INTERFERENCE IN EPISODIC MEMORY Causes of forgetting –Interference versus decay –McGeoch (1932) & the triumph of interference –Forgetting and the issue of permanence Associative Interference in PAL –The Paired-Associate Learning task –What is learned? Response learning Stimulus differentiation Associative hook-up Item- and list-level knowledge –Retroactive and Proactive interference The RI and PI designs Effects of number and strength of competing responses Effects of retention interval on RI and PI Effects of type of test

Classic PAL interference Designs DOG-ROCK DOG-SKYPLAN-ROCKPLAN-SKY AB ACCB CD DOG:____? DOG: stone sky rock

MECHANISMS OF ASSOCIATIVE INTERFERENCE The main issue: is interference passive (e.g., occlusion), or active (e.g., retrieval inhibition)? Ineffective routes –Response competition / occlusion Other associations to cue occlude AB Is it eliminated in recognition tests? Is it eliminated in MMFR tests? –Unlearning (for RI designs) Learning AD weakens AB association Analogy to extinction in conditioning Mixed evidence in “recovery” Ineffective cues –Varied Stimulus Encoding Learning AD forces differential A encoding Analogy to encoding specificity effects Evidence against its role in PAL –Williams & Underwood (1970): XRM cue, X is best for both B and D

List-wide interference –Response-set suppression (Postman, Stark & Frasier, 1968) Inference in the AB,CD paradigm Independence of item-level recall in AB,AD paradigm Is it “suppression” or context-change? Interference in other episodic tasks –Part-set cuing (Slamecka 1968) –Directed forgetting (Bjork et al. 1968) The DF paradigm e.g., Geiselman, Bjork & Fishman ’83) 48 nouns: 1 st half mixed “learn” & “judge” Cue to forget or remember 1 st half LearnJudge Final recall: F R F R 1 st half nd half

Explanations of Directed forgetting –Bjork: inhibition / suppression of Forget words (singly or as sublist) But: no DF effect in recognition –Sahakyan & Kelley (02): “forget” cue as context shift E1: context-change (“imagine you’re invisible”) No changeChange Final recall: F R F R 1 st half nd half E2: Reinstate initial context at test ReinstatedNot Reinstated Final recall: F R+C R F R+C R 1 st half: nd half:

Inhibition in other domains? –Negative priming effects in naming (Tipper, 85) –Inhibition of return in spatial attention (Posner& Nissen, 1980) –Retrieval effort and inhibition in semantic memory (Dagenbach, 1990) Ss learn meanings of obscure words –E.g., accipiter: hawk As primes for related words, these words –Facilitate lexical decision if recalled –But inhibit lexical decision if not (?!) –Suppression of subordinate homograph meanings in long-SOA priming (Burgess & Simpson 1988) Prime: RING Target: BELL Facilitates lexical decision at 35 ms SOA Slows lexical decision at 750 ms SOA –Inhibition of literal meaning response after figurative use (Glucksberg, 1982) My lawyer is a shark / sharks have skin –Suppression of referents in sentence comprehension (Gernsbacher, 1982) Ann dropped the box. It / She….

Retrieval-Induced Forgetting –(Anderson, Bjork & Bjork 1994) Study: sets of of category-instance pairs FRUIT-orange; FRUIT-apple, etc (n=6)\ TOOL-drill, TOOL-hammer, etc. Cued retrieval practice on half of some categories: FRUIT – or____ Cued-recall test of all pairs RP+ RP- No RP “good” e.g.’s “weak” e.g.’s

Is it Inhibition? –Anderson et al. (94): high and low taxonomic frequency: Practiced Items nonpracticed items High Low RP+ RP-RP+ RP- High Low –Anderson & Spellman (95): cross-cuing paradigm Some items in one category could be items in another (TOMATO as “RED” or “FOOD” Results show “cue independent inhibition:”

Results of Anderson & Spellman, 95’s independent-probe study:

Failure of cross-cue inhibition in PAL: Fischler & Wood (1985) Fist phase: Learn AB, DB pairs RI Phase: Learn AC for half the list pairs Test phase: cued with A, B shows strong interference from AC cued with D, B shows no interference from AC E2: Precued (100 ms) with (A)D, All B responses are slowed

Recent developments (SEPA report) –Inhibition in the “no think” paradigm (Anderson, 2005) Ss learn paired-associates Retrieval or “no think” practice with exposure to some stimulus words Within-list inhibition for “no think” pairs –So: item-specific directed forgetting? “no think” stimuli asssociated with increased DLPFC, decreased hippocampal (contralateral?) activity Degree of activity correlated with size of inhibitory effect –Extensions of RP effects to eyewitness memory, semantic memory, text, etc. –Some failures to show cue independence, or “strength independence” –Issue of degree of “output interference” as cause of RP- inhibition