Jumping to conclusions and the persistence of delusional beliefs in first episode psychosis

Neurocognitive performance and cognitive biases in young adults with schizotypal traits

Recent research suggests that neurocognitive deficits in patients with schizophrenia may increase the risk of developing cognitive biases. As such, we set out to determine this predictive relationship as it pertains to the development of a first-episode psychosis. We hypothesized that poorer performance in processing speed would be associated with jumping to conclusions and an externalizing bias. Poorer performance in working memory would be associated with belief inflexibility and jumping to conclusions, and poorer performance in attention would be associated with attention to threat. We hypothesized that all cognitive biases would be associated with subsyndromal positive symptoms, and schizotypal traits would moderate these relationships. Undergraduate students (N = 130) completed the Schizotypal Personality Questionnaire, DAVOS Assessment of Cognitive Biases, Community Assessment of Psychic Experiences, and a computerized neuropsychological assessment battery. Processing speed had a small effect on externalizing bias, which in turn affected subsyndromal positive symptoms. There was no moderating effect of schizotypal traits on externalizing bias, but it was significantly associated with subsyndromal positive symptoms. Only the externalizing bias was associated with subsyndromal positive symptomatology, which might be explained by a restricted range and reduced variance in performance as a result of using a university student sample. This is one of few studies that sought to explain the mechanism responsible for the development of subsyndromal positive symptoms in a healthy sample using self-report measures.

A systematic review of performance-based assessment studies on cognitive biases in schizophrenia spectrum psychoses and clinical high-risk states: A summary of 40 years of research

Cognitive models of psychosis have stimulated empirical studies on cognitive biases involved in schizophrenia spectrum psychoses and their symptoms. This systematic review aimed to summarize the studies on the role of cognitive biases as assessed in different performance-based tasks in schizophrenia spectrum psychoses and clinical high-risk states. We focused on five cognitive biases linked to psychosis, i.e., aberrant salience, attentional biases, source monitoring biases, jumping to conclusions, and bias against disconfirmatory evidence. We identified N = 324 studies published in N = 308 articles fulfilling inclusion criteria. Most studies have been cross-sectional and confirmed that the schizophrenia spectrum psychoses are related to exaggerated cognitive biases compared to healthy controls. On the contrary, less evidence suggests a higher tendency for cognitive biases in the UHR sample. The only exceptions were source monitoring and jumping to conclusions, which were confirmed to be exaggerated in both clinical groups. Hallucinations and delusions were the most frequent symptoms studied in the context of cognitive biases. Based on the findings, we presented a hypothetical model on the role of interactions between cognitive biases or additive effects of biases in shaping the risk of psychosis. Future research is warranted for further development of cognitive models for psychosis.

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.

A pilot 1-year follow-up randomised controlled trial comparing metacognitive training to psychoeducation in schizophrenia: effects on insight

Poor insight in schizophrenia spectrum disorders (SSD) is linked with negative outcomes. This single-centre, assessor-blind, parallel-group 1-year follow-up randomised controlled trial (RCT) tested whether metacognitive training (MCT) (compared to psychoeducation) may improve insight and outcomes in outpatients with SSD assessed: at baseline (T0); after treatment (T1) and at 1-year follow-up (T2). Insight (primary outcome) was measured with (i) the Schedule for Assessment of Insight-Expanded version- (SAI-E), including illness recognition (IR), symptom relabelling (SR), treatment compliance (TC) and total insight scores (TIS); and (ii) the Beck Cognitive Insight Scale (BCIS). Between-group comparisons were nonsignificant, while within the MCT group (but not within controls) there was a significant medium effect size for improved TIS at T2 (d = 0.67, P = 0.02). Secondary outcomes included cognitive measures: Jumping to Conclusions (JTC), Theory of Mind (ToM), plus symptom severity and functioning. Compared to psychoeducation, MCT improved the PANSS excitement (d = 1.21, P = 0.01) and depressed (d = 0.76, P = 0.05) factors at T2; and a JTC task both at T1 (P = 0.016) and at T2 (P = 0.031). Participants in this RCT receiving MCT showed improved insight at 1-year follow-up, which was associated with better mood and reduced JTC cognitive bias. In this pilot study, no significant benefits on insight of MCT over psychoeducation were detected, which may have been due to insufficient power.

