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 GAZETTE PLANKTON BACHELOR IDEOLOGY RUFFIAN BROCCOLI LITHIUM THEOREM NOCTURNE ALMANAC GRANARY QUARTET BEHAVIOR LAGGARD SILICON CLARINET MYSTERY PENDULUM 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

S I _ _ C _ N _ D E O _ O _ _ _ U F F A _ _ B _ _ C C _ _ I _ _ _ N K _ O N N O _ _ _ _ N E A L _ _ N _ _ _ A Z _ _ T E _ _ T H _ U M B E _ _ V I _ _ _ U _ R _ E T G _ A _ _ R Y _ L _ R _ _ E T _ I G R _ _ N E _ G _ O _ T I _ L _ G _ _ R D _ E _ D _ L _ M _ H _ O _ E M B A _ _ E _ O R _ Y S _ _ R Y

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 19 th 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) recognfragment ID Amnestics 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 contextcontext generate XXX-COLDHOT-COLD HOT-XXX

Demonstrations of implicit memory in normals (cont’d) –Graf & Schacter (1987): Little interference with implicit tasks Word pairs studied (AB) RI:ABAD--AB PI:ADAB--AB Control group learns CD RI PI CtlExpCtlExp Cued recall Fragment Completion

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 ReadHeard Incl Excl Incl Excl Full attn Divided Estimated contributions of C and U to memory: C(conscious) U(automatic) Full attn Divided Controversies about independence and other assumptions