use the visuo-spatial sketchpad.
Research: Baddeley et al. 1973
Participants were given a tracking
task (following a spot of light with
a pointer around a circular path
while imagining block capitals such
as H, T, F and E.
• Participants were asked to start at the
bottom left-hand corner, to respond to
each angle with a ‘yes’ if it included the
bottom or top line of the letter and a
‘no’ if it did not.
FH
findings
• Participants had enormous difficulty in
tracking the spot of light and accurately
classifying the corners.
• The two tasks were competing for the
same limited resources of the visuospatial sketchpad.
• This is supported by the fact that
participants could carry out the tracking
task while performing a verbal task.
Logie (1995)
• Suggested that the visual cache stores
information about visual form and
colour
• The inner scribe processes spatial and
movement information.
Klauer and Zhao (2004) supported this
• Participants carried out one of two tasks:
A visual task
A spatial task
• At the same time they were asked to do
either
• A spatial interference task
• A visual interference task
• No secondary task (control condition)
findings
• Performance of the spatial task was
much poorer for those carrying out a
spatial distractor task at the same time
compared with those doing the visual
distractor task and vice versa.
• PET scans show evidence for separate
systems. Brain activity differs.
• More activity in the left half for visual
• More activity in the right half for spatial
Evidence for central executive
• Critical role in attention, planning and
coordination.
• Most flexible component of the working
memory.
• More difficult to find evidence for.
• Easier to study the slave systems.
• Research on the CE tends to focus on
the different functions.
Baddeley (1996)
• Investigated the functions of the CE in
selective attention and switching
retrieval plans.
• Participants were asked to generate
random strings of digits by pressing
numbered keys on a keyboard.
Try this (if you have a computer)
• Think of a sequence of eight digits that
show no systematic pattern (Note that
patterns easily emerge so this is
difficult).
• At the same time:
• Recite the alphabet
• Count from 1
• Alternate between letters and numbers
(A1B2C3D4E5F6 etc)
findings
• Baddeley found that the generated digit
string became considerably less random
in Condition 3 when particpants were
switching from alphabet to numbers at
the same time.
• Baddeley concluded that both the
random number generation task and
the alternation task were competing for
the same central executive resources.
Evaluation of the working memory model
• A very influential model
• Accepted by cognitive psychologists in
preference to the idea of a STM store.
• More plausible than the multi-store model
because it explains the STM in terms of active
process rather than passive storage alone.
• Verbal rehearsal is accepted as one optional
process within the articulatory loop rather
than the only way to transfer information to
the LTM.
More positives of the WMM
• It can account for some of the findings
that the MSM finds difficult to explain.
• Research support comes from dual-task
studies although
• KF could remember visual but not
verbal stimuli in STM – supports the
idea of at least 2 separate systems in
the STM.
• Brain scans show different areas of the brain
are used for visual and verbal tasks which
supports the WMM.
• The role of the CE is not fully understood and
it is likely to be comprised of more than one
component.
• Fails to account for musical memory as we
are able to listen to instrumental music
without impairing performance on other
acoustic tasks.