Exploring rationality in schizophrenia

Abstract

BackgroundEmpirical studies of rationality (syllogisms) in patients with schizophrenia have obtained different results. One study found that patients reason more logically if the syllogism is presented through an unusual content.AimsTo explore syllogism-based rationality in schizophrenia.MethodThirty-eight first-admitted patients with schizophrenia and 38 healthy controls solved 29 syllogisms that varied in presentation content (ordinary v. unusual) and validity (valid v. invalid). Statistical tests were made of unadjusted and adjusted group differences in models adjusting for intelligence and neuropsychological test performance.ResultsControls outperformed patients on all syllogism types, but the difference between the two groups was only significant for valid syllogisms presented with unusual content. However, when adjusting for intelligence and neuropsychological test performance, all group differences became non-significant.ConclusionsWhen taking intelligence and neuropsychological performance into account, patients with schizophrenia and controls perform similarly on syllogism tests of rationality.Declaration of interestNone.Copyright and usage© The Royal College of Psychiatrists 2015. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) licence.

Delusions beyond beliefs: a critical overview of diagnostic, aetiological, and therapeutic schizophrenia research from a clinical-phenomenological perspective

“…First, despite initial enthusiasm, differences in formal syllogisticdeductive reasoning have been shown to be nonsignificant in their association with delusions when other variables (eg, IQ and neuropsychological perfor mance) are controlled for. [95][96][97] Moreover, on measures of socalled pure theoretical reasoning abstracted from pragmatic significance and practical rationality, patients have sometimes even been found to outperform controls 98 (yet see Revsbech and colleagues 99 ). More problematic still for this line of approach is that delusions tend to be highly circumscribed, revolving around specific themes, 100 which is difficult to align with the essentially more global nature of reasoning impairments.…”

Formalising theories of human decision-making for agent-based modelling of social-ecological systems: practical lessons learned and ways forward

“…Furthermore, some theories can instead be characterised as broader meta-theories with many different aspects that must potentially be considered. A well-known example is bounded rationality, which covers many concepts that can potentially be included in a model (e.g., the amount of information considered by the agents, processing capacity, errors in perception, Gigerenzer and Goldstein, 1996;Kahneman, 2003). While the modelling context influences theory selection, modellers will hardly find exactly one specific theory to match their problem.…”

“…The behaviour and the available behavioural options to be included in the model may hint at certain theories. For example, modelling everyday decisions advocates theories on habits and how to overcome them or the use of fast and frugal heuristics (Gigerenzer & Goldstein, 1996). The latter suggests that decision problems are solved with simple rules focusing on only one aspect of the decision problem.…”

Deficits in Analytic and Common-Sense Reasoning in Schizophrenia

“…In a preliminary study with small sample size, Owen et al (2007) surprisingly found that patients with schizophrenia were more accurate than healthy controls on valid syllogisms presented with unusual content or invalid syllogisms presented with ordinary content. In a second study including 38 patients with schizophrenia and healthy controls, controls tended to outperform patients on all syllogism types, but the difference between the two groups was significant only for valid syllogisms presented with unusual content (Revsbech et al, 2015). In both of these studies investigating syllogisms in patients with schizophrenia and healthy controls, common sense significantly interfered with analytical processing and led to significant belief bias when the conclusions are ordinary but not valid (Owen et al, 2007; Revsbech et al, 2015).…”

“…Available previous research with patients with schizophrenia has shown impaired performance in syllogism tests of rationality (Goel et al, 2004; Mujica-Parodi et al, 2000). It is also important to note that validity judgments about syllogisms might be influenced by the nature of their content (ordinary versus unusual) (Evans, 2002; Revsbech et al, 2015). Thus if the content of stimuli in a syllogism test is ordinary and common sense, more people will give a “true” response to a logically incorrect conclusion.…”