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PSY 368 Human Memory
Memory Implicit memory
Outline
• Implicit versus explicit memory• Definitions• Dissociations
• Process-dissociation procedure
• Theories accounting for Implicit vs. Explicit memory
Demo
• PDP exercise
• Pass out sheets and read instructions
• Collecting the data: count up number of study words that were written down for each task, write this on your sheet
Pleasantness Vowels
Inclusion
Exclusion
Questions to Think About
• Does the type of memory test matter?
• We’ve seen that the answer is yes. So far have covered intentional vs. incidental, and recall vs. recognition. These have largely been what are considered direct tests of memory (know that it is a memory test related to something earlier).
• There are also indirect tests of memory (don’t know that the test is related to memory/to something done earlier)
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)
Perceptual TasksWord identification
Word stem completion
Word fragment completion
Degraded word naming
Anagram solution
Lexical decision
Implicit Memory Tasks
Non-Verbal Tasks
Picture fragment naming
Object decision task
Possible/impossible object decision
Conceptual TasksWord association
Category instance generation
Answering general knowledge questions
Often defined as "memory without awareness”
Perceptual TasksWord identification
Word stem completion
Word fragment completion
Degraded word naming
Anagram solution
Lexical decision
Implicit Memory Tasks
Non-Verbal Tasks
Picture fragment naming
Object decision task
Possible/impossible object decision
Conceptual TasksWord association
Category instance generation
Answering general knowledge questions
Often defined as "memory without awareness”
Examples
•Study: bird, house, balloon, horse, rocket, dolphin• (maybe levels of processing, or divided attention
manipulation)
•Tests:• Lexical decision – bronk ‘no’ - - horse ‘yes’ -- …• Stem Completion - hor- “horde” vs “horse”• Fragment Completion - h_r_s_ “hares” vs “horse”• Category exemplar production - Animal-? “pig” vs
“horse”• Word Association - saddle - ? “leather” “bags”
“horse”
Implicit Memory Tasks
Examples
•Study: bird, house, balloon, horse, rocket, dolphin
• (maybe levels of processing, or divided attention manipulation)
•Tests:• Picture fragment naming
Implicit Memory Tasks
• Warrington and Weiskrantz (1968, 1970, 1974) showed differences in memory performance for amnesic patients
Do amnesics have memory?
• Amnesic patients• Can’t complete typical
explicit memory tasks• Typically don’t even
remember seeing a list
• Performance on implicit tasks is similar to control participants
• The Search for Dissociations• Suggests that these tasks rely on different forms
of memory• Dissociation = different effects of an IV on the
two test types (similar to the recognition vs. recall dissociations)
Explicit vs. Implicit Memory
• Study tasks• Read aloud w/o context
• COLD
• Read w/ context• hot – COLD
• Generate from context• hot - ???
• Test tasks• Recognition • Perceptual Identification
Explicit vs. Implicit Memory
Jacoby (1983): Generation Effect
Opposite pattern of results with implicit task
Roediger & Weldon, (1987)
• Study tasks• Lists of pictures and
words
• Test tasks• Free recall of pictures
and words• Word fragment
completion• Priming effect:
compared studied vs. unstudied completions
Explicit vs. Implicit Memory
• Study• Full attention
• read word as quickly as possible
• Divided attention• Name the color the word is presented in
Rajarm, Srinivas, & Travers (2001) Attention Effect
Explicit vs. Implicit Memory
• Test• Word stem completion• 2 instructions
• Use words from earlier list
• First word you think of
Tulving, Schacter, & Stark (1982): Forgetting Effects
Explicit vs. Implicit Memory
• Study• List of words
• Test• Word fragment
completion• After 1 hr. & 7 days later
• Memory score = priming effect• Compare fragment
completions of old vs. new items
• Tasks are not “process pure” (Jacoby, 1991)• Indirect measures of memory may be
“contaminated” by intentional uses of memory• E.g., in stem completion task, subjects might
remember items from previous list and use them to complete the stems
• Direct measures may be influenced by unconscious or automatic influences (Jacoby, Toth, & Yonelinas, 1993)
• Process-Dissociation Procedure was developed to separate automatic (unconscious) and conscious processes
Mixing Measures
Jacoby (1991)• Read a list of words – List 1• Hear a list of words – List 2• Two recognition tests:
• Both tests include List 1, List 2 and novel words.• Inclusion = complete task with studied or any
item• Respond “old” if word was on either list.
