Search

Parrott and Koralus argue that a particular cognitive factor – “impaired endogenous question raising” – offers a parsimonious account of three delusion-related phenomena: (1) the development of the Capgras delusion; (2) evidence that patients with schizophrenia outperform healthy control participants on a conditional reasoning task; and (3) evidence that deluded individuals “jump to conclusions”. In this response, I assess these claims, and raise my own questions about the “erotetic” theory of delusional thinking. [ABSTRACT FROM AUTHOR]

Introduction: That delusional and delusion-prone individuals "jump to conclusions" on probabilistic reasoning tasks is a key finding in cognitive neuropsychiatry. Here we focused on a less frequently investigated aspect of "jumping to conclusions" (JTC): certainty judgments. We incorporated rigorous procedures from experimental economics to eliminate potential confounds of miscomprehension and motivation and systematically investigated the effect of incentives on task performance. Methods: Low- and high-delusion-prone participants (n = 109) completed a series of computerised trials; on each trial, they were shown a black or a white fish, caught from one of the two lakes containing fish of both colours in complementary ratios. In the betting condition, participants were given £4 to distribute over the two lakes as they wished; in the control condition, participants simply provided an estimate of how probable each lake was. Deviations from Bayesian probabilities were investigated. Results: Whereas high-delusion-prone participants in both the control and betting conditions underestimated the Bayesian probabilities (i.e. were conservative), low- delusion-prone participants in the control condition underestimated but those in the betting condition provided accurate estimates. In the control condition, there was a trend for high-delusion-prone participants to give higher estimates than low-dclusion- prone participants, which is consistent with previous reports of "jumping to conclusions" in delusion-prone participants. However, our findings in the betting condition, where high-delusion-prone participants provided lower estimates than low- delusion-prone participants (who were accurate), are inconsistent with the jumping-to- conclusions effect in both a relative and an absolute sense. Conclusions: Our findings highlight the key role of task incentives and underscore the importance of comparing the responses of delusion-prone participants to an objective rational standard as well as to the responses of non-delusion-prone participants. [ABSTRACT FROM AUTHOR]

False claims are a key feature of confabulation, delusion, and anosognosia. In this paper we consider the role of motivational factors in such claims. We review motivational accounts of each symptom and consider the evidence adduced in support of these accounts. In our view the evidence is strongly suggestive of a role for motivational factors in each domain. Before concluding, we widen the focus by outlining a tentative general taxonomy of false claims, including false claims that occur in clinical settings as well as more garden-variety false claims, and incorporating both motivational and nonmotivational approaches to explaining such claims. [ABSTRACT FROM AUTHOR]

Abstract: The impact of our desires and preferences upon our ordinary, everyday beliefs is well-documented [. How we know what isn’t so: The fallibility of human reason in everyday life. New York: The Free Press.]. The influence of such motivational factors on delusions, which are instances of pathological misbelief, has tended however to be neglected by certain prevailing models of delusion formation and maintenance. This paper explores a distinction between two general classes of theoretical explanation for delusions; the motivational and the deficit. Motivational approaches view delusions as extreme instances of self-deception; as defensive attempts to relieve pain and distress. Deficit approaches, in contrast, view delusions as the consequence of defects in the normal functioning of belief mechanisms, underpinned by neuroanatomical or neurophysiological abnormalities. It is argued that although there are good reasons to be sceptical of motivational theories (particularly in their more floridly psychodynamic manifestations), recent experiments confirm that motives are important causal forces where delusions are concerned. It is therefore concluded that the most comprehensive account of delusions will involve a theoretical unification of both motivational and deficit approaches. [Copyright &y& Elsevier]

Introduction. The present study was designed to replicate and extend the findings of Bentall and Swarbrick (2003). It was hypothesised that patients with a history of persecutory delusions would display higher need for closure and a more extreme jumping to conclusions bias than healthy control participants. Methods. Twenty-two patients with a history of persecutory delusions and nineteen healthy control participants were administered a probabilistic reasoning task, along with self-report measures of depression and need for closure. Results. The clinical group scored higher on need for closure than the controls, but showed no greater tendency to jump to conclusions. No relationship was found between need for closure and a jumping to conclusions bias. Conclusions. The results confirm an association between persecutory delusions and need for closure, yet suggest that persecutory delusions in an outpatient sample can be seen in the absence of a jumping to conclusions bias. [ABSTRACT FROM AUTHOR]

Two different modes of theorising about delusions are explored. On the one hand is the motivational approach, which regards delusions as serving a defensive, palliative, even potentially adaptive function. On the other, is the cognitive deficit approach, which conceptualises delusions as explicitly pathological, involving abnormalities in ordinary cognitive processes. The former approach, prominently exemplified by the psychoanalytic tradition, was predominant historically, but has been challenged in recent years by the latter. Some grievances against psychoanalytic theory are briefly discussed, and it is argued that although the reasons for psychoanalysis falling into scientific disrepute are partly justified, the psychodynamic notion that motivation has access to the mechanisms of belief formation is of potentially crucial theoretical utility. A variety of possible syntheses of the two theoretical modes are therefore explored, in the belief that the most comprehensive account of delusions will involve a theoretical unification of both styles of explanation. Along the way, an attempt is made to locate the notions delusion, defence, and self‐deception in a shared theoretical space. [ABSTRACT FROM AUTHOR]