Delusion proneness and 'jumping to conclusions': relative and absolute effects

A neural code supporting prospective probabilistic reasoning for instrumental information demand in humans

When making adaptive decisions, we actively demand information, but relatively little is known about the mechanisms of active information gathering. An open question is how the brain prospectively estimates the information gains that are expected to accrue from various sources by integrating simpler quantities of prior certainty and the reliability (diagnosticity) of a source. We examine this question using fMRI in a task in which people placed bids to obtain information in conditions that varied independently in the rewards, decision uncertainty, and information diagnosticity. We show that, consistent with value of information theory, the participants' bids are sensitive to prior certainty (the certainty about the correct choice before gathering information) and expected posterior certainty (the certainty expected after gathering information). Expected posterior certainty is decoded from multivoxel activation patterns in the posterior parietal and extrastriate cortices. This representation is independent of instrumental rewards and spatially overlaps with distinct representations of prior certainty and expected information gains. The findings suggest that the posterior parietal and extrastriate cortices are candidates for mediating the prospection of posterior probabilities as a key step to anticipating information gains during active gathering of instrumental information.

A Bayesian model of the jumping-to-conclusions bias and its relationship to psychopathology

The mechanisms by which delusion and anxiety affect the tendency to make hasty decisions (Jumping-to-Conclusions bias) remain unclear. This paper proposes a Bayesian computational model that explores the assignment of evidence weights as a potential explanation of the Jumping-to-Conclusions bias using the Beads Task. We also investigate the Beads Task as a repeated measure by varying the key aspects of the paradigm. The Bayesian model estimations from two online studies showed that higher delusional ideation promoted reduced belief updating but the impact of general and social anxiety on evidence weighting was inconsistent. The altered evidence weighting as a result of a psychopathological trait appeared insufficient in contributing to the Jumping-to-Conclusions bias. Variations in Beads Task aspects significantly affected subjective certainty at the point of decisions but not the number of draws to decisions. Repetitions of the Beads Task are feasible if one assesses the Jumping-to-Conclusions bias using number of draws to decisions.

The parieto-occipital cortex is a candidate neural substrate for the human ability to approximate Bayesian inference

Adaptive decision-making often requires one to infer unobservable states based on incomplete information. Bayesian logic prescribes that individuals should do so by estimating the posterior probability by integrating the prior probability with new information, but the neural basis of this integration is incompletely understood. We record fMRI during a task in which participants infer the posterior probability of a hidden state while we independently modulate the prior probability and likelihood of evidence regarding the state; the task incentivizes participants to make accurate inferences and dissociates expected value from posterior probability. Here we show that activation in a region of left parieto-occipital cortex independently tracks the subjective posterior probability, combining its subcomponents of prior probability and evidence likelihood, and reflecting the individual participants' systematic deviations from objective probabilities. The parieto-occipital cortex is thus a candidate neural substrate for humans' ability to approximate Bayesian inference by integrating prior beliefs with new information.

A Distinct Neural Code Supports Prospection of Future Probabilities During Instrumental Information-Seeking

To make adaptive decisions, we must actively demand information, but relatively little is known about the mechanisms of active information gathering. An open question is how the brain estimates expected information gains (EIG) when comparing the current decision uncertainty with the uncertainty that is expected after gathering information. We examined this question using fMRI in a task in which people placed bids to obtain information in conditions that varied independently by prior decision uncertainty, information diagnosticity, and the penalty for an erroneous choice. Consistent with value of information theory, bids were sensitive to EIG and its components of prior certainty and expected posterior certainty. Expected posterior certainty was decoded above chance from multivoxel activation patterns in the posterior parietal and extrastriate cortices. This representation was independent of instrumental rewards and overlapped with distinct representations of EIG and prior certainty. Thus, posterior parietal and extrastriate cortices are candidates for mediating the prospection of posterior probabilities as a key step to estimate EIG during active information gathering.

Responses to Raven matrices: Governed by visual complexity and centrality

Raven matrices are widely considered a pure test of cognitive abilities. Previous research has examined the extent to which cognitive strategies are predictive of the number of correct responses to Raven items. This study examined whether response times can be explained directly from the centrality and visual complexity of the matrix cells (edge density and perceived complexity). A total of 159 participants completed a 12-item version of the Raven Advanced Progressive Matrices. In addition to item number (an index of item difficulty), the findings demonstrated a positive correlation between the visual complexity of Raven items and both the mean response time and the number of fixations on the matrix (a strong correlate of response time). Moreover, more centrally placed cells as well as more complex cells received more fixations. It is concluded that response times on Raven matrices are impacted by low-level stimulus attributes, namely, visual complexity and eccentricity.