• Exclusion = complete task with item NOT studied (exclude studied items)• Respond “old” only if word was on List 2.
Process Dissociation Procedure
• Can calculate C and A for each condition in the experiment• C = (Proportion of studied items in inclusion) -
(Proportion of studied items in exclusion)• A = (Proportion of studied items in exclusion) / (1-C)
• The C and A values are estimated as proportions - values between 0 and 1.0
• Data• Proportion of studied items in inclusion = C + (1-C)
(A)• Proportion of studied items in exclusion = (1-C)(A)
Jacoby (1991)
Process Dissociation Procedure
• Exclusion: Respond “old” only if word was on List 2.• Use equations to calculate conscious (C) and automatic
(A) memory from target performance on the tasks• P(old) = A(1-C)• Subject will only respond “old” to List 1 words if two
things happen:• A: The automatic process responds “old” due to a feeling of
familiarity
• (1-C): The intentional process fails to recognise the word (if it had, it would recall it was from List 1)
Jacoby (1991)
Process Dissociation Procedure
• Inclusion: Respond “old” if word was on either list.• Use equations to calculate conscious (C) and
automatic (A) memory from target performance on the tasks
• P(old) = C + A (1-C) • If either process concludes “old”, the subject will
respond “old”• A: Automatic process will also have a certain probability of
concluding “old” for List 1 words• C: Conscious (intentional) process will have a certain
probability of concluding “old” for List 1 words
Jacoby (1991)
Process Dissociation Procedure
Jacoby (1991)• Read a list of words – List 1• Hear a list of words – List 2• Inclusion = Respond “old” if word was on either list.• Exclusion = Respond “old” only if word was on List 2.
Process Dissociation Procedure
• Inclusion test P(old) = 0.48• Exclusion test P(old) = 0.37*
• C = Inclusion – Exclusion = 0.11• A = Exclusion / (1-C) = 0.37 / 0.89 = 0.42
*in exclusion condition, “OLD” are errors
Jacoby, Toth, & Yolelinas (1993): Attentional effects
Process Dissociation Procedure
Study: read words• full attention• divided attention – read aloud while listening for odd
numbers
Task: stem completion:• inclusion: complete with list word or guess
• green stem inclusion (may use as a cue from list)
• exclusion: complete with new words only• red stem exclusion (complete with word not from list)
Jacoby, Toth, & Yolelinas (1993) (Exp 1b)
Process Dissociation Procedure
Divided attention:• Inclusion task: P(old)• Exclusion task: P(old) Results:• Inclusion: div (46%) <
full (61%)• Exclusion: div (46%) > full
(36%)
Interpretation:• div attention knocked out
recollection• recollection accuracy in
both conditions
Process Dissociation Procedure
Conscious Automatic
Full .25 .47
Divided .00 .46
Jacoby, Toth, & Yolelinas (1993) (Exp 1b)Conclusions•Conscious recollection greatly reduced under divided attention condition
Toth, Reingold, and Jacoby (1994): Levels of Processing
Conscious Automatic
Deep .27 .42
Shallow .03 .45
Study• Pleasantness
rating• Shared vowels
Test• Stem completion
taskStudy• Read word• Say aloud missing
word in sentence
Test• Stem completion
task
Conscious Automatic
Read .21 .48
Generate .34 .28
Process Dissociation Procedure
• Four major approaches have been proposed• The Activation view• Multiple Memory systems view• Transfer appropriate processing view• Bias View
Accounting for Implicit and Explicit Effects
• STOP HERE FOR TODAY
• Insert slide here
Activation view
• Many believe there are different systems of memory
• What is a system?• Could involve different brain areas (amnesia)• Could involve different rates of forgetting
Memory Systems
Squire (1987)
Memory Systems
Memory Systems
Squire (1987)
Memory Systems
• Brain areas• Brain imaging studies found that different areas of the
brain are used when completing implicit and explicit tasks
• But there isn’t just one structure involved in each type of memory
• And different kinds of implicit tasks seem to involve different areas
