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Working
Memory
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Chapter 5: Working
Memory
Episodic
Semantic
Forming and Using New
Memory Traces
Age
STM
LTM
Culture
Sensory
Memory
STM
Working
Memory
Retention
Echoic
Iconic
Storage
Retrieval
Format Capacity
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• Episodic vs. Semantic Memory
– Memory for episodic events vs. general knowledge
– Episodic: Storage, Retention, Retrieval
• Traditional View of Episodic Memory
– Two distinct memory systems
• Short-Term Memory: primary memory, short-term storage,
…
• Long-Term Memory: secondary memory, long-term
storage, …
• Evidence: e.g. Serial Position Effect (+1 +2)
– Iconic or Sensory Memory advocated by some
• Very transient storage of external stimuli
• Usually discussed in context of Perception
• Number of
rehearsals
correlated with
recall for
Primacy, not
Recency ( )
• Delay (filled to
prevent rehearsal)
results in loss of
Recency items,
not Primacy items
( )
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Educ
Executive
Functioning
Issues
Introduction
Applications
& Ind Diff
Introduction
Sternberg
Task
…
Neuroscience
Phonological Loop
Visuospatial Sketchpad
Central Executive
Buffer
Serial Position
Effect
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• Primacy Effect
– Better memory for
early items in list
– Rehearsal (+1)
– Long-Term Memory
• Recency Effect
Recency
Primacy
– Better memory for
later items in list
– Delay (+1)
– Short-Term Memory
Sensory Memory
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• Very transient memory for sensory events
– Veridical: i.e., exact replication of external stimulus
– Lost very quickly, or over-written
– May allow time for perceptual processes
– Specific to different sensory systems: Iconic, Echoic, …
Delay
• Iconic Memory
– Brief store of visual information in raw, uncoded form
– Move finger rapidly, sparkler (slide 1 +1), …
– Large capacity
– Fades in less than 1 second
– Varies with properties of stimulus (brightness) and
background (light vs. dark)
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Iconic Memory – Duration
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Visual Persistence & Iconic Memory
• Erikson & Collins
(1967)
• Segner (1740), Swedish
scientist
– Successive partial
displays
– Items in top two
panels shown
sequentially
– Meaningless alone but
superimposed images
reveal letters VOH
– Maximum interval at
which letters identified
– Inter-stimulus interval
(ISI) of 100-300 ms
– Glowing ember on
spinning wheel
– Increase speed until
complete circle seen
– Calculated time for full
revolution to estimate
duration of visual
sensory register
– Estimate = 100ms,
shorter than some other
procedures
Top
Display
Short
Interval
Middle
Display
Image Seen at Short Intervals
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Estimated
Duration of
Brief Visual
Stimulus
• Primary Iconic Memory task
• Early History
– Multiple letters shown briefly by Cattell (1885) and
others to measure Span of Apprehension: How
much information can people extract from single
glance?
– Baxt (1871): Subjects reported 4-5 letters from
single glance
– Similar claims about number of objects people can
perceive out of brief views of complex displays
– Cattell had concerns about such estimates
• Haber & Standing (1970)
– Estimate duration for flash to fade completely;
adjust click to coincide with stimulus on and off
– Subjects 1 & 2: Diagonal if Perceived = Actual
– 250 ms estimate for Sensory Register
Sperling Task
• Display shown briefly ( )
– 3, 4, 5, 6, 8, 9, 12, 16 letters
• Whole Report
– Participants report 4-5 items,
about 38% correct
– Subjectively, briefly “saw” more
but lost before reported
• Partial Report
– AFTER display off, Tone or other
signal randomly cues row to report
– 3 out of 4 or 75% correct for row,
therefore .75 X 12 = 9 items in
Iconic Memory (+1)
– Lost after short delay (+2)
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Sperling Task
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• Subjects said they “saw” more items than could report
• Items faded quickly
Partial and Whole Report
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• With immediate
cue (No Delay),
subjects
recalled almost
perfectly
• Partial Report
Score =
Proportion
Correct for Row
X Number of
Items in
Display (e.g., ¾
from cued row
X 12 items in
display = 9)
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• When cue for
row delayed
even 300 ms (.30
sec), recall lower
and closer to
whole report
value
• Sperling
concluded that
complete
information in
Sensory Register
but lost very
rapidly
• “Forgetting” also
due to Masking
effect (+1)
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Partial Report and Decay
Masking
Effect of
Circle
• Using circle to
indicate
location masks
(i.e., erases)
letter at that
location
• Subjects not
even aware
anything
presented in
cued position
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Echoic Memory
Short-Term
Memory
• Echoic Memory (Auditory)
Errors
– “Four-eared” partial report
technique, cued by light
– Echo lasts longer than
icon, perhaps 20 seconds
– Suffix effect: another
sound presented after
target “masks” echoic
memory
– May be cued by category
– Modality effect:
auditory > visual
– Similar sounding
letters: confuse
“G” & “P” more
than “R” & “P” ( )
– Also words: map,
man, mad vs cow,
day, few
– Same confusions
in STM and
listening tasks:
BCPTV vs.
