1 ISE 412 Memory LONG-TERM MEMORY WORKING MEMORY SENSORY STORE.
Working Memory II Working memory, executive control, and prefrontal cortex Cognitive Science, 9.012...
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Transcript of Working Memory II Working memory, executive control, and prefrontal cortex Cognitive Science, 9.012...
Working Memory IIWorking memory, executive control,
and prefrontal cortex
Cognitive Science, 9.012
Nuo Li
4/27/06
What is working memory?
Active maintenance of goal related information in the face of distractors and interference. It’s task dependent and involves some degree of cognitive control.
What is working memory?
Some defining characteristics:
- goes on in consciousness- accessible to explicit form of expression
(declarative memory)- elaboration of short-term memory- selective- involves cognitive processing (e.g. recognition)
Atkinson & Shiffrin (1971)
• Parallel processing of inputs• Information are selected for entry into STM• STM = Working Memory = Control processes
– Selection– Rehearsal– Coding– Decision making
Baddeley & Hitch (1974)
WM = Executive Control + Domain Specific Modules
Outline
• Working memory (WM) and short-term memory (STM)
• WM, controlled attention, and fluid intelligence
• Role of pre-frontal cortex (PFC)
• Mapping from functions to structures
• Representation
Outline
• Working memory (WM) and short-term memory (STM)- WM Tasks- STM Tasks- Distinctions between WM and STM
• WM, controlled attention, and fluid integellence
• Role of pre-frontal cortex (PFC)
• Mapping from functions to structures
• Representation
WM tasks
Reading span (Daneman & Capenter, 1980)
Subject read (or listen to) a list of 2 to 6 sentences. Afterward, the subject recalled the last word of each sentence.
Demo
For many years, my family and friend have been working on the farm. SPOTBecause the room was stuffy. Bob went outside for some fresh air. TRIALWe were 50 miles out at sea before we lost sight of the land. BANDANSWER: SPOT, TRIAL, BAND
WM tasks
Reading span (Daneman & Capenter, 1980)
Subject read (or listen to) a list of 2 to 6 sentences. Afterward, the subject recalled the last word of each sentence.
Operation span (Turner & Engle 1989)
Subject solved a string of arithmetic operations and then read aloud a word that followed the string. After a series of such operation-word strings, the subject recalled the word.
Demo
Is (8/4)-1=1? BearIs (6 x 2)-2 =10? DadIs (10 x 2)-6=12? Beans
Answer: Bear, Dad, Beans
WM tasks (Memory span tasks)
Reading span (Daneman & Capenter, 1980)
Subject read (or listen to) a list of 2 to 6 sentences. Afterward, the subject recalled the last word of each sentence.
Operation span (Turner & Engle 1989)
Subject solved a string of arithmetic operations and then read aloud a word that followed the string. After a series of such operation-word strings, the subject recalled the word.
Counting span (Case, Kurland, & Goldberg 1982)
Subject is presented with up to eight displays. Each display consists of different number of targets, and two other kinds of distracters, all randomly placed. Subject is required to count the targets aloud, and report the final tally. After the series of displays, the subject is required to report previous final tally in order
Demo
Answer: 5 8 6 3 9 9
WM tasks
These tasks are thought to reflect some fundamental aspect of cognition. Score on these tasks predict a range of cognitive functions:
- Reading & listening comprehension- Following directions- Vocabulary learning- Note taking- Writing - Reasoning- Bridge playing- Computer language learning- etc
STM Tasks
Wechsler Digit Span Task
Forward SpanThe examiner verbally present digits at a rate of one per second. Subject is asked to repeat the digits. The number of digits increases by one until the participant consecutively fails two trials of the same digit span length.
Backward SpanThe backward test requires the participant to repeat the digits in reverse order.
WM & STM
What’s the difference?
WM & STM
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Keppel and Underwood (1962) found that forgetting in the Brown–Peterson distractor task depends on where in the experimental session performance is assessed. (On the very first trial, the recall performance was near perfect).
Brown–Peterson distractor task:
Recall trigram of consonants (e.g. GKT, WCH,…) after performing a number of algebraic computations (e.g., counting backwards by 3’s).
Goes against the classic notion of information has to be rehearsed in order to be retained.
Proactive interference plays an important role in short-term retention
Effect of Proactive InterferenceOthers also found similar effects:
Rosen & Engle (1998)Subjects (with high and low WM score) learn to associate 12 cue word with 3 list of other 12 words. Instruction emphasized accuracy
Example: list 1: bird-bath; list 2: bird-dawn; list 3: bird-bath; (re-learn)
Measured both timing and accuracy.
Result:List 1: sameList 2: low WM made more error (showed intrusion from list 1)List 3: high WM responded slower than low WM subjects, even slower than themselves on trial 1.