Heterogeneity in Response to MCT and Psychoeducation: A Feasibility Study Using Latent Class Mixed Models in First-Episode Psychosis

Metacognitive training (MCT) is an effective treatment for psychosis. Longitudinal trajectories of treatment response are unknown but could point to strategies to maximize treatment efficacy during the first episodes. This work aims to explore the possible benefit of using latent class mixed models (LCMMs) to understand how treatment response differs between metacognitive training and psychoeducation. We conducted LCMMs in 28 patients that received MCT and 34 patients that received psychoeducation. We found that MCT is effective in improving cognitive insight in all patients but that these effects wane at follow-up. In contrast, psychoeducation does not improve cognitive insight, and may increase self-certainty in a group of patients. These results suggest that LCMMs are valuable tools that can aid in treatment prescription and in predicting response to specific treatments.

Jumping to Conclusions and Its Associations With Psychotic Experiences in Preadolescent Children at Familial High Risk of Schizophrenia or Bipolar Disorder-The Danish High Risk and Resilience Study, VIA 11

BACKGROUND

The jumping to conclusions (JTC) bias, ie, making decisions based on inadequate evidence, is associated with psychosis in adults and is believed to underlie the formation of delusions. Knowledge on the early manifestations of JTC and its associations with psychotic experiences (PE) in children and adolescents is lacking.

DESIGN

Preadolescent children (mean age 11.9 y, SD 0.2) at familial high risk of schizophrenia (FHR-SZ, n = 169) or bipolar disorder (FHR-BP, n = 101), and controls (n = 173) were assessed with the Beads Task to examine JTC. The number of beads drawn before making a decision, "draws to decision" (DTD) was used as a primary outcome. PE were ascertained in face-to-face interviews. General intelligence was measured with Reynolds Intellectual Screening Test.

RESULTS

Children at FHR-SZ took fewer DTD than controls (4.9 vs 5.9, Cohen's d = 0.31, P = .004). Differences were attenuated when adjusting for IQ (Cohen's d = 0.24, P = .02). Higher IQ was associated with a higher number of DTD (B = 0.073, P < .001). Current subclinical delusions compared with no PE were associated with fewer DTD in children at FHR-SZ (P = .04) and controls (P < .05). Associations between delusions and DTD were nullified when accounting for IQ.

CONCLUSIONS

JTC marks familial risk of psychosis in preadolescence, not reducible to general intelligence. JTC is associated with subclinical delusions, but this may be an expression of intellectual impairment. Future studies should establish temporality between JTC and delusion formation and examine JTC as a target for early intervention.

Clinical insight and cognitive functioning as mediators in the relationships between symptoms of psychosis, depression, and suicide ideation in first-episode psychosis

First-episode psychosis (FEP) is a particularly high-risk period for suicide. Literature suggests poor cognitive functioning may serve as a protective factor, while investigations of clinical insight reveal a complex relationship with suicide outcomes. This study examined the mediating role of cognition and clinical insight in the relationships between positive and negative symptoms, depression, and subsequent suicide ideation among individuals in FEP. Data were obtained from the Recovery After an Initial Schizophrenia Episode project. Participants (n = 404) included adolescents and adults in FEP between the ages of 15 and 40. Measurement utilized the Calgary Depression Rating Scale, Positive and Negative Syndrome Scale, and Brief Assessment of Cognition in Schizophrenia. Structural equation modeling was used to examine the mediation model. The likelihood of experiencing suicide ideation was significantly decreased when working memory was stronger (b = -0.034, SE = 0.02, OR = 0.967, p < .05), and significantly increased when clinical insight was stronger (b = 0.191, SE = 0.08, OR = 1.21, p < .01), positive symptoms were greater (b = 0.422, SE = 0.20, OR = 1.52, p < .05) and depressive symptoms were greater (b = 0.545, SE = 0.15, OR = 1.70, p < .001). Clinical insight and working memory functioned as mediators in the relationships between depression, positive symptoms, negative symptoms, and suicide ideation. Findings suggest it is essential that clinicians have awareness of insight being a risk factor for suicide ideation and balance therapeutic efforts to strengthen clinical insight and cognition in psychosocial treatments with suicide risk assessment and prevention methods.