Associations between acceptance of the implausible bias, theory of mind and delusions in first-episode psychosis patients; A longitudinal study

Multiple different cognitive biases, among them the liberal acceptance (LA) bias, have been suggested to contribute to reality distortion in psychotic disorders. Earlier studies have been cross-sectional and considered a limited set of cognitive correlates of psychosis, thus the relationship between LA bias and psychosis remains poorly known. We studied a similar bias (acceptance of the implausible (AOI)) in 62 first-episode psychosis (FEP) patients and 62 control subjects, who watched movie scenes with varying degrees of realism and were asked to evaluate the probability of these events occurring in real life. We assessed theory of mind (ToM) performance using the Hinting task and delusion severity using Brief Psychiatric Rating Scale item 11. We correlated the magnitude of AOI with the severity of delusions and performance in the ToM task. Furthermore, we used 1-year follow-up data from 40 FEP patients and 40 control subjects to disentangle state vs trait-like characteristics of AOI. At baseline FEP patients expressed more AOI than control subjects, and the magnitude of AOI correlated positively with the severity of delusions and negatively with ToM performance. At the one-year follow-up, when most patients were in remission, patients still displayed increased AOI, which no longer correlated with delusions. These findings support the notion that the AOI bias could represent a trait rather than a state feature and support further studies to test the hypothesis that it could be one of the causal factors of psychotic disorders, possibly associated with ToM.

Antivax attitude in the general population along the autism-schizophrenia continuum and the impact of socio-demographic factors

Introduction

One of the most important inventions in human history is vaccines. However, to date a consistent amount of people exhibit a hesitant approach toward them and mixed results have emerged in the attempt to characterize which factors may play a role in predicting such negative attitude. Here, we aimed at investigating how the individual scoring along the autism-schizophrenic continuum component and socio-cultural factors contribute toward vaccination attitudes in the general population.

Methods

To test whether individual position along the autism-schizophrenic continuum could predict vaccine attitude, we used principal component analysis (PCA) to extract the component showing diametric loading between the Schizotypal Personality Questionnaire (SPQ) and Autistic Quotient (AQ) subscales. Then, we performed a series of multiple linear regression analyses to understand the relation between the ASD-SSD continuum component and Vax scores. We also included socio-demographic factors (i.e., gender, education level, and age) as predictors.

Results

Multiple regression analysis revealed that the closer the individual lied on the positive schizotypal pole, the higher was their negative attitude toward vaccines. A diametric, more favorable disposition was found for individuals closer to the autistic end of the continuum. Furthermore, we reported that among the socio-cultural factors, only age can be considered a significant predictor of vaccination attitudes, with younger participants showing a more positive attitudes toward vaccination, while the level of education is an important protective factor in mitigating the negative impact that the proximity to the SSD pole and age play against vaccination disposition.

Discussion

These findings are relevant to improve targeted public health interventions, highlighting the crucial role of demographic, psychological, and social correlates in predicting anti-vax beliefs, which have the devasting potential to increase the spread of infectious disease.

Bayesian reasoning with emotional material in patients with schizophrenia

Delusions are one of the most classical symptoms described in schizophrenia. However, despite delusions are often emotionally charged, they have been investigated using tasks involving non-affective material, such as the Beads task. In this study we compared 30 patients with schizophrenia experiencing delusions with 32 matched controls in their pattern of responses to two versions of the Beads task within a Bayesian framework. The two versions of the Beads task consisted of one emotional and one neutral, both with ratios of beads of 60:40 and 80:20, considered, respectively, as the “difficult” and “easy” variants of the task. Results indicate that patients showed a greater deviation from the normative model, especially in the 60:40 ratio, suggesting that more inaccurate probability estimations are more likely to occur under uncertainty conditions. Additionally, both patients and controls showed a greater deviation in the emotional version of the task, providing evidence of a reasoning bias modulated by the content of the stimuli. Finally, a positive correlation between patients’ deviation and delusional symptomatology was found. Impairments in the 60:40 ratio with emotional content was related to the amount of disruption in life caused by delusions. These results contribute to the understanding of how cognitive mechanisms interact with characteristics of the task (i.e., ambiguity and content) in the context of delusional thinking. These findings might be used to inform improved intervention programs in the domain of inferential reasoning.

