Confidence in Errors as a Possible Basis for Delusions in Schizophrenia

Abstract

In two previous studies, it was observed that schizophrenic patients display increased confidence in memory errors compared with controls. The patient group displayed an increased proportion of errors in their knowledge system, quantified as the percentage of high-confident responses that are errors. The latter phenomenon has been termed knowledge corruption and is put forward as a risk factor for the emergence of delusions. In the present study, knowledge corruption was analyzed separately for different aspects of memory errors. A source-monitoring task was used, for which participants (30 schizophrenic patients with past or current paranoid ideas and 15 healthy controls) were asked to provide associates for each of 20 prime words. Later, participants were required to recognize studied words among distractor words, judge the original source, and provide a confidence rating for the most recent decision. Schizophrenic patients displayed greater confidence in memory errors compared with controls. Knowledge corruption was observed to be significantly greater in schizophrenic patients relative to controls for false-positive and false-negative judgments. It is proposed that reliance on false knowledge represents a candidate mechanism for the emergence of fixed false beliefs (i.e., delusions).

Distinguishing familiarity-based from source-based memory performance in patients with schizophrenia

“…In addition, the reaction time associated with false alarms was actually faster than that seen in the controls. This latter result is particularly interesting, as it highly consistent with a body of evidence demonstrating enhanced confidence in errant responses (and reduced confidence in correct responses) in patients with schizophrenia (Moritz, Woodward et al 2003;Moritz, Woodward et al 2005;.…”

“…Several other studies under the source memory umbrella have tested the ability of patients to distinguish selfgenerated from examiner-generated information (internal vs. external) or to distinguish between words imagined versus actually said by the patient (internal vs. internal). This literature is also decidedly mixed, with at least seven previous papers failing to find a significant performance difference between patients with schizophrenia and control subjects (Harvey and Serper 1990;Morrison and Haddock 1997;Keefe, Arnold et al 1999;Moritz, Woodward et al 2005;Ragland, McCarthy et al 2006). Thus, after controlling for differences in simple recognition memory, several studies have not uncovered an additional deficit in source memory performance.…”

“…First, it appears that simple recognition memory is more impaired in patients with schizophrenia than previously appreciated (Pelletier, Achim et al 2005). In addition, a number of recent papers (Moritz, Woodward et al 2005;Ragland, McCarthy et al 2006;Weiss, Goff et al 2006), have failed to find a specific deficit in sourcebased memory in schizophrenia.…”

Memory and metamemory in schizophrenia: a liberal acceptance account of psychosis

“…In addition to diminished memory accuracy, which is mainly associated with depression and negative symptomatology (Brébion et al 2000), a number of metamemory dysfunctions have been described that relate to more qualitative aspects of recollection. Apart from poor vividness of recollection (Huron et al 1995 ;Danion et al 1999Danion et al , 2003, multiple studies have indicated that patients with schizophrenia display overconfidence in errors, while at the same time being less confident in correct responses (Moritz et al 2003(Moritz et al , 2005b. In a recent study this twofold response pattern, termed reduced 'confidence gap ', discriminated schizophrenia patients from both healthy and psychiatric controls, whereas indices of memory accuracy failed to yield significant differences between psychiatric groups .…”

False Reports from Patients with Frontotemporal Dementia: Delusions or Confabulations?

“…Another similarity between delusions and confabulations is an abnormal level of certainty for the false report [39]. Our patients continued to report their delusions or confabulations despite proof to the contrary.…”