The Modal Model and Working Memory

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The Modal Model and Working Memory

• Lecture 2

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Evidence for the Stm/Ltm distinction

• Neurocognitive evidence
• HM (Milner) no transfer to ltm
• JB (Shallice and Warrington) impaired stm
  otherwise normal
• Brown/Peterson paradigm
• trigrams presented
• count backwards by 3s
• precipitous forgetting in 18 seconds
• Reitman
• part of forgetting due to similarity of items
• engaging tone detection task prevented rehearsal
  but did not impair recall
• suggests interference, not lack of rehearsal
  produces initial forgetting
• nevertheless, no transfer to ltm

3

• Car
• Hat
• Book
• Key
• Table
• Hand
• Bird
• Foot
• Lamp
• Tree
• House
• Flower
• Goat
• Paper
• Frog
• Rug
• Desk
• Shoe

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Evidence for STM/LTM serial position curve

• Dissociations
• logic some manipulations influence one section
  but not the other, suggests distinct sytems
• primacy affected by
• speed of presentation
• recency eliminated by
• delay
• interference

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Speed of presentation
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Delay
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Interference
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Atkinson and Shffrin explanation

• Transfer to ltm due to time in the limited
  buffer. As new information enters the buffer,
  items randomly eliminated.
• The longer in the buffer, the more likely for
  transfer to occur.
• Rundus rehearsal technique
• had people rehearse items out loud while hearing
  serial list
• frequency of rehearsal predicted everything but
  recency

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Problems with the modal model

• Not consistent
• if two distinct stores then properties should be
  more consistent
• variations in capacity depending on items
• forgetting characteristic vary depending on the
  stimuli
• Impaired STM does not hurt learning
• Possible to access LTM without going through STM
• pattern recognition
• Coding not always acoustic
• Rehearsal does not always lead to better memory
• Craik Watkins incidental learning task
• repeat words beginning with specific letter
• duration of repetition did not alter memory

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Depth of processing

• Repetition depends on the depth of processing
• Type 1 processing
• maintenance rehearsal
• mere repetition
• less well remembered
• Type 2 processing
• semantic processing
• elaborative rehearsal
• better remembered
• Evidence
• Craik and Watkins lack of benefit of maintenance
  rehearsal
• Craik and Tulving
• orienting task
• physical (repeating letters)
• auditory (rhyming)
• semantic (meaning)
• surprise memory recall test
• semantic performance superior

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Problems with depth of processing

• circular definition
• transfer appropriate processing
• Morris, Bransford Franks 1978
• encoded semantically or acoustically
• tested semantically or acoustically
• optimism if matched

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Working memory approach

• Does STM provide working space for manipulating
  information?
• Assumptions
• temporary storage is involved in information
  processing
• allows independent sources to interact
• common system operates across wide range of tasks
• Basic model
• systems
• central executive provides the basic area in
  which calculations are made
• articulatory loop
• slave system for audition
• visual spatial sketch pad
• slave system for vision

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Working memory model
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Evidence for Central executive

• Load (concurrent digits) modestly impairs
• learning (primacy but not recency)
• recall
• sentence verification
• categorization
• reasoning
• everything but recognition

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Evidence for the phonological store

• phonological similarity effects
• pgtvcd harder than rhxkwy
• unattended speech effects
• hear nine digits accompanied with
• silence
• spoken words
• nonsense
• recall impaired by distraction regardless of
  meaning
• word length effects
• long words less well remembered
• Welsh digit span study

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Evidence for the visual-s sketch pad

• Brooks
• Examined competition between
• response
• pointing, tapping spatial responses
• speaking verbal response
• Task
• Verbal- judged words in a sentence
• Visual- imagined block letter
• speaking faster than pointing for visual task
• pointing faster than speaking for verbal task

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Brooks results
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Brandimonte, Hitch Bishop (1992)

• Examined effects of verbal suppression on memory
  for visual forms
• encoded pictures with or without verbal
  suppression
• imagined pictures and subtracted visual component
• attempted to identify remaining component
• result imagery performance was superior
  following verbal suppression