Explaining human sampling rates across different decision domains

Undersampling biases are common in the optimal stopping literature, especially for economic full choice problems. Among these kinds of number-based studies, the moments of the distribution of values that generates the options (i.e., the generating distribution) seem to influence participants’ sampling rate. However, a recent study reported an oversampling bias on a different kind of optimal stopping task: where participants chose potential romantic partners from images of faces (Furl et al., 2019). The authors hypothesised that this oversampling bias might be specific to mate choice. We preregistered this hypothesis and so, here, we test whether sampling rates across different image-based decision-making domains a) reflect different over- or undersampling biases, or b) depend on the moments of the generating distributions (as shown for economic number-based tasks). In two studies (N = 208 and N = 96), we found evidence against the preregistered hypothesis. Participants oversampled to the same degree across domains (compared to a Bayesian ideal observer model), while their sampling rates depended on the generating distribution mean and skewness in a similar way as number-based paradigms. Moreover, optimality model sampling to some extent depended on the the skewness of the generating distribution in a similar way to participants. We conclude that oversampling is not instigated by the mate choice domain and that sampling rate in image-based paradigms, like number-based paradigms, depends on the generating distribution.

People with jumping to conclusions bias tend to make context-independent decisions rather than context-dependent decisions

Beads task (BT) uses a probabilistic reasoning paradigm and reveals jumping to conclusions (JTC) bias, the tendency to make premature judgments based on insufficient information (i.e., making fewer draws to decision-DTD). In this study, healthy participants (N = 207) were tested on the 80:20 and 60:40 color ratio versions of BT. We investigated associations of JTC bias with a set of cognitive bias problems and Cognitive Bias Task (CBT), a non-veridical (agent-centered) decision-making task that determines context-dependent and context-independent decision-making bias.Results showed that the converted CBT scores were negatively, and cognitive bias scores were positively correlated with JTC bias (DTD ≤ 2) on both versions of the BT. The CBT demonstrated to have satisfactory convergent and predictive validity for JTC bias. The findings suggest that people with JTC bias fail to solve cognitive bias problems and are more likely to make context-independent response selections than context-dependent response selections.

Of tinfoil hats and thinking caps: Reasoning is more strongly related to implausible than plausible conspiracy beliefs

People who strongly endorse conspiracy theories typically exhibit biases in domain-general reasoning. We describe an overfitting hypothesis, according to which (a) such theories overfit conspiracy-related data at the expense of wider generalisability, and (b) reasoning biases reflect, at least in part, the need to reduce the resulting dissonance between the conspiracy theory and wider data. This hypothesis implies that reasoning biases should be more closely associated with belief in implausible conspiracy theories (e.g., the moon landing was faked) than with more plausible ones (e.g., the Russian Federation orchestrated the attack on Sergei Skripal). In two pre-registered studies, we found that endorsement of implausible conspiracy theories, but not plausible ones, was associated with reduced information sampling in an information-foraging task and with less reflective reasoning. Thus, the relationship between belief in conspiracy theories and reasoning is not homogeneous, and reasoning is not linked specifically to the "conspiracy" aspect of conspiracy theories. Instead, it may reflect an adaptive response to the tension between implausible theories and other beliefs and data.

The tendency to stop collecting information is linked to illusions of causality

Previous research proposed that cognitive biases contribute to produce and maintain the symptoms exhibited by deluded patients. Specifically, the tendency to jump to conclusions (i.e., to stop collecting evidence soon before making a decision) has been claimed to contribute to delusion formation. Additionally, deluded patients show an abnormal understanding of cause-effect relationships, often leading to causal illusions (i.e., the belief that two events are causally connected, when they are not). Both types of bias appear in psychotic disorders, but also in healthy individuals. In two studies, we test the hypothesis that the two biases (jumping to conclusions and causal illusions) appear in the general population and correlate with each other. The rationale is based on current theories of associative learning that explain causal illusions as the result of a learning bias that tends to wear off as additional information is incorporated. We propose that participants with higher tendency to jump to conclusions will stop collecting information sooner in a causal learning study than those participants with lower tendency to jump to conclusions, which means that the former will not reach the learning asymptote, leading to biased judgments. The studies provide evidence in favour that the two biases are correlated but suggest that the proposed mechanism is not responsible for this association.

