psy 368 human memory memory implicit memory. outline implicit versus explicit memory definitions...

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”

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”


Examples

•Study: bird, house, balloon, horse, rocket, dolphin

• (maybe levels of processing, or divided attention manipulation)

•Tests:• Picture fragment naming


• 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


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


• 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


• Test• Word stem completion• 2 instructions

• Use words from earlier list

• First word you think of

Tulving, Schacter, & Stark (1982): Forgetting Effects


• 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)


• 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)


• 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)


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.


• 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


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)


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


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


• 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

• 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


• 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


• 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

psy 368 human memory memory implicit memory. outline implicit versus explicit memory definitions...

Documents

explicit memory slide

memory performance

implicit tasks

explicit memory expts

study tasks

type of memory test

indirect tests of memory

awareness slide