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PSY 368 Human Memory
Memory Implicit memory
Outline
• Theories accounting for Implicit vs. Explicit memory
• Experiment 2 Signal detection analysis
• Process-dissociation procedure, working through our example (probably not time, so after break)
Memory Tasks
indirect direct
incidentalimplicit memoryexpts.
Levels of Processing
expts.
intentional? explicit
memoryexpts.
Test Instructions
Study Instruction
s
Implicit Memory: Often defined as "memory without awareness”
• Also “Non-declarative” & “procedural” (Squire, Knowlton, & Mesen, 1993)
Implicit/Explicit Dissociations
• Many demonstrations of different effects depending on whether implicit or explicit tasks are used• Amnesic patients• Levels of processing manipulations
• Pleasantness vs. vowel comparisons
• Generation effect• Divided attention• Picture-word superiority
• Note. Most of we’ve talked about concern repetition priming effect (study “horse” and respond “horse”)
• Four major approaches have been proposed• The Activation view• Multiple Memory systems view• Transfer appropriate processing view• Bias View
Accounting for Implicit/Explicit Dissociations
• Four major approaches have been proposed• The Activation view• Multiple Memory systems view• Transfer appropriate processing view• Bias View
Accounting for Implicit/Explicit Dissociations
The Activation View
• Priming on indirect tests is attributable to the temporary automatic activation of preexisting representations.• Because it is automatic, it occurs without elaborative
processing and thus has little to no contextual information
• Weak Point • Can not explain priming over long time periods
• Some implicit priming over days or even weeks (e.g., Sloman, et al, 1988)
• Can not explain priming without pre-existing representations
• The least popular of the four views
• Four major approaches have been proposed• The Activation view• Multiple Memory systems view• Transfer appropriate processing view• Bias View
Accounting for Implicit/Explicit Dissociations
Multiple Memory Systems
• Many dissociations between direct and indirect tests of memory arise because the tests tap different underlying memory systems.
Squire (1987)
Multiple Memory Systems
• Many dissociations between direct and indirect tests of memory arise because the tests tap different underlying memory systems.
Tulving (1984)
Multiple Memory Systems
• What is a system?• It is NOT a process• It is NOT a task
• Some different ways that systems have been defined
Schacter and Tulving (1994)
Multiple Memory Systems
• What is a system?• Functional Dissociations
• Task that taps into system A that has no effect (or a different effect) in System B
• Different neural substrates• System A involves different brain areas than System B
(brain damage cases and neural imaging studies)
• Stochastic independence• Performance on System A task uncorrelated with
performance on a System B task
• Functional incompatibility• Could involve different rates of forgetting
• Function carried out by System A can not be done by System B
Schacter and Tulving (1994)
Multiple Memory Systems
• What is a system?
Schacter and Tulving (1994)System Other Name Subsystems Characteristics
Procedural Nondeclarative Motor skills Non-conscious operation(indirect)
Cognitive skills
Simple conditioning
Simple associative learning
Perceptual representation
Nondeclarative Visual word form
Auditroy word form
Structural description
Primary memory
Working memory Visual Conscious operation(direct)
Auditory
Semantic Generic Spatial
Factual Relational
Knowledge
Episodic Personal
Autobiographical
Event memory
If you “know how to do something”
Allows you to automatically recognize things
See earlier in the semester
Factual information (chpt 10)Memory of events
• Brain areas• Brain imaging studies
found that different areas of the brain are used when completing implicit and explicit tasks
• Note: more than one structure involved in each type of memory
Buckner et al (1995) PET study
Multiple Memory Systems
• Brain areas• Brain imaging studies
found that different areas of the brain are used when completing implicit and explicit tasks
Gabrieli et al (1995) Case study of MS
MRI of MS’s brain
• Intact performance on explicit tests of recognition and cued recall
• Intact performance on implicit test of conceptual memory
• Impaired performance on implicit tests of visual perceptual memory• Suggests a specific deficit
in visual implicit memory
• Studied lists of words
• Perceptual identification and recognition task
Multiple Memory Systems
• Brain areas• Different kinds of implicit
tasks seem to involve different areas• Perceptual vs.
