Comprehension, encoding, and monitoring in the production of confabulation in memory: a study with schizophrenic patients.
BACKGROUND
The aim of the present study was to test the hypotheses proposed by Nathaniel-James and collaborators (Nathaniel-James & Frith, 1996; Nathaniel-James, Foong, & Frith, 1996) to account for the cognitive deficits involved in the production of confabulations in schizophrenic patients: impairments in comprehension, memory encoding, and memory monitoring.


METHODS
Five patients were investigated in this multiple single-case study. Comprehension abilities were investigated in several tests in which a memory bias was avoided. The encoding deficit hypothesis was tested by manipulating cues at encoding and/or retrieval. "Memory monitoring" abilities were examined in two tasks: the Hayling test for all patients and an AB-AC word pairs learning task for two patients.


RESULTS
Four of the patients produced an abnormal level of confabulations in story and fable learning tests. All patients exhibited encoding deficits and specific comprehension difficulties. However, some demonstrated preserved memory monitoring abilities. Across different tests, it was observed that the more the confabulations occurred, the more severe were the comprehension difficulties.


CONCLUSIONS
The results are in favour of the hypothesis that verbal comprehension difficulties lead to the production of confabulation. They are inconsistent with the idea that memory monitoring impairment is necessarily involved.
Université Libre de Bruxelles, Research Unit in Cognitive Neuroscience, Belgium. sasdab@ulb.ac.be
Saskia
S
Dab
José
J
Morais
Chris
C
Frith