Transcript No Slide Title

IMPLICIT MEMORY: A “HIDDEN
WORLD?”
• Tasks and terms
– “indirect” (vs. direct) memory tests: no
memory judgments; assess effects of
prior exposure on
• Fragment completion
• Perceptual identification
• Repetition and “feature” priming
• Other decisions and actions
– Implicit (vs. explicit) memory: the
memory systems and/ or processes that
(largely) mediate performance in
indirect memory tests
• Contrast to:
– Incidental learning: no reference to
memory test during study
– Implicit learning: of patterns or
correlations without intent or awareness
AGNOSTIC
ALMANAC
GAZETTE
GRANARY
PLANKTON
QUARTET
BACHELOR
BEHAVIOR
IDEOLOGY
LAGGARD
RUFFIAN
SILICON
BROCCOLI
CLARINET
LITHIUM
MYSTERY
THEOREM
PENDULUM
NOCTURNE
MIGRAINE
Anecdotal Examples of Implicit
Memory
• Cases of “unconscious plagiarism”
– George Harrison and the Chiffons
– Freud’s “discovery” of universal
bisexuality, and Fliess’ reaction
• Use of expert knowledge
– Peter Bonyhard: helped IBM develop
mag-resist disk drives, barred from
working with competitor Seagate
• Implicit memory for traumatic events
– Amnesia for rape on a brick path, but
words “brick” and “path” come to mind
– Global amnesia, home is unfamiliar, but
“recently dreamed of that house”
• Implicit memory for words spoken
during anesthesia
– Kilstrohm & Schacter (1990)
• 25 word pairs, increased “free
association” two weeks later
SI__C_N
_DEO_O__
_UFFA__
B__CC__I
___NK_ON
NO____NE
AL__N__
_AZ__TE
__TH_UM
BE__VI__
_U_R_ET
G_A__RY
_L_R__ET
_IGR__NE
_G_O_TI_
L_G__RD
_E_D_L_M
_H_O_EM
BA__E_OR
_YS__RY
THE SEARCH FOR
DISSOCIATIONS
• Stochastic
– Performance in IM and EM tasks given
same study is uncorrelated
• Functional
– Weak: variable X influences one kind of
test, (not) the other
• Levels of processing
• Modality
– Strong: variable X has opposite effects
on IM and EM tests
• Read versus generate (Jacoby 83)
• Population
– A functional dissociation where X is a
group factor (amnestics vs. controls)
• Reverse Association
– X affects A and B the same, Y has
opposite effects on A and B, in same
data set (Dunn & Kirsner, 1988)
A CAPSULE HISTORY of
IMPLICIT MEMORY
• Late 19th century
– Dissociations in the clinic (Dunn, 1845;
Claparede, 1889)
– Savings without explicit memory
(Ebbinghaus, 1885)
– Habit versus memory (James, 1890;
Bergson, 1911)
• 1970’s
– Controlled studies of priming in
amnestics
• HM can learn motor skills
• Amnestics show normal
fragment-completion priming
(Warrington & Weiskrantz, 1970)
recogn
fragment ID
Amnestics
.42
.46
Controls
.75
.45
• Demonstrations of implicit memory
in normals
– Jacoby & Dallas (1981):
• Depth affects recognition, not priming
• Modality affects priming, not recog
– Tulving, Schacter & Stark (1982):
• much less forgetting for implicit tasks
– Jacoby (1983):
• Opposite effects of context and
generation on implicit and explicit tasks
No context
XXX-COLD
context
HOT-COLD
generate
HOT-XXX
Jacoby, 1983
Probability correct
0.85
Identification
0.8
Recognition
0.75
0.7
0.65
0.6
0.55
0.5
no context
context
Study Task
generate
• Demonstrations of implicit memory
in normals (cont’d)
– Graf & Schacter (1987):
• Little interference with implicit
tasks
Word pairs studied (AB)
RI:
PI:
AB
AD
AD
AB
---
AB
AB
Control group learns CD
RI
PI
Ctl
Exp
Ctl
Exp
Cued recall
Fragment
.55
.40
.67
.45
Completion
.34
.32
.32
.35
THEORETICAL ACCOUNTS OF
IMPLICIT MEMORY
• The activation view (Graf & Mandler,
1987)
– IM as a subset of EM processes
• IM reflects activation of prior memories
• EM requires integration / elaboration
– Problems:
• Amnestics can learn new associations
• Priming can last for months
• The systems view (Tulving, 1985;
Schacter, 1987)
– IM based on procedural system, EM on
declarative system
• EM more advanced
• Explains neuroanatomic dissociations
– Problems:
• A system for every dissociation?
• Lack of consensus about criteria
• The processing view (Roediger,
Weldon & Challis, 1987)
– Transfer-appropriate memory tests
• IM : data-driven processing
• EM: conceptually-driven processing
– Dissociations can be TAP-based
(Blaxton, 1989)
“generate” (vs. read) gives better memory
for conceptually-driven tests
free recall (EM)
semantic cued recall (EM)
Jeopardy question-answers (IM)
and worse memory for data-driven tests
fragment completion (IM)
graphemically-cued recall (EM)
– Problems:
• Fuzzy bounds of processes
• Can become circular
• Doesn’t handle amnestic data well
THE PROCESS-DISSOCIATION
APPROACH (Jacoby, 1991)
• The problem of “process-impure
tests”
– Jacoby’s process-dissociation technique
– Assumes indendent concious (C) and
unconscious (U) contributions to memory
– To dissociate these:
two sets of items presented (e.g., some
read, some heard)
inclusion task: recall all
exclusion task: recall only heard items
p[R]|inclusion = p[C] + p[U] – p[U] x p[C]
= p[C] + p[U] x p[1-C]
p[R]|exclusion =
p[U] x p[1-C]
so: p[C] = p[R]|inclusion – p[R]|exclusion
then solve first equation for U:
U = p[R]|exclusion] / (1 – C)
• Applying Process Dissociation: Jacoby,
Toth & Yonelinas (1993)
study presentation
Read
Incl Excl
Heard
Incl
Excl
Full attn
.61
.36
.47
.34
Divided
.46
.46
.42
.46
Estimated contributions of C and U to
memory:
C(conscious) U(automatic)
Full attn
.25
.47
Divided
.00
.46
Controversies about independence and
other assumptions