Transcript Lecture_05

Lecture 5 – Psyco 350, B1
Winter, 2011
N. R. Brown
Psyco 350 Lec #5 – Slide 1
Outline
• Baddeley’s Model of Working Memory
–
–
–
–
Phonological Loop
Visuo-spatial sketchpad
Central Executive
Problems w/ WM
• An Alternative Perspectives on WM
– Reading& Operation Span tasks
– Cowan’s Embedded Processes Mode
– WM Capacity as Executive Control
Psyco 350 Lec #5 – Slide 2
The Phonological Loop
Phonological Store: holds small amount of speech based
information
Articulatory Control Process: Based
on inner speech
Phonological
Store
Visual
Presentation
Psyco 350 Lec #5 – Slide 3
Auditory
Presentation
Phonological Loop
• Speech-based System:
– phonological similarity 
– irrelevant speech

– articulartory suppression 
• 2-s Capacity:
– word length effect
– cross-linguistic Δ’s
– developmental Δ’s
Psyco 350 Lec #5– Slide 4
Evidence for the Phonological Loop
Instructions:
• You will see 6 letters, 1/s.
• Recall them in order, at the signal.
Psyco 350 Lec #5 – Slide 5
Evidence for Phonological Loop
• Phonological Similarity Effect
similar sounding list < dissimilar sounding lists
_______ vs _______
• Implies: representation is speech-based not
meaning based.
Psyco 350 Lec #4 – Slide 6
Evidence for Phonological Loop
• Irrelevant Speech Effect
– Recall impaired if items are accompanied by other
verbal material.
– Effect found w/: same-language words, samelanguage non-words, foreign words.
• Interpretation:
“unattended (linguistic) material was gaining access to
the phonological store.”
-- Baddeley, p. 53
Psyco 350 Lec #4 – Slide 7
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
Psyco 350 Lec #5 – Slide 8
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
Psyco 350 Lec #4 – Slide 9
Phonological Loop – Capacity of Phono Store
Baddeley et al (1975)
Task: serial recall
Materials:5-word lists
Manipulation: syllable
length
Results:
• recall , as syllable
length 
• recall predicted by
reading rate.
• cf. STM predictions
Psyco 350 Lec #4 – Slide 10
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 rehearsed within 2
s, most info lost.
Psyco 350 Lec #4 – Slide 11
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.
Psyco 350 Lec #4 – Slide 12
Cross-Linguistic Δs in Digit Span
Naveh-Benjamin & Ayers (1986)
As predicted:
• span larger
for languages
w/ short digits
than long
• span ≈ 2 X
reading rate
Psyco 350 Lec #4 – Slide 13
Age-related Δs Digit Span
Hulme (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
Psyco 350 Lec #4 – Slide 14
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)
Psyco 350 Lec #4 – Slide 15
Psyco 350 Lec #4 – Slide 16
VSSP
• Function:
– “construction, maintained, & manipulation of
mental images.”
– Radvansky, p. 97
• Assumptions:
– Independence of VSSP & Phonological Loop
Psyco 350 Lec #4 – Slide 17
Independence of VSSP & Phonological Loop
Brooks (1968)
• Dual Task Experiment
– Goal to demonstrate:
• spatial response mode interference w/ spatial
processing
• verbal response mode interferes w/ verbal
processing
• cross-modal tasks produce little interference
Psyco 350 Lec #4 – Slide 18
Independence of VSSP & Phonological Loop
Brooks (1968)
• Design (2X3)
TASK
X
image scanning
grammatical decision
Psyco 350 Lec #4 – Slide 19
RESPONSE MODE
pointing
tapping
vocal
Brooks (1968): Image Scanning Task
Given a block letter & starting point:
If current corner is top or bottom “yes”
Otherwise
”no”
Psyco 350 Lec #4 – Slide 20
Brooks (1968): Response Modes
While performing target task:
• Vocal – say “yes”/”no”
• Taping – left tap = “yes”; right tap = “no”
• Pointing – point to successive “y”/”n” pairs on
response sheet
Psyco 350 Lec #4 – Slide 21
Brooks (1968): Pointing
Psyco 350 Lec #4 – Slide 22
Brooks (1968): Results
>>
≈
• Spatial response mode:
– interfered w/ spatial task
– did not interfere w/ verbal task
• Verbal response mode:
– interfered w/ verbal task
– did not interfere w/ spatial task
Psyco 350 Lec #4 – Slide 23
≈
<<
Brooks (1968): Interpretation
• Task X Mode interaction indicates:
– separate & limited pool of resources for verbal
& spatial task
• image scanning task & spatial response mode
draw on the limited resources of the VSSP.