Problems in measuring the JTC-bias in patients with psychotic disorders with the fish task: a secondary analysis of a baseline assessment of a randomized controlled trial

BACKGROUND

The jumping to conclusions bias (JTC) is considered to be an important causal factor in theoretical models for the formation and maintenance of delusions. However, recent meta-analytic findings show a rather equivocal pattern of results regarding associations between JTC and delusions. Thus, the present study aims to investigate in a large sample whether the JTC-bias is more pronounced in patients with psychotic disorders in comparison to controls and whether the JTC bias is associated with a more severe delusional conviction, persecutory delusions, and positive symptoms in general.

METHODS

Patients with psychotic disorders (n = 300) enrolled in a therapy trial and healthy controls (n = 51) conducted a variant of the beads task (fish task) as a measure for the JTC-bias at the start of the trial. Further, clinical interviews were used to assess patients' delusional severity and delusional conviction.

RESULTS

There were no statistically significant differences between patients with psychotic disorders (with 53% displaying the JTC-bias) and controls (41%). Furthermore, there were no statistically significant correlations between JTC measures and persecutory delusions, delusional conviction, and positive symptoms.

CONCLUSIONS

We found no differences in JTC between patients with psychotic disorders and healthy controls, which is in part in line with meta-analytic findings using a wide range of JTC task variants. Interestingly, patients with psychotic disorders displayed JTC rates commonly found in the literature, while healthy control subjects showed an unexpectedly high level of JTC. The task variant we used in the present study (fish task) is discussed as a potential reason for our results, as it may induce a more deliberative reasoning style in controls as compared to the traditional beads task. Furthermore, possible implications for the measurement of the JTC-bias, in general, are discussed.

TRIAL REGISTRATION

ISRCTN29242879 ( isrctn.com ), date of registration: April 12th 2006, retrospectively registered.

Jumping to conclusions in the less-delusion-prone? Preliminary evidence from a more reliable beads task

BACKGROUND AND OBJECTIVES

Several meta-analyses have shown that people with psychosis tend to gather less information (i.e., they make fewer draws to decision, or DTD) on the beads task than healthy controls. A single meta-analysis has also found a small negative association between delusion-proneness and DTD in healthy samples, but with considerable heterogeneity.

METHODS

We used the new and more reliable "distractor sequences" beads task to clarify the nature of the relationship between delusion-proneness and DTD in a healthy sample. Healthy participants (N = 203) completed the distractor sequences beads task and the Peters Delusions Inventory (PDI), which measures delusion-proneness.

RESULTS

PDI and DTD were positively correlated, and those who jumped to conclusions (DTD ≤ 2) had lower PDI than those who did not. Comparing PDI quartiles on DTD provided some evidence the positive association did not extend to the highest PDI quartile. We found that DTD and delusion-proneness were positively related in our non-clinical sample, which was unexpected.

LIMITATIONS

Results need replication with a clinical sample.

CONCLUSIONS

Considering the well-established association between the JTC bias and clinical delusions, the current finding may reflect a relationship that differs between non-clinical and clinically significant delusional groups, or one which reverses sign at some level of delusion-proneness.

The Effect of Transcutaneous Auricular Vagal Nerve Stimulation (taVNS) on P3 Event-Related Potentials during a Bayesian Oddball Task

Transcutaneous auricular Vagal Nerve Stimulation (taVNS) is a non-invasive brain stimulation technique associated with possible modulation of norepinephrinergic (NE) activity. NE is suspected to contribute to generation of the P3 event-related potential. Recent evidence has produced equivocal evidence whether taVNS influences the P3 in healthy individuals during oddball tasks. We examined the effect of taVNS on P3 amplitudes using a novel visual Bayesian oddball task, which presented 200 sequences of three stimuli. The three consecutive stimuli in each sequence are labelled Draw 1, Draw 2 and Draw 3. In total, 47 Subjects completed this visual Bayesian oddball task under randomised sham and active taVNS stimulation in parallel with an electroencephalographic (EEG) recording. We conducted exploratory analyses of the effect of taVNS on P3 amplitudes separately for Draws. We found typical oddball effects on P3 amplitudes at Draws 1 and 2, but not Draw 3. At Draw 2, the oddball effect was enhanced during active compared to sham taVNS stimulation. These data provide evidence that taVNS influences parietal P3 amplitudes under specific circumstances. Only P3 amplitudes at Draw 2 were affected, which may relate to closure of Bayesian inference after Draw 2. Our findings seemingly support previously reported links between taVNS and the NE system.