FMNSX, r = .64
between errors
– Word length (
+1)
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– Longer than Sensory
Memory
– Free Recall: Recency
– Memory Span
– Probe-Digit Task (later)
– Brown-Peterson Task
• Present 3-Consonant
Trigram
• Tactual Memory
• Issues
STM Storage
Format
• Temporary memory
• STM Tasks
B K G
– Sensory Memory may
allow time for perception
– Attention: hearing “name”
– Some question usefulness
• Phonological Code
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• Participant counts
backward by 3’s
• Results ( )
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Word Length Effect: Memory Span
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• Reading Speed
– Memory span
greater for material
read more quickly
(-1)
Storage: Capacity of STM
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• Capacity
– Amount of information that can be stored in STM
– Depends on qualities of stimuli: e.g., word length
• Reading Speed
• Articulatory
Suppression ( )
– Capacity larger for items that can be read faster
– Word length, # Syllables, … slide 18
– Later slides on Culture (Language) & STM
– Repeat sound
– Disrupts STM
– Eliminates word
length effect
(Baddeley et al,
1975)
• Chunking
– Units can be integrated into Chunks: e.g., letters vs
words
– Miller: hypothesized 7 + 2 Chunks, BUT
– Training & Chunking (+1 +2 +3)
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Chunking: Binary Digits
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Memory Span and Chunking
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• Can encode binary digits (0, 1) into higher-order units: Octal
coding (or higher below) (results +1)
421
000=0
421
001=1
421
010=2
421
011=3
421
100=4
421
421
101=5 110=6
421
111=7
• E.g., 18 binary digits: 011 000 111 010 111 100
= 6 digits:
3 0 7 2 7 4
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• Ericsson (1980)
Chunking
& Practice
–
–
–
–
4 Subjects practiced digit span task
1 hr day, 3-5 days a week for 20 months (230 hrs)
Digit span increased from 7 to 80, especially for SF
NB: did not generalize to other stimuli
•
•
SF: cross-country
runner grouped
numbers into sets of 34 digits stored as
running times, track
races, ages, or
significant dates
(Yount, p. 76)
e.g., 3492 = 3 min
49.2 sec mile, near
record
STM: Retention & Forgetting
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• Retention duration: about
20 seconds
• What is forgetting due to?
• Decay
– Passage of time
• Interference
– By subsequent events
• Waugh & Norman
– Probe-Digit task (right)
– # interfering items critical,
rather than time
– Subtle effect of time?
END
OF LIST
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STM: Retrieval
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• How do we “find” items in STM?
Working Memory
• Baddeley
– Found that holding items
in STM interfered with
various cognitive tasks
– Appears automatic, but …
• Sternberg Scanning Task
•
•
•
•
– View memory set: 1-6 letters
– Probe letter: In memory set?
– RT for “yes” or “no” responses
• limited capacity temporary
storage that underpins
complex thought
– Parallel (A)
– Serial SelfTerminating
(B)
– Serial
Exhaustive (C)
– 4 Components (F5.5 )
– WM Span Tasks
– Visuospatial: e.g.,
memory for locations of
dots on screen
• Results ( )
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Executive
Functioning
• People with higher WM
capacity better able to
control cognitive focus!
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– Less susceptible to
inattentional blindness
– Less attention drawn to
misleading cues
• Stimulus Independent Thoughts (SITS)
• Thoughts or images unrelated to task: e.g., daydreaming,
rumination, …
• Anti-saccade task ( )
• Dichotic listening: hear own
name in unattended ear 20% vs
65%
– SITS & interfering tasks (Teasdale et al, 1995)
• Verbal: silly sentences task, “Bishops can be bought in
shops”
• Visual/Spatial: find hidden figures (above)
– Better at reasoning and
decision making
– Less misled by leading
questions in eyewitness task
– Stopped at times to ask their thoughts
• Fewer SITS in both cases
• Also fewer with less practiced tasks
• WM = STM + Attentional
Control
– Concluded that Executive implicated in SITS
Neuroscience of Memory
A is before B B A
Reading
Recall
…
– Proposed WM model
• Possible results
(F5.4 )
WM & SITS
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• Memory implicates numerous regions of brain
– Information not “stored” in specific location
– Diverse processes involved in memory & forgetting
• Case Study of H.M.
