False Memory Phenomena James Raftery Psy/Orf 322 Spring 2004

Can we trust our memory? Victim Testimony “Repressed” abuse in therapy

What is the issue? Memory as constructive process Coherent memory –Bits of actual memory –Context –Repetition

False Memory Experiment Quantitative Measurements –Inherent difficulties Simple measurable tasks = little error Reproductive VS Reconstructive? –Henry Roediger/Kathleen McDermott’s experiments

Method Lists of Words “Critical Lure” Bidirectional associations 42-item lists read aloud Subject wrote down as many as could be remembered without ‘guessing’ At the end asked to judge if they had seen certain words on the list

Experiment Results Critical Lure 55% (higher than in exp1) Recall Condition Enhanced Effect Had physical memories of the lures

Implications False Memory is quantifiable All memory is constructive, not reproductive – even rote recall Effects were substantial in a lab setting, in a traumatic situation effects are likely even more powerful

Parallel Distributed Process Experiences are represented in the mind by their several aspects (within descriptive categories) Different experiences share aspects Connections between two aspects are strengthened when both are activated

Dynamic Nature Of PDP Memory Later events alter connections When one aspect is used as trigger for memory, it activates all others that it is connected with A lack of a strong connection will allow for several weak connections to be asserted, giving rise to confusion or generalization

False Memory Simulator Purpose: To replicate Roediger and McDermott’s results with a neural network All words in list related to each other Primarily activate themselves, but to some extent activate similar words If a word (critical lure) reaches a certain threshold of excitement it will register as having been on the list

Implementation Each word has a weight with all other words on list –Weights stored in a matrix –Strong weight associated between a word and itself –Vector of input words put through matrix determines net excitation of all words –If a specific threshold is reached, the network will output it as a recalled word