The relationship between early symptom severity, improvement and remission in first episode psychosis with jumping to conclusions

It is suggested that Jumping To Conclusions (JTC) reasoning bias might contribute to the distortion of external reality. However, the association between psychotic manifestations and JTC is obscure, especially if general intelligence is considered as a mediator. The aim of this study is to investigate the relation between severity, early clinical improvement and remission of symptoms in First Episode Psychosis (FEP) with JTC as an explanatory factor. One hundred seventy-one FEP individuals were evaluated with the Positive and Negative Syndrome Scale (PANSS) at baseline and one month after treatment initiation. Clinical improvement was ascribed as symptom change one-month post-baseline measurements. Symptomatic remission was assessed with the Andreasen severity criteria and JTC with the Beads Task, operationalized through Draws To Decision (DTD) (the lower the number of DTD, the higher the JTC bias). Regarding symptoms severity, total psychotic, total positive psychotic, and hallucinations-item PANSS scores showed a negative association with JTC after controlling for IQ. Regarding early clinical improvement, the association with JTC was non-significant. No significant association was detected between one month remission status of FEP and JTC. Our findings indicate that severity of positive symptoms is not associated with hastiness in decision-making, but rather with a heightened conservatism in terms of increased data gathering. Further research is required to replicate the results and clarify the cognitive processes involved.

Males and females with first episode psychosis present distinct profiles of social cognition and metacognition

Deficits in social cognition and metacognition impact the course of psychosis. Sex differences in social cognition and metacognition could explain heterogeneity in psychosis. 174 (58 females) patients with first-episode psychosis completed a clinical, neuropsychological, social cognitive, and metacognitive assessment. Subsequent latent profile analysis split by sex yielded two clusters common to both sexes (a Homogeneous group, 53% and 79.3%, and an Indecisive group, 18.3% and 8.6% of males and females, respectively), a specific male profile characterized by presenting jumping to conclusions (28.7%) and a specific female profile characterized by cognitive biases (12.1%). Males and females in the homogeneous profile seem to have a more benign course of illness. Males with jumping to conclusions had more clinical symptoms and more neuropsychological deficits. Females with cognitive biases were younger and had lower self-esteem. These results suggest that males and females may benefit from specific targeted treatment and highlights the need to consider sex when planning interventions.

Unstable Belief Formation and Slowed Decision-making: Evidence That the Jumping-to-Conclusions Bias in Schizophrenia Is Not Linked to Impulsive Decision-making

BACKGROUND

Jumping-to-conclusions (JTC) is a prominent reasoning bias in schizophrenia (SCZ). While it has been linked to not only psychopathological abnormalities (delusions and impulsive decision-making) but also unstable belief formation, its origin remains unclear. We here directly test to which extend JTC is associated with delusional ideation, impulsive decision-making, and unstable belief formation.

METHODS

In total, 45 SCZ patients were compared with matched samples of 45 patients with major depressive disorder (MDD) and 45 healthy controls (HC) as delusions and JTC also occur in other mental disorders and the general population. Participants performed a probabilistic beads task. To test the association of JTC with measures of delusions (Positive and Negative Syndrome Scale [PANSS]positive, PANSSpositive-factor, and Peter Delusions Inventory [PDI]), Bayesian linear regressions were computed. For the link between JTC and impulsive decision-making and unstable beliefs, we conducted between-group comparisons of "draws to decision" (DTD), "decision times" (DT), and "disconfirmatory evidence scores" (DES).

RESULTS

Bayesian regression obtained no robust relationship between PDI and DTD (all |R2adj| ≤ .057, all P ≥ .022, all Bayes Factors [BF01] ≤ 0.046; α adj = .00833). Compared with MDD and HC, patients with SCZ needed more time to decide (significantly higher DT in ambiguous trials: all P ≤ .005, r2 ≥ .216; numerically higher DT in other trials). Further, SCZ had unstable beliefs about the correct source jar whenever unexpected changes in bead sequences (disconfirmatory evidence) occurred (compared with MDD: all P ≤ .004 and all r2 ≥ .232; compared with HC: numerically higher DES). No significant correlation was observed between DT and DTD (all P ≥ .050).

