Lecture 4 Psyco 350, A1 Fall, 2006

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Lecture 4 Psyco 350, A1Fall, 2006

• N. R. Brown

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Outline

• Properties of STM
• Capacity Span Task
• Duration/Forgetting Brown-Peterson Task
• Retrieval Sternberg Task
• Problems w/ Modal Model
• Dual Task Experiment
• Baddeleys Model of Working Memory

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Sternberg Task Results

• RT ? w/ set size
• Implication serial
• Negative Positive
• Implication exhaustive
• Sternbergs conclusion
• process serial exhaustive

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Sternbergs Model
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Problems / Serial Exhaustive Process

• Conceptual
• 40 ms/comparison seems awfully fast.
• Empirical
• Repetition Effect (Baddeley Ecob, 1973)
• Probe T RTWTN lt RTWGN
• Serial Position Effects (Corballis et al., 1972)
• Probe T TRWGN lt RTWGN

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Alternative Approach to Sternberg Findings

• Assumptions
• memory set, the most active portion of LTM
• memory searched in parallel
• decision process
• Yes probe-memory similarity gt threshold
• No at deadline similarity lt threshold
• Set Size Effects
• encoding activation/item ? as set size ?
• retrieval speed of assessment ? as set size ?

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STM, But

• Model Modal accounts for serial position curve,
  but
• not long-term recency effects.
• Capacity of STM is limited, but
• also affected by chunking expertise.
• In the absence of rehearsal, information is
  forgotten rapidly, but
• not on the first trial.
• Serial exhaustive process may be used to scan
  STM, or
• a parallel process may be used to assess the
  active contents of LTM.
• Simple slot model cant account for performance
  of classic STM task.

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Dual-task Performance the Demise of STM

• STM In Modal Model
• single component short-term store
• functions
• temporary storage lists, task relevant info
• transfer to LTM via rehearsal
• A single system for holding and manipulating
  information for a wide variety of tasks such as
  learning, comprehension, and reasoning
• -- Baddeley, p. 67

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Dual-task Performance the Demise of STM

• A Dual Task.
• encode list of digits
• perform a cognitive task (e.g., reasoning,
  comprehension)
• recall list of digits.
• If both load and task make use of same store,
  then increasing load (to span) should disrupt
  performance on cog task.

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Grammatical Reason W/ Memory Load (Baddeley,
1986)

• Concurrent Tasks
• Memory span task provides a memory load
• Grammatical reasoning task
• Procedure
• auditor presentation of digit load 1 digit/s
• concurrent overt rehearsal of load
• visual presentation of letter pair sentence
• respond T/F to sentence
• serial recall of digits

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Grammatical Reasoning Task

• Design
• memory load
• 0 to 8 digits
• sentence type
• true value X voice X affirmation

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Implications of Single-store View

• Assumptions
• Span Task absorbs (almost) all STM capacity
• Reasoning task requires access to STM
• Prediction
• If span task absorbs all of STM ?
• dual task requirements should produce a dramatic
  impairment in performance.
• Span-length memory load ? catastrophic
  interference

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Dual Task Reasoning Results

• No effect on reasoning when load is light (0-2)
• reason slowed by load
• error rate low regardless of load.
• -----------------------------------
• Load also has negative, but non-catastrophic,
  impact on free recall text comprehension

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Implication of Dual Task Performance

• System responsible for digit span cannot be the
  same as system responsible for learning /
  reasoning.
• Motivated the development of the multi-component
  WM model.

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Working Memory An Alterative to STM

• Baddeley and Hitchs (1983) model
• Central executive
• Control center of working memory
• Two slave systems
• Phonological loop
• Processes verbal/acoustic information
• Visuo-spatial sketch pad
• Processes visual and spatial information

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Basic WM Model
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(No Transcript)
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Current WM Model
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Dual Task Reasoning Results

• No effect on reasoning when load is light (0-2)
• reason slowed by load
• error rate low regardless of load.

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WM Interpretation of Dual Task

• Load maintenance requires
• access to phonological store
• minor attentional resources to schedule rehearsal
• Grammatical reasoning requires
• attentional resources for sentence
  understanding/reasoning
• limited access to phonological store note
  sentences presented visually
• As load ?, attentional demands ?. Thus, less
  capacity available for sentence processing.

