The development of Baddeley's multiple component Working Memory model

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The development of Baddeley's multiple component
Working Memory model

• COGS 551 Human Memory
• 05. 03. 2007

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1. The Baddeley Hitch WM model (1974) 3
components of WM
Slave system for Visuo-spatial information
(colour, location, shape)
Central system allocating attentional resources
to the 2 slave systems - modality-independent
Slave system for acoustic-phonological
informations. Mechanisms rehearsal loop and
recoding

• Baddeley (2003830)

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1. The Baddeley Hitch WM model (1974) 3
components
In a nutshell In its earliest conception, WM was
conceived of having a tripartite structure The
a-modal central executive takes attentional
control over the memory process by allocating
memory resources to the two modality-specific
subsystems, the phonological loop (for
acoustic-verbal material) and the visuo-spatial
sketchpad (for visual and spatial material).

• Baddeley (2003830)

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Second version fractionating the VSSP and the
phonological loop

• Visual cache
• Passive short term storage of visual material

• Inner scribe
• Encoding and active rehearsal of spatial sequences

VSSP

• Inner speech/voice
• Encoding and active rehearsal of durable auditory
  images of words

• Inner ear/phon store
• Passive short term storage of acoustic image

Phon loop
Baddeley (1996)
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2nd fractionation
Visual
Cache
Inner
Scribe
The phonological slave system was
fractionated into a phonological store and Inner
speech
The visio-spatial slave system was
fractionated into a visual cache
(visual) and Inner scribe (spatial)
Inner
Speech
PERCEPTION
Psychology 4 OptionHuman Working Memory
Lecture 3Professor Robert Logie
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Third version The fractionation of the Central
Executive

• The simplifying assumption of CE as a unitary
  attentional system has been given up in favour of
  a multiple CE
• 3 Tasks
• Attentional control, i.e., focus, divide and
  switch attention
• Connect WM with LTM, e.g., for chunking (allowing
  information in LTM to supplement immediate serial
  recall)
• Allowing the slave systems to interact, in a
  separate WM component, distinguishable from LTM
  --gt The Episodic buffer

Baddeley 2000, 2003
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A fourth component in WMThe episodic buffer

• 'Limited capacity store that binds together
  information to form integrated episodes. It is
  assumed to be attentionally controlled by the
  executive and to be accessible to conscious
  awareness. Its multi-dimensional coding allows
  different systems to be integrated, and conscious
  awareness provides a convenient binding and
  retrieval process.' (Baddeley, 2003)

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The episodic buffer as a 4th component in the
multiple WM model
Baddeley, Alan D. (2003) 835
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The relation between WM, sensory processing, and
LTM

• The phonological loop, the VSSP, and the Episodic
  Buffer are
• NOT extensions of LTM but separable storage
  systems of WM
• NOT extensions of modality-specific processing of
  e.g., auditory and visual information
• Episodic memory forms an intermediate multi-modal
  store in the service of the Central Executive

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Functions of the Episodic Buffer

• Conscious awareness
• WM plays a role in consciousness
• --gt visual images, auditory-verbal imagery
• --gt phenomenological experience of remembering
• Problem where are the complex images stored?
• Binding
• How can information from various modalities be
  bound together into the representation of a
  coherent array of objects?
• --gt where and how does this binding take place?
• Problem solving
• By enabling the creation of new cognitive
  representations, the Episodic Buffer may
  facilitate problem solving

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Functions of the Episodic Buffer

• Chunking and prose recall
• The phonological loop can hold up to 7/-2
  elements, e.g., words, in working memory
• If aided by LTM, up to 16 units can be memorized
• --gt consciously chunked into a semantically
  coherent sentence, e.g., when instructed to
  combine these units to form a sentence
• --gt where and how is information from WM and LTM
  integrated?

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Evidence for the Episodic BufferAmnesic patients
with good immediate prose recall

• There were two amnesic patients who had
• Impaired LTM ('densely amnesic') but
• Normal immediate memory for passages of prose of
  about 25 chunks ('idea units')
• Normal capability of playing bridge
• How could they have 'intermediate' memory (longer
  than WM) but have no LTM?

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Functions of the Episodic Buffer

• Rehearsal
• In the phonological loop, subvocal rehearsal
  maintains phonological information
• Subvocal rehearsal is a direct output process
  equivalent to vocalization
• BUT children also have some kind of rehearsal
  before they have the adult strategy of subvocal
  rehearsal
• BUT What about rehearsal in other modalities
  without a direct output process, e.g., in the
  VSSP
• --gt There is a more general process of rehearsal
• It may involve sequential attention to the
  components to be remembered, either in the
  auditory or visual modality
• --gt Where does this general rehearsal take place?

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Biological implementation of the Episodic Buffer

• 'Binding' of information through synchronous
  firing of nerve cells in nerve cell assemblies
• No concrete anatomical location but involvement
  of the Prefrontal Cortex PFC (--gt Central
  Executive)
• Right frontal lobes involved in combining two
  separate tasks, verbal and visual (Prabhakaran et
  al. 2000)

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References

• Baddeley, Alan D. (1996) The fractionation of
  working memory. Proc. Natl. Acad. Sci USA, 93,
  13468-13472.
• Baddeley, Alan (2000) The episodic buffer a new
  component of working memory? Trends in Cognitive
  Sciences, 4, 417-432.
• Baddeley, Alan (2003) Working memory Looking
  back and looking forward. Nature Reviews
  Neuroscience, 4, 829-839.
• Baddeley, A.D., Hitch, G. (1974). Working
  memory. In G.H. Bower (Ed.), The psychology of
  learning and motivation Advances in research and
  theory (Vol. 8, pp. 47--89). New York Academic
  Press.
• Prabhakaran, V. Et al. (2000) Integration of
  diverse information in working memory within the
  frontal lobe. Nat. Neurosci. 3, 85-90.