• Conclusion: brain area involvement may be a function of type of processing and type of memory
Memory Systems
• Forgetting• Tulving et al. (1989) showed a difference in
forgetting rate for recognition and fragment completion
• Confirmed with other tasks (stem completion)
Memory Systems
• Forgetting• But these studies looked at long-term
forgetting (days, months)• Didn’t follow RIC or use PDP
Memory Systems• Forgetting
• More recent studies showed no difference in forgetting rates for implicit/explicit stem completion
• Used RIC and PDP
Memory Systems
Memory Systems
• 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
Processing View• Based on TAP view
• Tasks used for implicit memory usually have perceptual cues • app-• a_p_l_
• Explicit tasks often are more conceptual
Processing View• Differences found between implicit/explicit
tasks could reflect perceptual/conceptual differences
• Tested by Blaxton (1989)
Processing View
Explicit Implicit
Perceptual
Task
???? Stem and fragment completion
Conceptual
Task
Free recall ????
Processing View
Explicit Implicit
Perceptual
Task
Graphemic cued recall
Stem and fragment completion
Conceptual
Task
Free recall Gen. Knowledge
Processing View• Read/Generate study
• Compared tasks across both dimensions
Processing View• Shows that match between study and test
processing is more important
• Weldon & Roediger (1987) found different picture superiority effect for two implicit tasks
Summary of Implicit/Explicit• TAP may be more important than
memory process
• Implicit and explicit tasks are not “process pure”
• PDP offers a measurement method for processes
• Implicit/Explicit memory show dissociations on several variables
Explicit vs. Implicit memory• Generation effect (Java, 1993) - found for
explicit but reversed for implicit
• Subjects studied words - read or generated
• Completed implicit and explicit stem completion
Explicit vs. Implicit memory
• Level of Processing (Roediger et al., 1992) - found for explicit but not implicit
• Subjects studied words - pleasantness vs. letter tasks
• Completed implicit and explicit stem and fragment completion
Explicit vs. Implicit memory
• Attention (Mulligan, 1998) - dividing attention at study reduces explicit not implicit
• Study - just study words vs. study words and do extra task
• Test - implicit/explicit fragment completion
Explicit vs. Implicit memory
• Forgetting (Tulving, Schacter, & Stark, 1982) - difference in forgetting rates for explicit/implicit task performance
• Looked at performance for recognition and implicit fragment completion at 1 hr and 2 days
• Recognition performance declined, but implicit task performance did not
Processing View• Studied pictures and words
• Tested with picture fragment naming and word fragment completion
• Picture fragment naming = name degraded picture with first thing it looks like
• Processing View
Processing View
• Supports the perceptual/conceptual distinction
• But distinction not always shown
• Weldon and Coyote (1996) compared picture/word memory with category production tasks
• Found picture superiority for explicit category production, but no difference for implicit task
• Hayman and Tulving (1989)
• Measure correlation between explicit and implicit task performance
• If not correlated (independent), then tasks measure different processes
Stochastic Independence
Dual-process theories
• Process Dissociation Procedure (Jacoby, 1991)• Task:
• Participants study two sets of items in different contexts• Two different recognition tests follow:
• Inclusion Condition:• Say “yes” if they recognize an item from either context• Correct recognition = Recollection + Familiarity
• Exclusion Condition:• Say “yes” only if they recognize an item from one of the
two contexts • Familiarity = False alarms in exclusion condition
• Recollection = Inclusion’s correct recognition minus Familiarity
Dissociating Recollection and Familiarity
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