Long-term Memory:

Explicit & Implicit memory

Explicit vs. Implicit memory

Explicit memory

Effortful, conscious recollection

Memory tasks: Recall; Cued-recall; Recognition

Implicit memory

Remembering without awareness

Memory tasks: Word-stem or word-fragment;

Perceptual identification; Repetition priming

Procedural memory

Implicit memory for skills and motor movements

Implicit learning

Learn w/o awareness

Implicit measures

Word-stem or fragment completion

See list of words (e.g. rose)

Fill-in with first thing that comes to mind (e.g. r__e)

Perceptual identification

See list of words or pictures

Stimulus flashed (38ms), asked to identify it

Repetition priming

See list of words (e.g. fruit)

Judge if correct (e.g. fruit – apple or fruit – dog)

Faster when previously exposed to word

Study: read pairs

BALANCE – CHAIR

MOLD – BREAD

KIND – STICK

RIPE – APPLE

DELICATE – FRAGILE

COVERING – BLANKET

KNEE – BEND

JAIL – STRANGE

BED – SHEET

DRYER – BLOCK

TABLE – WOOD

CUP – MOVIE

DOOR - BOOK

Test completion

Explicit vs. Implicit INSTRUCTIONS Retrieval process (not storage)

Test item with same related context MOLD – BR; RIPE – AP; BED – SH; CUP – MO

Test item with same unrelated context KIND – STI; JAIL – STR

Test item with different context TOWN – BL; DETAIL – FRA; BELIEF – CHA

Test item with no context BLA; WO; BOO

Distractors ABS; FLA; DU; THI

Tulving (1962)

Study: Ss presented with 96 words

Test: Implicit word-completion test

Fill-in fragment to create a word w. first word that comes to mind

Explicit recognition test IV: tests given 1hr and 7days after study session

Results: Implicit test:

Previously seen fragments: 47% completed New fragments: 30% completed No change in scores over time

Explicit test: 1hr recognition 60%; 7 days 22% acc

Conclusion: Implicit memory for words for up to 7days

Parkin & Streete (1988)

Warrington & Weiskrantz (1968)

Can implicit memory performance improve for amnesic patients?

Method

Ss: Korsakoff’s patients

Picture identification

Same task for 3 days

Results

Conclusions Implicit memory intact

Amnesic patient vs. control

Warrington & Weiskrantz (1970) Explicit

Free recall

Recognition

Implicit

Perceptual identification

Fragment-completion

Graf, Squire, & Mandler (1984) Explicit

Free recall

Cued-recall

Implicit

Word-completion

Warrington & Weiskrantz (1970)

5

10

15

20

Free recall Recog PID Frag-Compl

Control

Amnesia

Explicit Implicit

Graf, Squire, & Mandler (1984)

Free recall

Word-completion

Jacoby & Witherspoon (1982)

Anterograde amnesia patients

Study homophones

“book-read” OR “saxophone-reed”

Test

Recognition test

Generate test: listen and write down homophone

Word fragment test: fill-in “R_ _ D”

Results:

No explicit memory

Previous experience influenced spelling performance

Evidence of intact implicit memory

Jacoby (1983)

Study:

No context: “woman”

Context: “man-woman”

Generate: “man –”, say

woman

Test:

Explicit: recollection

Implicit: perceptual

identification

Famous or non-famous? Don Imus

Lucca Richards

Minnie Pearl

Sebastian Weisdorf

Valerie Marsh

Bonnie Blair

Tim Robbins

Daniel Tucker

Harold Evans

Roger Clemons

Charlie McFadden

Linda Whalen

Pierce Brosnan

Adrian Marr

Chris Rock

Jon Secada

F

NF

F

NF

NF

F

F

NF

NF

F

NF

NF

F

NF

F

F

Jacoby, et al. (1989)

Probability judge as

famous:

New famous: 63%

New nonfamous: 32%

Old nonfamous: 38%

Ironic effects of implicit memory

False fame effect

Effect of familiarity on recollection

Explicit and implicit memory can work together for

better memory

Or can work against each other to create errors

Propaganda effect

More likely to accept information as true if

previously exposed to it

Mere exposure effect

Like stimulus more if previously exposed to it

Process dissociation procedure (PDP) Jacoby (1991); Jacoby, et al. (1993)

