Natasha Gandham

1. What are confabuloators’ memories made of? A study of subjective and objective measures of recollection in confabulation Natasha Gandham

2. 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

3. Introduction • 3 Goals of present study: • Extent to which subjective measures of recollection behave similarly to objective behavioural indicators of recollection • 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

4. 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)

5. 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)

6. 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

7. 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

8. 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

9. Results

10. 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?

11. 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