conceptual tasks appear to use different brain areas
• Conclusion: brain area involvement may be a function of type of processing and type of memory
Buckner & Koutstall (1998) fMRI study
Multiple Memory Systems
• Stochastic Independence• Hayman and Tulving (1989)
• Measure correlation between explicit and implicit task performance
• If not correlated (independent), then tasks measure different processes
Multiple Memory Systems
• Forgetting• Tulving et al. (1989) showed a difference in
forgetting rate for recognition and fragment completion
• Confirmed with other tasks (stem completion)
• Strengths• Fits well with dissociations found
• In patients• In experiments
Multiple Memory Systems
• Problem• Hard to find consensus on what the systems are• May be “too easy” to posit a new system
• Four major approaches have been proposed• The Activation view• Multiple Memory systems view• Transfer appropriate processing view• Bias View
Accounting for Implicit/Explicit Dissociations
• The key to good performance is similarity of processes involved in encoding vs. retrieval, be it implicit or explicit, perceptual or conceptual test
• Implicit and explicit may refer to different processes, yet the key to performance is matching processes.
Processes at encoding
Processes at test
Overlap determines retrieval success
Transfer Appropriate Process
A consequence: conceptual processing is the common core in free recall and implicit conceptual tasks, hence performance on these two types of task should be equal.
Transfer Appropriate Process
Assumes:• Performance depends of match between
processing at study and processing at test.Analogous to encoding specificity.
• Two-types of Processes (Jacoby, 1990)• Data-driven (perceptual) – processing of
physical features.• Conceptually-driven (semantic) – processing
for meaningTypically confounded, however, it is possible to un-confound test-type from process-type
• Jacoby (1990) proposed that implicit vs. explicit memory is confounded with two different kinds of memory processes (associated with two kinds of information)
Mixing Implicit and Explicit Effects
Memory system
Mode of Processing
Declarative(Episodic)
Procedural(Priming)
Perceptual(Data-driven)
Perceptual identification
Word Fragment
Completion
Meaning based(conceptually-driven)
Free RecallRecognition
Data-driven
(Perceptual):
• fragment completion
• stem completion
• anagram completion
• lexical decision
• perceptual identification
Conceptually-driven
(Semantic):
• word association
doctor ??
• category-instance generation“name a mammal”
• general knowledge“The capital of the US is …?”
Transfer Appropriate Process
• Goal to demonstrate• data-driven processing can affect direct tests• data-driven processing do not necessarily
affect indirect tests
Blaxton (1989)
Transfer Appropriate Process
Data-driven Conceptually-driven
Direct Graphic-cuedRecall
Free Recall
Indirect FragmentCompletion
GeneralKnowledge
Target word: bashful• graphic-cued recall: looks like “bushful”• free recall• frag completion: b_sh_u_• General knowledge: “Name one of the 7 dwarfs”
Blaxton (1989)
Data-driven Conceptually-driven
Direct Graphic-cuedRecall
Free Recall
Indirect FragmentCompletion
GeneralKnowledge
Transfer Appropriate Process
S’s saw or heard lists of words (key IV here)
Predictions• Systems view: modality match should affect only
indirect tests (if indirect tap separate system, then modality should affect them in the same way)• for both implicit tests: visual > auditory
• for both explicit test: visual = auditory
Blaxton (1989)
Transfer Appropriate Process
Data-driven Conceptually-driven
Direct Graphic-cuedRecall
Free Recall
Indirect FragmentCompletion
GeneralKnowledge
Same pattern of results regardless of modality
Visual better than auditory for both
Predictions• TAP View: modality match should affect data-
driven tasks only. (priming depends on match between study/test processing match & not on indirect vs direct): • for both data-driven tests: visual > auditory• for both conceptually-driven tests: visual = auditory
Blaxton (1989)
Transfer Appropriate Process
Data-driven Conceptually-driven
Direct Graphic-cuedRecall
Free Recall
Indirect FragmentCompletion
GeneralKnowledge
Visual should be better than auditory
Visual and auditory should be about the same
ResultsPriming Effect (V > A) for
data-driven tasks only:
• indirect: frag completion
• direct: graphemic-cued recall
Not all indirect tests display priming effect.
• Gen Know (indirect, conceptual): V = A
Blaxton (1989)
Transfer Appropriate Process
ConclusionsSupport view that
processing rather than system is what is important
• Four major approaches have been proposed• The Activation view• Multiple Memory systems view• Transfer appropriate processing view• Bias View
Accounting for Implicit/Explicit Dissociations
The Bias View
• Proposed to account for repetition priming effects. • Prior presentation of an item can bias subsequent
processing of the item on later presentations (if you see it once, you are more likely to interpret in the same way later)• Multiple systems attributes this to 3 separate systems, but
doesn’t really offer an explanation
• TAP’s answer is considered circular (you respond faster the second time because of transfer appropriate processing, which was developed to account for priming effects)
The Bias View
• Bias View’s account for repetition priming effects.