CONCLUSIONS

Our findings point toward a relationship of JTC with unstable belief formation and do not support the assumption that JTC is associated with impulsive decision-making.

Social cognition and interaction training for recent-onset schizophrenia: A preliminary randomized trial

Comprehensive social cognition training programs have been effective to improve social cognition in people with chronic schizophrenia, although there is insufficient quality evidence for recent-onset psychosis. The aim of this study was to assess the effects of Social Cognition and Interaction Training (SCIT) in a sample of recent-onset schizophrenia outpatients. Sixteen participants who had their first psychotic episode for less than 2 years were randomly allocated to the SCIT group during 20 weeks (weekly sessions) or to a psychoeducation group and completed baseline and post-training assessment for cognitive biases, social cognition, clinical symptoms and functioning. Permutation-based analysis revealed improvements in overall functioning (P = 0.036) and blame score (P = 0.070) in the SCIT group compared to the psychoeducation intervention, with large effect sizes (d = 1.438 and d = 1.204, respectively). There were also large effect sizes for hostility, emotion recognition, social perception, positive and total symptoms (d = 0.833-1.158). These results suggest that SCIT may be an effective tool to improve attributional biases and functional outcomes in recent-onset schizophrenia outpatients. Future controlled trials with larger sample size and follow-up assessments should be developed to further understand effective intervention outcomes for this population.

The influence of risk factors on the onset and outcome of psychosis: What we learned from the GAP study

The GAP multidisciplinary study carried out in South London, recruited 410 first episode of psychosis patients and 370 controls; the aim was to elucidate the multiple genetic and environmental factors influencing the onset and outcome of psychosis. The study demonstrated the risk increasing effect of adversity in childhood (especially parental loss, abuse, and bullying) on onset of psychosis especially positive symptoms. Adverse life events more proximal to onset, being from an ethnic minority, and cannabis use also played important roles; indeed, one quarter of new cases of psychosis could be attributed to use of high potency cannabis. The "jumping to conclusions" bias appeared to mediate the effect of lower IQ on vulnerability to psychosis. We confirmed that environmental factors operate on the background of polygenic risk, and that genetic and environment act together to push individuals over the threshold for manifesting the clinical disorder. The study demonstrated how biological pathways involved in the stress response (HPA axis and immune system) provide important mechanisms linking social risk factors to the development of psychotic symptoms. Further evidence implicating an immune/inflammatory component to psychosis came from our finding of complement dysregulation in FEP. Patients also showed an upregulation of the antimicrobial alpha-defensins, as well as differences in expression patterns of genes involved in NF-κB signaling and Cytokine Production. Being of African origin not only increased risk of onset but also of a more difficult course of illness. The malign effect of childhood adversity predicted a poorer outcome as did continued use of high potency cannabis.

Jumping to conclusions at first onset of psychosis predicts longer admissions, more compulsory admissions and police involvement over the next 4 years: the GAP study

BACKGROUND

Jumping to conclusions (JTC), which is the proneness to require less information before forming beliefs or making a decision, has been related to formation and maintenance of delusions. Using data from the National Institute of Health Research Biomedical Research Centre Genetics and Psychosis (GAP) case-control study of first-episode psychosis (FEP), we set out to test whether the presence of JTC would predict poor clinical outcome at 4 years.

METHODS

One-hundred and twenty-three FEP patients were assessed with the Positive and Negative Syndrome Scale (PANSS), Global Assessment of Functioning (GAF) and the probabilistic reasoning 'Beads' Task at the time of recruitment. The sample was split into two groups based on the presence of JTC bias. Follow-up data over an average of 4 years were obtained concerning clinical course and outcomes (remission, intervention of police, use of involuntary treatment - the Mental Health Act (MHA) - and inpatient days).

RESULTS

FEP who presented JTC at baseline were more likely during the follow-up period to be detained under the MHA [adjusted OR 15.62, 95% confidence interval (CI) 2.92-83.54, p = 0.001], require intervention by the police (adjusted OR 14.95, 95% CI 2.68-83.34, p = 0.002) and have longer admissions (adjusted IRR = 5.03, 95% CI 1.91-13.24, p = 0.001). These associations were not accounted for by socio-demographic variables, IQ and symptom dimensions.