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Phonological loop

• Two components
• Phonological short-term store
• Phonological information that decays with time
• Inner ear
• Subvocal rehearsal process
• Articulatory-like rehearsal that needs active
  maintenance
• Inner voice

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The Phonological Loop
Articulatory Control Process Based on inner
speech
Auditory Presentation
Visual Presentation
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Phonological Loop

• Speech-based System
• phonological similarity ?
• irrelevant speech ?
• articulartory suppression ?
• 2-s Capacity
• word length effect
• cross-linguistic ?s
• developmental ?s

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Evidence for the Phonological Loop

• Instructions
• You will see 6 letters, 1/s.
• Recall them in order, at the signal.

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List 1
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(No Transcript)
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P
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G
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T
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V
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C
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D
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(No Transcript)
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Recall Letters
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List 2
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(No Transcript)
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R
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H
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X
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K
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W
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Y
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(No Transcript)
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Recall Letters
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Evidence for Phonological Loop

• Phonological Similarity Effect
• similar sounding list lt dissimilar sounding lists
• PGTVCD vs RHXKWY
• (Almost) No Evidence for Semantic Similarity
  Effect
• Implies representation is speech-based not
  meaning based.

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Evidence for Phonological Loop

• Irrelevant Speech Effect
• Recall impaired if items are accompanied by other
  verbal material.
• Effect found w/ same-language words,
  same-language non-words, foreign words.
• Interpretation
• unattended (linguistic) material was gaining
  access to the phonological store.
• -- Baddeley, p. 53

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Evidence for Phonological Loop

• Articulartory Suppression
• concurrent (overt or covert) articulation,
  decreases word span.
• (the, the, the one, two, three, one,
  two..)
• concurrent articulation decreases
• the phonological similarity effect
• word length effect.
• Interpretation
• articulation of irrelevant items dominates ACP -
  Words cannot be rehearsed or recoded into
  phonological code

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Evidence for the Phonological Loop

• Instructions
• You will see 5 words, 1/s.
• Recall them in order, at the signal

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List 1
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(No Transcript)
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golf
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bronze
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beast
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inn
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dirt
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(No Transcript)
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Recall Words
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List 2
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(No Transcript)
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gallery
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amplifier
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property
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mosquito
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officer
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(No Transcript)
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Recall Words
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Word Length Effect

• List 1
• golf
• bronze
• beast
• inn
• dirt

• List 2
• gallery
• amplifier
• property
• mosquito
• officer

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Evidence for Phonological Loop

• Word Length Effect
• word span decrease as of syllables/word
  increases.
• Recall depends of reading rate.
• words recalled 2 (reading rate)
• reading rate words read / s

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Phonological Loop Capacity of Phono Store

• Baddeley et al (1975)
• Task serial recall
• Materials5-word lists
• Manipulation syllable length
• Results
• recall ?, as syllable length ?
• recall predicted by reading rate.
• cf. STM predictions

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Phonological Loop Capacity of Phono Store

• Baddeley et at (1975)
• linear relation between reading time recall
• Interpretation
• capacity of phono loop
• 2 s of speech materials
• Reason
• fast fading phono trace
• rehearsal refreshes trace.
• if not rehersed within 2 s, most info lost.

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Phonological Loop Capacity of Phono Store

• Baddeley et at (1975)
• Implications
• across languages, digit span should be related to
  mean syllable length of digits.
• digit span should increase w/ age, because speech
  rate does.

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Cross-Linguistic ?s in Digit SpanNaveh-Benjamin
Ayers (1986)

• As predicted
• span larger for languages w/ short digits than
  long
• span 2 X reading rate

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Age-related ?s Digit SpanHulme (1984)

• As predicted
• span ? w/ age
• span 2 X speech rate
• -----------------------
• Overt or covert articulation serves to maintain
  items in the phonological store by refreshing
  their fading traces. The faster it can run, the
  longer the memory span

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Phonological Loops Functions

• Learning to read
• Children with impaired reading ability have
  reduced memory spans and have difficulties in
  tasks which require the manipulation of
  phonological information (e.g. given Stop, reply
  Top).
• Language comprehension
• STM patients some difficulty in comprehending
  verbose or complex sentences e.g.
• The boys pick the apples OK
• The two boys pick the green apples from the
  tree Impaired
• Vocabulary acquisition
• There is a strong correlation between non-word
  repetition (which strongly taxes the phonological
  loop) and vocabulary size (Gathercole Baddeley,
  1989)