A failure of conflict to modulate dual-stream processing may underlie the formation and maintenance of delusions

Eur Psychiatry. 2010 Mar;25(2):80-6. doi: 10.1016/j.eurpsy.2009.05.012. Epub 2009 Aug 21.


Background: Dual-stream information processing proposes that reasoning is composed of two interacting processes: a fast, intuitive system (Stream 1) and a slower, more logical process (Stream 2). In non-patient controls, divergence of these streams may result in the experience of conflict, modulating decision-making towards Stream 2, and initiating a more thorough examination of the available evidence. In delusional schizophrenia patients, a failure of conflict to modulate decision-making towards Stream 2 may reduce the influence of contradictory evidence, resulting in a failure to correct erroneous beliefs.

Method: Delusional schizophrenia patients and non-patient controls completed a deductive reasoning task requiring logical validity judgments of two-part conditional statements. Half of the statements were characterized by a conflict between logical validity (Stream 2) and content believability (Stream 1).

Results: Patients were significantly worse than controls in determining the logical validity of both conflict and non-conflict conditional statements. This between groups difference was significantly greater for the conflict condition.

Conclusions: The results are consistent with the hypothesis that delusional schizophrenia patients fail to use conflict to modulate towards Stream 2 when the two streams of reasoning arrive at incompatible judgments. This finding provides encouraging preliminary support for the Dual-Stream Modulation Failure model of delusion formation and maintenance.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Case-Control Studies
  • Cognition*
  • Conflict, Psychological*
  • Decision Making*
  • Delusions / psychology*
  • Emotions*
  • Female
  • Humans
  • Logic
  • Male
  • Middle Aged
  • Psychiatric Status Rating Scales
  • Psychological Tests
  • Schizophrenic Psychology*
  • Task Performance and Analysis