CONCLUSIONS

JTC in FEP is associated with poorer outcome as indicated and defined by more compulsion police intervention and longer periods of admission. Our findings raise the question of whether the implementation of specific interventions to reduce JTC, such as Metacognition Training, may be a useful addition in early psychosis intervention programmes.

Cost Evaluation During Decision-Making in Patients at Early Stages of Psychosis

Jumping to conclusions during probabilistic reasoning is a cognitive bias reliably observed in psychosis and linked to delusion formation. Although the reasons for this cognitive bias are unknown, one suggestion is that psychosis patients may view sampling information as more costly. However, previous computational modeling has provided evidence that patients with chronic schizophrenia jump to conclusions because of noisy decision-making. We developed a novel version of the classical beads task, systematically manipulating the cost of information gathering in four blocks. For 31 individuals with early symptoms of psychosis and 31 healthy volunteers, we examined the numbers of "draws to decision" when information sampling had no, a fixed, or an escalating cost. Computational modeling involved estimating a cost of information sampling parameter and a cognitive noise parameter. Overall, patients sampled less information than controls. However, group differences in numbers of draws became less prominent at higher cost trials, where less information was sampled. The attenuation of group difference was not due to floor effects, as in the most costly block, participants sampled more information than an ideal Bayesian agent. Computational modeling showed that, in the condition with no objective cost to information sampling, patients attributed higher costs to information sampling than controls did, Mann-Whitney U = 289, p = 0.007, with marginal evidence of differences in noise parameter estimates, t(60) = 1.86, p = 0.07. In patients, individual differences in severity of psychotic symptoms were statistically significantly associated with higher cost of information sampling, ρ = 0.6, p = 0.001, but not with more cognitive noise, ρ = 0.27, p = 0.14; in controls, cognitive noise predicted aspects of schizotypy (preoccupation and distress associated with delusion-like ideation on the Peters Delusion Inventory). Using a psychological manipulation and computational modeling, we provide evidence that early-psychosis patients jump to conclusions because of attributing higher costs to sampling information, not because of being primarily noisy decision makers.

Neuropsychological functioning and jumping to conclusions in recent onset psychosis patients

BACKGROUND

The reasoning bias of jumping to conclusions (JTC) consists of a tendency to make assumptions having little information.

OBJECTIVE

The aim of this study was to estimate the differences in neuropsychological functioning between recent onset psychotic patients who jump to conclusions and those who do not jump to conclusions.

MATERIALS AND METHODS

One hundred and twenty-two patients with a recent onset of a psychotic disorder were assessed with three JTC tasks and a neuropsychological battery exploring verbal learning, memory, attention, psychomotor speed, visuoperceptual abilities, working memory, problem solving, executive functioning.

RESULTS

A total of 29.7% (n=36) of the individuals jumped to conclusions in Task 1, 14.0% (n=17) in Task 2, and 15.7% (n=19) in Task 3. People who jump to conclusions in three tasks scored significantly worse in many neuropsychological domain deficits, including attention (p<0.001-0.020), psychomotor speed (p<0.001), working memory (p<0.001-0.040), and executive functioning (p<0.001-0.042).

DISCUSSION

The present study demonstrates that JTC is present even in early stages of the illness, and that there is a relationship between JTC and neuropsychological functioning.

Intranasal oxytocin does not modulate jumping to conclusions in schizophrenia: Potential interactions with caudate volume and baseline social functioning

BACKGROUND

Patients with schizophrenia (SCZ) tend to sample less information when making a decision, jumping to conclusions (JTC) without sufficient evidence. This "JTC bias" may be a trait marker of the disease and may not improve with antipsychotic treatment. We conducted a double-blind, placebo-controlled trial to test whether intranasal oxytocin could reduce JTC in stable, medicated patients with SCZ and healthy controls (HCs). We also explored whether striatal volume, clinical symptoms, and baseline social functioning (SF) was related to JTC performance.