Risky decision-making and delusion proneness: An initial examination

Delusion proneness is an individual-differences characteristic, existing on a continuum from no delusional thoughts to a diagnosis of schizophrenia. Previous research found individuals high in delusion proneness request less information to make decisions, potentially making a decision without sufficient information (jumping to conclusions). The present study examined risky decision-making as a function of delusion proneness. Participants (n = 102) completed the Peters Delusions Inventory to assess delusion proneness, and the Iowa Gambling Task (IGT) and Game of Dice Task (GDT) to assess risky decision-making. Although no significant results emerged on the GDT, those scoring higher in delusion proneness decided more advantageously on the IGT than those scoring lower in delusion proneness. Exploratory analyses indicated no significant relationship between gender and task performance. The present study provides further insight into risky decision making as a function of delusion proneness.

Cognitive ability and risk aversion: A systematic review and meta analysis

Are highly intelligent people less risk averse? Over the last two decades scholars have argued the existence of a negative relationship between cognitive ability and risk aversion. Although numerous studies support this, the link between cognitive ability and risk aversion has not been found consistently. To shed new light on this topic, a systematic review and meta-analysis was conducted. A total of 97 studies were identified and included for meta-analysis in the domain of gains (N=90, 723), 41 in the mixed domain (N=50, 936), and 12 in the domain of losses (N=4, 544). Results indicate that there exists a weak, but significant negative relationship between cognitive ability and risk aversion in the domain of gains. However, no relationship was observed in the mixed domain or in the domain of losses. Several meta-regressions were performed to investigate the influence of moderator variables. None of the moderator variables were found to consistently influence the relationship between cognitive ability and risk aversion across the domain of gains, mixed and losses. Moreover, no significant difference was observed between males and females across all three domains. In conclusion, this systematic review and meta-analysis provides new evidence that the relationship between cognitive ability and risk aversion is domain specific and not as strong as suggested by some previous studies.

Looking for Mr(s) Right: Decision bias can prevent us from finding the most attractive face

In realistic and challenging decision contexts, people may show biases that prevent them from choosing their favored options. For example, astronomer Johannes Kepler famously interviewed several candidate fiancées sequentially, but was rejected when attempting to return to a previous candidate. Similarly, we examined human performance on searches for attractive faces through fixed-length sequences by adapting optimal stopping computational theory developed from behavioral ecology and economics. Although economics studies have repeatedly found that participants sample too few options before choosing the best-ranked number from a series, we instead found overlong searches with many sequences ending without choice. Participants employed irrationally high choice thresholds, compared to the more lax, realistic standards of a Bayesian ideal observer, which achieved better-ranked faces. We consider several computational accounts and find that participants most resemble a Bayesian model that decides based on altered attractiveness values. These values may produce starkly different biases in the facial attractiveness domain than in other decision domains.

The simulation heuristic, paranoia, and social anxiety in a non-clinical sample

BACKGROUND AND OBJECTIVES

Quality of reasoning within non-clinical paranoia and mental simulation of future paranoia themed events was investigated by use of a simulation task to determine whether paranoid individuals would be restricted or more adept at reasoning about paranoia relevant material in comparison to a social anxiety group and a group with low paranoia and social anxiety.

METHOD

Participants (N = 63) were divided into the three groups based on paranoia and social anxiety scores. They were presented with the beginning and end of an imaginary situation and were asked to describe, step-by-step, what they imagined would happen between those two points. They were also administered a beads task to evaluate the jumping to conclusion decision making bias.

RESULTS

The prediction of more adept reasoning was not supported for paranoia. However, the social anxiety comparison group on average better simulated a scenario with congruent (socially anxious) thematic content compared to ones with non-congruent content. Further, in an exploratory analysis, jumping to conclusions bias was found to be positively related to goodness of simulation for paranoia themed scenarios within the paranoia group.

LIMITATIONS

Study groups were relatively small and so power was an issue.

CONCLUSION

The results are discussed in the context of the sometimes paradoxical findings in the area of cognitive biases and paranoia.

fMRI correlates of jumping-to-conclusions in patients with delusions: Connectivity patterns and effects of metacognitive training

Background

Reasoning biases such as the jumping-to-conclusions bias (JTC) are thought to contribute to delusions. Interventions targeting these biases such as metacognitive training (MCT) may improve delusions. So far, it is not clear whether JTC depends on dopaminergic reward areas that constitute the main action locus of antipsychotic drugs, or on additional cortical areas. The present study aimed to investigate fMRI activation and functional connectivity patterns underlying JTC, and their changes following MCT, in patients with delusions.