– Surgery removed most of hippocampus, amygdala,
other temporal lobe areas
– Could not transfer new memories to LTM (but see later
material on Implicit Memory)
– Could remember information from years before
operation
– Supports distinction between STM and LTM
PET Scan Studies
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• Baddeley WM model
– Verbal WM: left frontal and parietal lobes
– Spatial WM: right parietal, temporal, and frontal lobes
• Supports Baddeley’s view of separate components
of WM (below, +1)
• Hebbian Learning, Long-Term Potentiation
• Frontal Lobes
– Executive Functioning impaired: distractible, inhibition
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WM & Frontal Lobes
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Individual Differences & Applications
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• Childhood
Development
• Patients with early Schizophrenia (Sumiyoshi
et al, 2013)
– STM & WM develop
slowly during
childhood (F12.4 )
– & Metacognitive
Ability (Yussen &
Levy, 1975)
• Young children poor
judges of how much
they will remember on
STM tasks ( )
Report #s
in order
– Speech rate (+1)
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Childhood
Development,
Speech Rate,
and STM
- Slow,
Medium, and
Fast
Speakers at
each Age
(Hulme et al,
1984)
STM Retrieval (Sternberg task)
Age & Ability
(Keating &
Bobbitt, 1978)
• Effects of various individual
differences on STM Retrieval
(Hunt, 1978)
–
–
–
–
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Aging,
STM, and
Chunking
(Taub,
1974)
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Age: HS vs. Adult
Aging: Adult vs Elderly (+1)
Ability: Adult/HS vs. Low Ability
Adult vs. Mnemonist (parallel?)
Culture (Language) & STM
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• Word Length Effect Within & Between languages
• Languages differ in # syllables in words, numbers, … (below)
• STM and Reading Rate Across Languages (+1)
Language
Articulation Rate
Digit Span
Chinese
265 ms/digit
9.9
English
321 ms/digit
6.6
Welsh
385 ms/digit
5.8
(Hoosain & Salili, 1988; Ellis & Hennelly, 1980)
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#
0
1
2
3
4
5
6
7
8
9
English
Zero
One
Two
Three
Four
Five
Six
Seven
Eight
Nine
Arabic
Sifer
Wahid
Ithinin
Thalatha
Arba’a
Khamsa
Sita
Saba’a
Thamania
Tisa’a
Hebrew
Ef-es
AH-aht
Shtah-yeem
Shah-losh
Ar-bah
Hah-mesh
Sesh
Sheh-vah
Shmoh-neh
Tay-shah
Chinese
Ling
Yee
Uhr
Sahn
Suh
Woo
Lyo
Chee
Bah
Jo
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STM and Reading Rate across
Languages
STM & Education
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• Various ways in which STM relevant to Education
• Learning to read
– Poor readers: reduced memory spans, difficulty manipulating
phonological information (e.g., given Stop, reply Top)
• Language comprehension:
– STM patients, such as TB, have some difficulty comprehending
complex sentences e.g. “The boys pick the apples” OK, but “The
two boys pick the green apples from the tree” impaired
• General Cognitive Ability
– STM/WM tasks appear on Ability tests
– STM/WM correlates with IQ, which correlates with academic
success, employment success, and other factors
– Ackerman et al (2005): meta-analysis, 86 studies, average r = .48
between WM and IQ; higher for aggregate measures (+1)
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– STM and “creativity”: generation of animal names (+2)
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Reanalysis of
Ackerman et
al by
Oberauer et
al. (r = .85)
General
Intelligence
Articulatory Suppression
reduced difference
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STM / WM &
Success
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• Education ( )
STM / WM &
Clinical
Psychology
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• Job Performance
– High STM / WM
demand jobs: e.g., AirTraffic Controller
– Correlation with job
performance (Verive &
McDaniel, 1996)
• Meta-analysis of 11
studies, 34,262 subjects
• STM predicted
performance in job (r =
.41) and training (r = .49)
• STM tests showed
smaller racial mean
differences than test of
general cognitive ability
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• STM/WM deficits have 42
been observed in diverse
disorders:
– PTSD
– Schizophrenia (Kopelowicz
et al, 2005)
– ADHD (Martinussen, 2005)
– Anxiety (Neubauer, 1999):
fail to exclude irrelevant
information
• Deficits in Schizophrenia
improve on remission
(Kopelowicz et al, 2005)
• Good STM capacity may
provide buffer against
other risk factors for
alcohol abuse (Finn &
Hall, 2004) ( )
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Review
• Memory active process
involving encoding,
storage, and retrieval
• Modal approach divides
memory into Sensory
Memory, Short-Term
Memory, and Long-Term
Memory
• STM holds about 7
pieces of information for
about 20 seconds
without rehearsal
• Code in STM appears to
be acoustic
• Searching STM is serial,
exhaustive process
• New conception of STM
is “Working Memory,”
emphasizing its active
nature
–
–
–
–
Visuospatial sketchpad
Phonological loop
Episodic buffer
Central executive
• Brain structures such as
hippocampus play role in
memory formation
• Many applications of WM
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