LO: To describe the
main components in
the working memory
Baddeley and Hitch (1974)
Working Memory (STM) is…….
“that bit of memory you are USING when you
are WORKING on something.”
21 + 12 + 52 =
Work this out in your heads in silence...
• 17 + 29 + 30 = 76
• 43 + 12 + 23 = 78
• What process do you use to work
these out?
Baddeley & Hitch (1974)
• Believed memory is not just one store but a
number of different stores:
– 2 visual tasks = poorer performance but 1 visual and 1
verbal means no interruption
• Focused on STM ONLY and believed it was not a
unitary store (like MSM)!!
• LTM as a more passive store that holds previously
learned material for use by the STM when
• The Working Memory Model (Baddeley &
Hitch, 1974)
Central executive
• Key component in model
• Functions:
–Direct attention to tasks
– Determine how resources
(slave systems) are allocated.
• Limited Capacity
Phonological Loop
• Limited Capacity
• Deals with auditory information and
preserves word order
• Baddeley (1986) further subdivided it into
– Phonological store ( holds words heard)
– Articulatory process ( holds words heard/seen
and silently repeated ( looped) like an inner
Visuo-spatial sketch pad
• Visual and/or spatial information stored
– Visual = what things look like
– Spatial = relationships between things
• Limited capacity
• Logie (1995) suggested subdivision:
– Visuo-cache (store)
– Inner scribe for spatial relations.
Episodic Buffer
• Baddeley ( 2000) added episodic buffer as he
realised model needed a more general store.
• Slave systems deal with specific types of
• Central executive has no storage capacity
• Buffer extra storage system but with limited
• Integrates information from all other areas.
Evidence for the Working
Memory Model.
• To test the idea of more than one component,
Baddeley and Hitch devised the dual task
• Let’s see what happened…..
Your turn!
• You will now complete a dual task technique ( one that
was used by Baddeley and Hitch).
• Repeat the numbers below aloud whilst ticking the
true/false answers
B is followed by A
A is preceded by B
A is not followed by B
B follows A
B does not follow A
B is not followed by A
A follows B
B is not preceded by A
A is not followed by B
B does not precede A
Their research (Baddeley & Hitch)…..
• Asked participants to perform a reasoning task whilst
simultaneously reciting aloud a list of 6 digits.
• If digit span is really a measure of STM capacity,
participants would be expected to show impaired
performance on the reasoning task because their
STM would be fully occupied.
• However, found Participants made few errors on
either, though the speed was slightly slower.
1) What did they do in the experiment (HINT: it’s
what you did!!)
2) How does this support evidence for the
working memory model?
Evidence for the central executive
• Baddeley (1996) investigated selective attention and
switching retrieval plans. Asked participants to generate
random strings of digits on a keyboard (this is quite hard
as you have to pay close attention in order to avoid some
kind of pattern emerging).
• This was carried out alone or alongside another task such
as reciting the alphabet, counting from one or alternating
between letters and numbers (A1, B2, C3).
• The generated digit string became increasingly less
random in Condition 3 where participants had to switch
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.
More evidence for CE
• Individuals had to perform two tasks
simultaneously (dual task) rather than one after
the other (single task).
• Bunge et al (2000) used fMRI to see which parts of
the brain were most active when participants were
doing two tasks (reading a sentence and recalling
the final word in each sentence).
• The same brain areas (pre-frontal cortex) were
active in either dual or single task conditions but
there was significantly more activation in dual task
Evidence for the phonological loop
and articulatory process
• Remember the following:
• Harm
• Twice
• Calm
• Share
• Tree
• Book
• Sun
• Four
• Key
• Short
Recall them!
• How many did you get right?
• Harm
• Twice
• Calm
• Share
• Tree
• Book
• Sun
• Four
• Key
• Short
And again..recall these:
• Association
• Representative
• Discouragement
• Meaningfulness
• Suppression
• Enhancing
• Component
• Performances
• Forgetting
• Damaging
Recall them!
• How many did you get right?
• Association
• Representative
The phonological loop
• Discouragement
explains why the word• Meaningfulness
• Suppression
fact • that
people cope
• Component
than• long
words in working
• Forgetting
• Damaging
Word- length effect
• It seems that the phonological loop holds the
amount of information that you can say in 1.5
- 2 seconds (Baddeley et al, 1975).
• This makes it hard to remember a list of long
‘representative’ compared to shorter words
like ‘harm’ and ‘twice’ and therefore inhibits
rehearsal of longer words!
BUT…articulatory process
• Word length effect disappears if a person is given
an articulatory suppression task (‘the, the, the’
while reading the words).
• The repetitive task ties up the articulatory
process and means you can’t rehearse the
shorter words more quickly than the longer ones,
so the word length effect disappears.
• This provided evidence for……
Evidence for the visuo-spatial sketchpad
• Baddeley et al (1975) demonstrated the existence of the
visuo-spatial sketchpad.
• Participants were given a visual tracing task (they had to
track a moving light with a pointer). At the same time they
were given one of two other tasks; task 1 was to describe
all the angles on the letter F, task 2 was to perform a
verbal task. Task 1 was very difficult, but not task 2,
presumably because the second task involved two
different components (or slave systems).
• This is also evidence related to the effects of doing two
tasks using the same or different components. This was a
highly controlled laboratory experiment using a repeated
measures design to eliminate individual differences.
However, the task was rather artificial.
• Logie (1995) Visual cache stores information about visual form and
colour and the inner scribe processes spatial and movement
• Klauer and Zhao (2004) supported this idea by asking participants to
carry out one of two primary tasks, either a visual task or a spatial task.
At the same time as doing this task they were asked to do either a
spatial interference task, a visual interference task or no secondary task
(control condition). They found that performance of the spatial task was
much poorer for people who were simultaneously carrying out the
spatial distracter task than for people who were doing the visual
distracter task and vice versa.
• Studies using positron emission tomography (PET) scans have also
provided evidence for separate spatial and visual systems. There
appears to be more activity in the left half of the brain of people
carrying out visual working memory tasks but more in the right half of
the brain during spatial task.
Evidence for the episodic buffer
• Baddeley et al (1987)
– PPTs were shown words and then immediate recall
– Recall was much better for sentences (related
words) than unrelated
• Supports idea of ‘general’ memory store that
draws on LTM (semantics)
Evidence from brain damaged patients
• Case of KF (Shallice and Warrington, 1970)
showed that STM works independently of LTM
• STM forgetting of auditory information was
much greater than that of visual stimuli. Thus
his brain damage seemed to be restricted to
the phonological loop.
– Letters
– Meaningful sounds…ring ring
• SC - generally good learning abilities with the
exception of being unable to learn word pairs
that were presented out loud. This suggests
damage to the phonological loop (Trojano and
Grossi, 1995)
• LH - had been involved in a road accident.
Performed better on spatial tasks than those
involving visual imagery (Farah et al, 1988). This
suggests separate visual and spatial systems.