IMPLICIT MEMORY: A

1
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

2
Anecdotal Examples of Implicit Memory

• Cases of unconscious plagiarism
• George Harrison and the Chiffons
• Freuds 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)

3
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)

4
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)
• 1970s
• 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
5

• 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 context generate
• XXX-COLD HOT-COLD HOT-XXX

6

• Demonstrations of implicit memory in normals
  (contd)
• Graf Schacter (1987)
• Little interference with implicit tasks

Word pairs studied (AB) RI AB AD -- AB
PI AD AB -- AB Control group learns CD
RI PI Ctl Exp Ctl Exp Cued
recall .55 .40 .67 .45 Fragment Completion .34 .3
2 .32 .35
7
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

8

• 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
• Doesnt handle amnestic data well

9
THE PROCESS-DISSOCIATION APPROACH (Jacoby, 1991)

• The problem of process-impure tests
• Jacobys process-dissociation technique
• Assumes indendent concious (C) and unconscious
  (U) contributions to memory
• To dissociate thesetwo sets of items presented
  (e.g., some read, some heard)inclusion task
  recall allexclusion task recall only heard
  itemspcorrinclusion pC pU pU x
  pC pC pU x
  p1-Cpcorrexclusion pU x
  p1-Cso pC inclusion exclusion then
  solve first equation for U

10

• Applying Process Dissociation Jacoby, Toth
  Yonelinas (1993)

study presentation Read Heard Incl
Excl 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