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IMPLICIT MEMORY: A “HIDDEN WORLD?”

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

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IMPLICIT MEMORY: A “HIDDEN WORLD?”

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  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 • 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)

  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) • 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

  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 (cont’d) • 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 .32 .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 testsfree recall (EM) semantic cued recall (EM) Jeopardy question-answers (IM)and worse memory for data-driven testsfragment completion (IM) graphemically-cued recall (EM) • Problems: • Fuzzy bounds of processes • Can become circular • Doesn’t handle amnestic data well

  9. 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 allexclusion task: recall only heard itemsp[corr]inclusion = p[C] + p[U] – p[U] x p[C] = p[C] + p[U] x p[1-C]p[corr]exclusion = p[U] x p[1-C]so: p[C] = inclusion – exclusionthen solve first equation for U

  10. 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 • Applying Process Dissociation: Jacoby, Toth & Yonelinas (1993)

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