Methods

Participants were 25 healthy individuals and 26 patients with current delusions who were either medication-free or on stable medication without sufficient response. We assessed (1) BOLD activity in the task-positive (TPN), task-negative (TNN), and subcortical reward network (RN); (2) Psychophysiological interactions (PPI) of peak activation areas.

Results

Presence of JTC (irrespective of group) was associated with lower RN activity during conclusion events, and with increased effective connectivity between TPN and TNN during draw events. Following MCT, changes were observed in TPN activity and in effective connectivity of inferior parietal cortex (part of the TPN) with all three target networks.

Conclusion

JTC is associated not only with reward system areas that constitute the main target of antipsychotic drugs, but also with cortical areas, particularly of the TPN.

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Faulty evidence gathering (jumping to conclusions, JTC) is associated with delusions.

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We assessed data gathering with fMRI in patients with delusions vs healthy controls.

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JTC was associated with abnormal activity and connectivity patterns.

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Changes in the task-positive network were observed following metacognitive training.

How Do Delusion-Prone Individuals Respond to Disconfirmatory Evidence?

Abstract. Research employing the beads task suggests that people with delusional tendencies over-adjust to disconfirmatory evidence compared to low-delusion-prone individuals. This interpretation is in tension with studies using the bias against disconfirmatory evidence (BADE) task, which provide evidence that people with delusional tendencies are less receptive to disconfirmatory evidence. It has been suggested that over-adjustment on the beads task may be driven by miscomprehension of the task. The current preliminary study aimed to minimize miscomprehension on the beads task and determine how high-delusion-prone people respond to disconfirmatory evidence on both tasks. Fifty-one undergraduate participants completed the BADE task and an adapted version of the beads task. We expected that corrective feedback on the beads task would reduce miscomprehension, and that high-delusion-prone participants would be less receptive to disconfirmatory evidence on both tasks. Our results suggest this version of the beads task improved rates of comprehension relative to previous research. However, we found no evidence that the high-delusion-prone group demonstrated elevated over-adjustment or belief inflexibility in either task. The theoretical implications of these findings are discussed.

Analytic cognitive style, not delusional ideation, predicts data gathering in a large beads task study

INTRODUCTION

It has been proposed that deluded and delusion-prone individuals gather less evidence before forming beliefs than those who are not deluded or delusion-prone. The primary source of evidence for this "jumping to conclusions" (JTC) bias is provided by research that utilises the "beads task" data-gathering paradigm. However, the cognitive mechanisms subserving data gathering in this task are poorly understood.

METHODS

In the largest published beads task study to date (n = 558), we examined data gathering in the context of influential dual-process theories of reasoning.

RESULTS

Analytic cognitive style (the willingness or disposition to critically evaluate outputs from intuitive processing and engage in effortful analytic processing) predicted data gathering in a non-clinical sample, but delusional ideation did not.

CONCLUSION

The relationship between data gathering and analytic cognitive style suggests that dual-process theories of reasoning can contribute to our understanding of the beads task. It is not clear why delusional ideation was not found to be associated with data gathering or analytic cognitive style.

Bayesian accounts and black swans: Questioning the erotetic theory of delusional thinking

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.

The erotetic theory of delusional thinking

INTRODUCTION

In this paper, we argue for a novel account of one cognitive factor implicated in delusional cognition. According to the erotetic theory of delusion we present, the central cognitive factor in delusion is impaired endogenous question raising.

METHOD

After presenting the erotetic theory, we draw on it to model three distinct patterns of reasoning exhibited by delusional and schizophrenic patients, and contrast our explanations with Bayesian alternatives.

RESULTS

We argue that the erotetic theory has considerable advantages over Bayesian models. Specifically, we show that it offers a superior explanation of three phenomena: the onset and persistence of the Capgras delusion; recent data indicating that schizophrenic subjects manifest superior reasoning with conditionals in certain contexts; and evidence that schizophrenic and delusional subjects have a tendency to "jump to conclusions." Moreover, since the cognitive mechanisms we appeal to are independently motivated, we avoid having to posit distinct epistemic states that are intrinsically irrational in order to fit our model to the variety of data.