Conclusion: information in list1 is suppressed better for the high WM subjects, which affected their performance on later trials.
Effect of Proactive Interference
Kane & Engle (2000)Subject (with high and low WM score) had 3 trial in which they saw 10 words to recall. The subject performed a rehearsal preventative task for 16s.
Result:Trial 1: high WM and low WM subject performed the same (60%)Subsequence trials: low WM had steeper decline in recall performance
Adding secondary preventative task (adding interference load)
The two group performed the same.
Conclusion: When add more interference load, high WM subjects were hurt more, suggest that under normal condition, high WM subjects allocate more attentional control to combat the interference.
WM & STM
STMStorage of information.
Limitation: How many item can be stored.
WMDifferent from passive storage, WM is active maintenance of goal related information relevent to a task in the face of proactive distractors. There is addition of mental “work” (cognitive processing) and its combination w/ “memory”. ( more than just STM), involves recognition & comprehension.
Limitation: memory component & control component
Outline
• Working memory (WM) and short-term memory (STM)
• WM, controlled attention, and fluid intelligence
• Role of pre-frontal cortex (PFC)
• Mapping from functions to structures
• Representation
WM is Capacity Limited
“Greater working memory capacity does not mean that more items can be maintained as active, but this is a result of greater ability to control attention,…ability to use attention to avoid distraction.”
-Engle RW
Memory capacity vs.
Cognitive control capacity
Model of WM, Engle
WM = STM + controlled attention
Three components:1. a store in the form of long-term memory traces active
above threshold2. processes for achieving and maintaining that activation3. Controlled attention (capacity limited, individual
performance difference arise)
Model of WM, Engle
Central Executive(working memory capacity, controlled attentions)
a. Achieve activation through controlled retrievalb. Maintain activation (to the extent that
maintenance activities are attention demanding).c. Blocking interference through inhibition of
distraction
Strategies, procedures for maintaining activation
a. Could be phonological, visual spatial, motor, auditory, etc
b. More or less attention demanding depending on the task and subject
Activated portion of long term memory
Magnitude of this link is determined by the extent to which the procedures for achieving the maintaining activation are routinized or attention demanding. Thus, it is assumed that, in intelligent, well-educated adults, coding and rehearsal in a digit span task would be less attention demanding than in a 4-year old children.
STM
LTM
Empirical Support
Two questions:
1) Is separate construct of STM and WM necessary?
2) Once the common variance to WM and STM is removed, do the WM residual variance (which should reflect controlled attention) correlate with the residual for general fluid intelligence?
Operation span
Reading span
counting span
backward span
forward span
Forward span w/ similar sounding word
WM
STM
COMMONGeneral fluid intelligence
Ravens standard progressive matrices test
Cattell fair test of intelligence
.77
.63
.61
.67
.79
.71
.81
.85
.49
.12
.91
.74
.29
Empirical Support
Engle et al (1999)
133 subjects performed 8 different tasks
WM and Fluid Intelligence
• Controlled attention is closely related to general fluid intelligence
• Performance task on WM task predicts performance on other cognitive tasks
e.g. performance on reading span task correlates well with reading comprehension
WM and Fluid Intelligence
Antisaccade Task
Require suppression of the natural tendency to saccade to the flashed cue.
WM span assessed on operation-span task.
cue target
Kane et al (1999)
AIdentification of target by pressing key
cue targetA
Identification of target by pressing key
Pro-saccade
Anti-saccade
WM and Fluid IntelligenceResult
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Kane et al (1999)
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Reflexive Eye Movement
Reaction Time
Eye movement not monitored in this case
WM and Fluid Intelligence
Stroop task Dots: Words: Colours:
• LONG BLUE
• AND RED
• VERY BLUE
• BUT GREEN
• HEAVY RED
• SHORT BLUE
• NEAR GREEN
• WITH BLUE
Result
WM and Fluid Intelligence
Dichotic listening task
Subjects repeat aloud words presented to one ear while ignoring information presented to the other ear. At some point, subject’s first name is spoken to the ignored ear.
Report whether they heard their name during the trial.
Result
20% high WM span subject reported65% low WM span subject reported
Conclusion
High WM span people suppressed distractor information better
Current WM Models
Baddeley & Hitch
Central Executive
Strategies, procedures for maintaining activation
STM
LTM
? Engle
Outline
• Working memory (WM) and short-term memory (STM)
• WM, controlled attention, and fluid intelligence
• Role of pre-frontal cortex (PFC)
• Representation • Mapping from functions to structures
PFC Anatomy
DorsolateralInput mainly from medial, dorsolateral cortical areas. (somatosensory, visuospatial information)
LateralInputs mainly from ventrolateral and ventromedial cortical areas (auditory, visual pattern information)
Segregation of functions? More on that later…
PFC Deficits in Human
Wisconsin card sorting
Results:
No difficulty learning the rule initially. (memory component)But once learning a rule, patient could not switch.