• grammatical decision task & vocal response
mode both draw on the resources of the
phonological loop.
Psyco 350 Lec #4 – Slide 24
Visuo-spatial sketchpad
Operations:
• Mental rotation
• Mental scanning
• Boundary extension
• Dynamic memory
Supports:
Spatial problem-solving (moving a couch
Prediction of dynamic consequences.
Psyco 350 Lec #5 – Slide 25
Mental Rotation: VSSP @ Work
Shepard & Metzler (1971)
Materials: Pairs of 3-d(ish) objects in a variety of
orientations.
Task: timed same/different judgment
Psyco 350 Lec #5 – Slide 26
Mental Rotation: VSSP @ Work
Shepard & Metzler (1971)
Materials: Pairs of 3-d(ish) objects in a variety of
orientations.
Task: timed same/different judgment
Psyco 350 Lec #5 – Slide 27
Mental Rotation
• Results:
– RT  w/ angular
disparity
• Interpretation:
“mental rotation has
characteristics that
mimic physical
rotation….It is almost
as if people are
actually mentally
turning the object
about in their VSSP.”
– Radvansky, p. 99
Psyco 350 Lec #5 – Slide 28
Problems w/ Baddeley’s WM
Influence of LTM on STM tasks
• chunking
• proactive interference (Keppel & Underwood, 1962) &
release from proactive interference (Wickens, 1972).
• semantic similarity can  span
• span: high frequency words > low frequency words
Problems with Phonological Loop
• under suppression: span > 0 for visually presented
words.
Psyco 350 Lec #5 – Slide 29
Current WM Model
Psyco 350 Lec #5 – Slide 30
Episodic Buffer
• Information is bound together in the
episodic buffer
– This creates the episodic memory trace
– Working memory interacts with long-term
memory
Central Executive (Baddeley)
• Most complex and least understood component
of WM
• Coordinates activity of slave systems &
supplements their attentional resources
• Other potential roles:
– coordinating retrieval strategies
– temporary activation of LTM,
– selective attention
– suppression of habitual responses.
Psyco 350 Lec #5 – Slide 32
Alternatives Perspectives On WM
Motivated by:
• Problems w/ Baddeley’s Model
• A need to better understand executive
functioning
• Predictive power of span task.
Three Related Issue
1. Reading/Operation Span as a measure of
“capacity”
2. WM contents as the active portion of LTM
3. WM as executive attention
Psyco 350 Lec #5 – Slide 33
Measuring WM Capacity
• Key Idea: Performance on complex cognitive task
reflects a number of different capacities
–
–
–
–
retrieval efficiency
processing efficiency
“attention-free” capacity of relevant slave system
attentional management (ability to focus on relevant
info & inhibit irrelevant info.
– etc.
• WM span tasks developed to measure relation
between WM and performance on complex cognitive
tasks
Psyco 350 Lec #5 – Slide 34
WM Memory Span
• WM span = # of words recalled
• Demonstrates capacity for holding load while
processing.
• Large individual differences in WM span (2-6
items)
• WM span measures predict performance on IQ,
achievement tests (e.g., SATs), & g.
• digit/word span uncorrelated with IQ/SAT tests
Psyco 350 Lec #5 – Slide 35
WM Memory Span – Two Interpretations
1. Domain Specific Capacity: Efficient
processing of immediate task, leaves
additional resources for maintaining load.
– Accounts for dual task performance (e.g.
Brooks)
2. Domain General Capacity: General ability to
“control attention to maintain information in
an active quickly retrievable state.” Engle,
2009, p. 20.
Psyco 350 Lec #5 – Slide 36
An Alternative: WM as Information
in an Active State
Psyco 350 Lec #5 – Slide 37
WM as Activation:
Cowan’s Embedded Processes Model
• Central Executive:
directs and controls
voluntary processing.
• Encoding:
– Incoming info activities
representation in LTM
Psyco 350 Lec #5 – Slide 38
WM as Activation:
Cowan’s Embedded Processes Model
Central Notation:
LTM in one of 3 states:
1. Dormant
2. Activated
– fades (decays) unless
reactivated
3. “In focus” (of attention)
– limited to 4 items
Psyco 350 Lec #5 – Slide 39
Span from Active Perspective
Two components:
1. read-out from focus
2. activated material, retrieved before decay
Predictions:
•
factors  LTM,  span
–
–
•
concreteness (Walker & Hulme, 1999)
word frequency (Roodenrys & Quinlan, 2000)
Span > 0 when rehearsal suppressed
Psyco 350 Lec #5 – Slide 40