CONCLUSION

In contrast to Bayesian models, the erotetic theory offers a simple, unified explanation of a range of empirical data. We therefore conclude that it offers a more plausible framework for explaining delusional cognition.

Psychotic Experiences and Working Memory: A Population-Based Study Using Signal-Detection Analysis

Psychotic Experiences (PEs) during adolescence index increased risk for psychotic disorders and schizophrenia in adult life. Working memory (WM) deficits are a core feature of these disorders. Our objective was to examine the relationship between PEs and WM in a general population sample of young people in a case control study. 4744 individuals of age 17–18 from Bristol and surrounding areas (UK) were analyzed in a cross-sectional study nested within the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort study. The dependent variable was PEs, assessed using the semi-structured Psychosis-Like Symptom Interview (PLIKSi). The independent variable was performance on a computerized numerical n-back working memory task. Signal-Detection Theory indices, including standardized hits rate, false alarms rate, discriminability index (d’) and response bias (c) from 2-Back and 3-Back tasks were calculated. 3576 and 3527 individuals had complete data for 2-Back and 3-Back respectively. Suspected/definite PEs prevalence was 7.9% (N = 374). Strongest evidence of association was seen between PEs and false alarms on the 2-Back, (odds ratio (OR) = 1.17 [95% confidence intervals (CI) 1.01, 1.35]) and 3-back (OR = 1.35 [1.18, 1.54]) and with c (OR = 1.59 [1.09, 2.34]), and lower d’ (OR = 0.76 [0.65, 0.89]), on the 3-Back. Adjustment for several potential confounders, including general IQ, drug exposure and different psycho-social factors, and subsequent multiple imputation of missing data did not materially alter the results. WM is impaired in young people with PEs in the general population. False alarms, rather than poor accuracy, are more closely related to PEs. Such impairment is consistent with different neuropsychological models of psychosis focusing on signal-to-noise discrimination, probabilistic reasoning and impaired reality monitoring as a basis of psychotic symptoms.

Jumping to Conclusions About the Beads Task? A Meta-analysis of Delusional Ideation and Data-Gathering

It has been claimed that delusional and delusion-prone individuals have a tendency to gather less data before forming beliefs. Most of the evidence for this "jumping to conclusions" (JTC) bias comes from studies using the "beads task" data-gathering paradigm. However, the evidence for the JTC bias is mixed. We conducted a random-effects meta-analysis of individual participant data from 38 clinical and nonclinical samples (n = 2,237) to investigate the relationship between data gathering in the beads task (using the "draws to decision" measure) and delusional ideation (as indexed by the "Peters et al Delusions Inventory"; PDI). We found that delusional ideation is negatively associated with data gathering (r(s) = -0.10, 95% CI [-0.17, -0.03]) and that there is heterogeneity in the estimated effect sizes (Q-stat P = .03, I(2) = 33). Subgroup analysis revealed that the negative association is present when considering the 23 samples (n = 1,754) from the large general population subgroup alone (r(s) = -0.10, 95% CI [-0.18, -0.02]) but not when considering the 8 samples (n = 262) from the small current delusions subgroup alone (r(s) = -0.12, 95% CI [-0.31, 0.07]). These results provide some provisional support for continuum theories of psychosis and cognitive models that implicate the JTC bias in the formation and maintenance of delusions.

Jumping to conclusions in schizophrenia

Schizophrenia is a mental disorder associated with a variety of symptoms, including hallucinations, delusions, social withdrawal, and cognitive dysfunction. Impairments on decision-making tasks are routinely reported: evidence points to a particular deficit in learning from and revising behavior following feedback. In addition, patients tend to make hasty decisions when probabilistic judgments are required. This is known as "jumping to conclusions" (JTC) and has typically been demonstrated by presenting participants with colored beads drawn from one of two "urns" until they claim to be sure which urn the beads are being drawn from (the proportions of colors vary in each urn). Patients tend to make early decisions on this task, and there is evidence to suggest that a hasty decision-making style might be linked to delusion formation and thus be of clinical relevance. Various accounts have been proposed regarding what underlies this behavior. In this review, we briefly introduce the disorder and the decision-making deficits associated with it. We then explore the evidence for each account of JTC in the context of a wider decision-making deficit and then go on to summarize work exploring JTC in healthy controls using pharmacological manipulations and functional imaging. Finally, we assess whether JTC might have a role in therapy.