Study list of words

Full attention vs divided attention

Word-completion (old and new stems)

Inclusion: recall or guess words from list

Exclusion: do not use prior study words

PDP: (calculated on old word answer probability)

Inclusion: Recollection (R) or familiarity

R + F - RF

Exclusion: familiarity

F (1 – R) = F – RF

R = Inclusion – Exclusion; F = Exclusion / (1 – R)

Conclusions

Full vs divided: R = .25 vs .00; F = .47 vs. .46

Case studies: Amnesia http://www.liveleak.com/view?i=fd0_1261475829

• H.M. (1926 – 2008) • “Every day is alone.”

• Background • Brain surgery (1953) due to

epileptic seizures

• Temporal lobotomy (removal of both hippocampal areas)

• Anterograde amnesia

• Cognitive findings • STM intact; LTM deficit

• Implicit memory intact; explicit memory deficit

• Intact repetition priming

• Procedural memory intact

• Intact problem solving

Clive Wearing

• Dense retrograde and anterograde amnesia patient

• Born in 1938, contracted viral encephalitis in 1985

• Prior to illness a very successful musician

• Husband to 2nd wife; has children from 1st marriage

• What is he (in terms of cognition) able and not able to do?

• BBC 2005 – “Man with the 7s memory”

• 20 yrs post injury – 67 yrs old

• http://www.youtube.com/watch?v=wDNDRDJy-vo&feature=related

• 1998 documentary

• 13 yrs post injury – 60 years old

• http://www.youtube.com/watch?v=Lu9UY8Zqg-Q&feature=related

• http://www.youtube.com/watch?v=xCyvzI2aVUo&fea

• http://www.youtube.com/watch?v=9BrCBq2FY_U&feature=related

Underside of brain

Main structures of medial temporal lobe (MTL)

Brain areas associated with memory

Explicit memory

Medial temporal lobe

Hippocampus

Perirhinal cortex

Implicit memory

Striatum for procedural skills

Neocortex for priming tasks

Semantic memory

Left inferior prefrontal cortex

Neocortex - widely distributed

Episodic memory

Right anterior and dorsolateral prefrontal cortex

Medial temporal lobes

Case studies & brain areas

H.M.: anterograde amnesia (retrograde 2yr) STM intact; LTM deficit; intact implicit memory

Bilateral medial temporal lobes

Posterior region of hippocampus intact

R.B.: anterograde (retrograde 1yr) Memory deficits less severe than H.M.

Lesion to CA1 pyramidal cells (bilateral) of hippocampus

K.C.: retrograde and anterograde amnesia STM and semantic intact; no episodic memory

Medial temporal lobe, frontal parietal, occipital

Greater damage on left side

M.S.: Intact explicit; impaired implicit Right occipital lobe – areas 18 and 19

Korsakoff’s syndrome Dorsomedial nucleus of thalamus & mamillary bodies

Medial temporal lobe

• Medial temporal lobe NOT responsible for… • Implicit memory or procedural memory

• Not where LTM are stored

• STM or WM

• Medial temporal lobe IS responsible for… • Conscious LTM formation

• Consolidation: Strengthening association

• Transfer of info from STM to LTM

• Problems and other theories • Based on case studies

• MTL for encoding or retrieval?

• Subtraction technique with imaging

Longitudinal study of implicit and explicit

memory in older adults Fleishman et al. (2004)

Cross-sectional vs longitudinal studies

Participants: “Religious Orders longitudinal study” – older nuns, priests, brothers

N = 161 w/o dementia; 4 annual evaluations

Materials: Explicit tasks: 4 tests of story retention, 3 word list

Implicit tasks: word-stem completion; category-exemplar production, word identification; picture naming

Results: Explicit: ~0.05 unit decline per year for 75yr old; ~0.1 unit decline per year for 85yr old (decline related to age)

Implicit: no decline per year or by age