PFC Deficits in Human
Stroop task
London tower
Other cognitive tasks:Dots: Words: Colours:
• LONG BLUE
• AND RED
• VERY BLUE
• BUT GREEN
• HEAVY RED
• SHORT BLUE
• NEAR GREEN
• WITH BLUE
All these cognitive task involves a memory component
Q: deficit in memory component vs. executive control?
PFC Deficits in Human
Owen et al (1996)
Task:Find the hidden squares
Result:Normal controls: developed successful self-ordered search strategy
Temporal lob lesion patients: only failed on most difficult task
PFC lesion: failed on most easy task
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spatial
verbal
visual
Conclusion: prefrontal contribution to WM is the mediation of problem-solving strategies and not in memory per se.
PFC Deficits in Human
Other memory tasks
Inability to suppress irrelevent information, sensitive to proactive interference
Shimamura 1995
PFC Deficits in Human
Deficits in recalling temporal ordering, but no deficit in recognition.
Recall temporal-sequence
Milner & Petrides, 1984 Shimamura 1995
PFC Anatomy in Other Species
PFC Deficit in Nonhuman PrimatesWorking memory task Associative memory task
PFC lesioned primates:
Deficit in working memory task, but not in discrimination task
PFC lesioned primates also show deficit in spatial-delayed alternation task
PFC Deficit in Nonhuman Primates
Dias, Robbins & Roberts, 1996
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Lateral PFC Lesion: Slower to learn new criteria when the diagnostic dimension is changed.
Orbital PFC Lesion: Learn new criteria normally, slower to relearn.
PFC Deficit in Nonhuman Primates
After dorsolateral PFC lesion
Error on contralateral visual fieldPerformance decay with time
Funahashi , Bruce, & Goldman-Rakic (1993)
Fixation Point
Target
Delayed saccade task
Saccade!
PFC Neural Response
Anti-saccade task
Funahashi, Chafee, & Goldman-Rakic (1993)
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Error Trials
PFC Deficits
Dorsolateral- Spatial delayed response- Spatial delayed alternation task - No deficit in discrimination
Lateral- Object alternation- Delayed non-match to sample
Orbital- Deficits in olfactory, taste, visual and auditory discrimination- Discrimination reversal learning.
Outline
• Working memory (WM) and short-term memory (STM)
• WM, controlled attention, and fluid intelligence
• Role of pre-frontal cortex (PFC)
• Mapping from functions to structures
• Representation
Verbal storage
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storage
storage+processing
Verbal storage
Activation in left posterior parietal cortex (Brodmann’s area)3 frontal sites (Broca’s area)Left supplementary motor and premotor area
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storage
Storage+process
0- and 1-backItem recognition
2- and 3-backFree recall
Smith & Jonides, 1999 (review)
Visuospatial
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visual
spatial
Visuospatial
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Smith & Jonides, 1999 (review)
Spaital (blue)Object (red)
Some insights from Imaging studies
• Imaging studies show that working memory is mediated by frontal cortex and a collection of posterior regions differing in the types of information maintained.
• Posterior cortical regions seem to specialize in the type of information held in working memory
• Frontal area may have a special role in integrating different type of information
Outline
• Working memory (WM) and short-term memory (STM)
• WM, controlled attention, and fluid intelligence
• Role of pre-frontal cortex (PFC)
• Mapping from functions to structures
• Representation
WM Representation
Domain general vs. Domain specific?
Baddeley & Hitch
Central Executive
Strategies, procedures for maintaining activation
STM
LTM
Engle
Domain General?
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Conclusion: More than half of the neuron (64/123) contain both “what” and “where” information
Rao, Rainer, & Miller (1997)
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But wait…
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Wilson, Scalaidhe, Goldman-Rakic 1993
Lateral PFC24/31 selective for pattern6/31 selective for both1/31 selective for spatial information
Conclusion: segregation of “what” (lateral) and “where” (dorsolateral)
Cue Delay Response
Thank you!
Backup slides
PFC Neural Response
Primate performing a delayed response task
Milner & Petrides (1984)
PFC Neurons
PFC Neural ResponseCue-delay-saccade
Funahashi , Bruce, & Goldman-Rakic (1989)
Q: memory of cue vs. motor preparation?
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PFC Neural ResponseQuintana & Fuster (1992)
Dissociation of memory of cue from motor preparatory cue
PFC Neural Response
Rainer Asaad & Miller (1998)
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Delayed match-to-sample task
SpatialJonides, Smith, Koeppe, Awh, Minoshima, Mintun. (1993)
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Areas for spatial memory task
Domain General?
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Suchan, Linnewerth, Koster, Daum, & Schmid (2006)
Cross-modal processing