The Working Memory Model

LO: To describe the main components in the working memory model.

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 =

• 43 + 12 + 23 =

• What process do you use to work these out?

76

78

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 needed.

• 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 voice.

Visuo-spatial sketch pad• Visual and/or spatial information stored

here– 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

information.

• Central executive has no storage capacity

• Buffer extra storage system but with limited

capacity.

• 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 technique.

• 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

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• 1: B is followed by A BA True/False• 2: A is preceded by B AB True/False• 3: A is not followed by B BA

True/False• 4: B follows A AB True/False• 5: B does not follow A BA True/False• 6: B is not followed by A AB

True/False• 7: A follows B AB True/False• 8: B is not preceded by A AB

True/False• 9: A is not followed by B BA

True/False• 10: B does not precede A AB

True/False

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.

Summarise

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 condition

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• Discouragement• Meaningfulness• Suppression• Enhancing• Component• Performances• Forgetting• Damaging

The phonological loop explains why the word- length effect occurs – the fact that people cope better with short words than long words in working memory (STM).

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 words such as ‘association’ and ‘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.

Also….• Logie (1995) Visual cache stores information about visual form and

colour and the inner scribe processes spatial and movement information.

• 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

Also….• 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.