1. First See one of old woman and young woman
2. Second See ambiguous woman
3. People are more likely to interpret the ambiguous picture as the same person as the unambiguous picture
1. First See Old Woman Young Woman
2. Second See Ambiguous -> Old Woman
Ambiguous -> Young Woman
• Bias entails both cost and benefits• Cost : There will be an advantage if prior
processing is appropriate for the current task• Benefits : There will be a disadvantage if prior
processing is inappropriate for the current task
Comparing the theories
• Strengths• Processing perspective• No “need” for separate
systems (true of Bias view too)
• Bias View may be seen as a complement to the TAP view
• Weaknesses• Doesn’t explain impact of
conscious awareness• Trouble with finer grain
distinctions between tasks
TAP Multiple Systmes• Strengths
• Good fit for deficit data (but may be too easy to propose “new systems”)
• Weaknesses• Has troubles with some
data showing differential decline in memory performance with aging
• Sometimes difficult to make specific predictions in advance
Implicit Memory Summary
• Implicit memory is memory without awareness.• Implicit and explicit tasks are not “process pure”• PDP offers a measurement method for processes
• Implicit memory is different memory from explicit memory by experimental dissociations.
• There is 4 main accounts for implicit memory• Probably a complex relationship between systems and
processes
Experiment 2
• Recall that for experiment 2 you each collected data from three participants.
• IV – levels
• Prediction: our instructions would lead participants to shift their criterion for what counts as old vs. new.
• Signal detection analysis
Signal Detection Theory
• Recognition accuracy depends on:• Whether a signal (noise/target memory) was
actually presented• The participant’s response
• Thus, there are four possible outcomes:
• Hits• Correctly reporting the presence of the signal
• Correct Rejections• Correctly reporting the absence of the signal
• False Alarms• Incorrectly reporting presence of the signal
when it did not occur• Misses
• Failing to report the presence of the signal when it occurred
CORRECT
INCORRECT
Signal Detection Theory
• Calculating d’ and C (or β)• Discriminability (d’):
• Step 1) Look up the z-score for the average Hit and False Alarm rates.
• Step 2) Apply the formula d’ = zHIT – zFA, where zFA is the z-score for FAs and zHIT is the z-score for Hits.
• Criteria C (or β):• Take the negative of the average of
zHIT and zFA. This is the criterion value C. • Remember that positive C values
indicate a conservative response bias, while negative C values indicate a liberal response bias.
http://memory.psych.mun.ca/models/dprime/
Experiment 2Target Lure
“Old” Hit15.050.75
False Alarm2.480.12
Neutral
Target Lure
“Old” Hit12.050.60
False Alarm1.140.06
Target Lure
“Old” Hit16.950.85
False Alarm4.380.22
Conservative
Liberal
N=21 per condition
Total possible hits or false alarms = 20AveragesProportions (avg/20)
Experiment 2Target Lure
“Old” Hit15.050.75
False Alarm2.480.12
Neutral
Target Lure
“Old” Hit12.050.60
False Alarm1.140.06
Target Lure
“Old” Hit16.950.85
False Alarm4.380.22
Conservative
Liberal
d’ = 1.85C = 0.25
d’ = 1.81C = 0.65
d’ = 1.81C = -0.13
http://memory.psych.mun.ca/models/dprime/
Experiment 2
Neutral
Conservative
Liberal
d’ = 1.85C = 0.25
d’ = 1.81C = 0.65
d’ = 1.81C = -0.13
stimulus intensity
pro
babili
ty
Noise
Signal(remember)
d’
Experiment 2
Neutral
Conservative
Liberal
d’ = 1.85C = 0.25
d’ = 1.81C = 0.65
d’ = 1.81C = -0.13
stimulus intensity
pro
babili
ty
Noise
Signal(remember)
OldNew
- Criterion +
Experiment 2
Neutrald’ = 1.85C = 0.25
stimulus intensity
pro
babili
ty
Noise
Signal(remember)
OldNew
- Criterion +
Experiment 2
Conservatived’ = 1.81C = 0.65
stimulus intensity
pro
babili
ty
Noise
Signal(remember)
OldNew
- Criterion +
Experiment 2
Liberal
d’ = 1.81C = -0.13
stimulus intensity
pro
babili
ty
Noise
Signal(remember)
OldNew
- Criterion +