What are confabuloators’ memories made of? A study of subjective and objective

measures of recollection in confabulation

Natasha Gandham

Introduction

What are confabulators?› Have memories for events that

have not been actually experienced suggesting a vivid subjective experience of false memories

› Impairment of retrieval rather than encoding processes

Understanding nature of the subjective experience associated to memory retrieval in confabulators may help our understanding of the responsible mechanisms

Introduction

3 Goals of present study:

1) Extent to which subjective measures of recollection behave similarly to objective behavioural indicators of recollection

2) Extent to which subjective measures of recollection are affected by variables that are known to affect objective measures of recollection

3) Identify type of information that triggers remembering states in confabulators compared to the other participant groups

Introduction

Recollection is distinguished from familiarity› Recollection: retrieval of contextual details› Familiarity: global strength of the memory

trace without additional qualitative information Individuals are thought to be able to

differentiate between their subjective experience of recollection versus familiarity› Recollect some aspects of recognized item (i.e.

R response)› Item is merely familiar (K response)

Experimental Task

Subjects› 12 subjects with brain damage

5 suffered from AcoA aneurysm, confabulators Mean age = 55 years (range 45-65), mean 9 years

education (range 8-13) 7 patients with frontal lobe lesions, non-

confabulators Mean age = 51.7 years (range 40-59), mean 8.5

years of education (range 5-13)

› 12 control subjects Mean age = 53 years (range 44-65), mean 9.3 years

of education (range 8-13)

Experimental Task

Materials› 80 medium frequency words, between 4-8

letters long randomly assigned into 2 sets of 40

› One set was studied and the other set was used as distracters

› Remember (R)/Know (K) paradigm

Experimental Task

Procedure› Subjects told to memorize words as fast as they

could for a later memory test Confabulators and non-confabulators were tested

immediately after study phase and control subjects tested after 10 min. interval

› Subjects asked to indicate whether each word was “old” or “new”

› “old” Indicate whether they remembered or knew the word Indicate R/K responses (what they actually

remembered about item presentation at study) 2 raters, blind experiment

Experimental Task

Procedure› Rater’s classified subjects’ reports as…

Intra-list (IL): list context, sensory characteristics of word, item-specific images generated at study

Extra-list (EL): reflect thoughts/encoding operations made at study

Self-referent (SE): personal memory from everyday life

F: sense of familiarity, but no qualitative feature

Results

Discussion

Confabulators produce higher rates of SE responses than other participants› “self-serving” biases in memory reports of

confabulators› Deficits in processing of self-related

information?› Ventro-medial prefrontal cortex processes

information regarding the self and is often damaged in confabulating patients

› Future experiments: Is this a cause or symptom?

My Opinion

Strengths› Participants were well-matched on a variety of

indices › R/K paradigm has proven reliability and validity› Ensured participants understood the R/K

distinction› Blind experiment› High inter-rater reliability (93-98%)

Weakness› Failed to test 2 non-confabulating patients (CC

and GN) on the confabulation battery