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