METHODS

Forty-three male, medicated SCZ patients (Mean Age: 40.81±11.44) and sixteen HCs (Mean Age: 30.38±9.85) participated in a double-blind, placebo-controlled, cross-over study. Participants completed the Beads Task on two separate visits (minimum 20days apart). Participants were randomized to receive either intranasal oxytocin (50IU in solution) or intranasal placebo (saline). Twenty of the SCZ patients and all sixteen HCs also provided T1 MRIs (3-T).

RESULTS

Patients with SCZ took fewer draws to decision (DTD) than HCs (t(57)=2.78, p=0.007). Oxytocin did not significantly change DTD in patients (t(42)=-1.11, p=0.27), nor in HCs (t(15)=-0.62, p=0.55). Exploratory analyses found ventral caudate volumes were negatively correlated with DTD (r(18)=-0.50, p=0.03) in patients. Moreover, oxytocin was more likely to improve JTC in patients with lower baseline SF. However, these exploratory findings did not survive correction for multiple comparisons.

CONCLUSIONS

We replicate increased JTC in SCZ. However, acute intranasal oxytocin did not modify JTC. Future studies with larger samples should explore how brain morphology and SF are related to JTC performance in patients with SCZ.

Randomized control trial to assess the efficacy of metacognitive training compared with a psycho-educational group in people with a recent-onset psychosis

BACKGROUND

Aims were to assess the efficacy of metacognitive training (MCT) in people with a recent onset of psychosis in terms of symptoms as a primary outcome and metacognitive variables as a secondary outcome.

METHOD

A multicenter, randomized, controlled clinical trial was performed. A total of 126 patients were randomized to an MCT or a psycho-educational intervention with cognitive-behavioral elements. The sample was composed of people with a recent onset of psychosis, recruited from nine public centers in Spain. The treatment consisted of eight weekly sessions for both groups. Patients were assessed at three time-points: baseline, post-treatment, and at 6 months follow-up. The evaluator was blinded to the condition of the patient. Symptoms were assessed with the PANSS and metacognition was assessed with a battery of questionnaires of cognitive biases and social cognition.

RESULTS

Both MCT and psycho-educational groups had improved symptoms post-treatment and at follow-up, with greater improvements in the MCT group. The MCT group was superior to the psycho-educational group on the Beck Cognitive Insight Scale (BCIS) total (p = 0.026) and self-certainty (p = 0.035) and dependence self-subscale of irrational beliefs, comparing baseline and post-treatment. Moreover, comparing baseline and follow-up, the MCT group was better than the psycho-educational group in self-reflectiveness on the BCIS (p = 0.047), total BCIS (p = 0.045), and intolerance to frustration (p = 0.014). Jumping to Conclusions (JTC) improved more in the MCT group than the psycho-educational group (p = 0.021). Regarding the comparison within each group, Theory of Mind (ToM), Personalizing Bias, and other subscales of irrational beliefs improved in the MCT group but not the psycho-educational group (p < 0.001-0.032).

CONCLUSIONS

MCT could be an effective psychological intervention for people with recent onset of psychosis in order to improve cognitive insight, JTC, and tolerance to frustration. It seems that MCT could be useful to improve symptoms, ToM, and personalizing bias.

Who "jumps to conclusions"? A comprehensive assessment of probabilistic reasoning in psychosis following traumatic brain injury (PFTBI), and comparison with TBI, schizophrenia, and nonclinical controls

INTRODUCTION

The "jumping to conclusions" (JTC) bias has received significant attention in the schizophrenia and delusion literature as an important aspect of cognition characterising psychosis. The JTC bias has not been explored in psychosis following traumatic brain injury (PFTBI).

METHODS

JTC was investigated in 10 patients with PFTBI using the beads task (ratios 85:15 and 60:40). Probabilistic predictions, draws-to-decision, self-rated decision confidence, and JTC bias were recorded. Responses from 10 patients with traumatic brain injury (TBI), 23 patients with schizophrenia, and 23 nonclinical controls were compared. Relationships were explored between draws-to-decision and current intelligence quotient, affective state, executive function, delusions (severity and type), and illness chronicity (duration).

RESULTS

Groups were comparable on JTC measures. Delusion severity and type were not related to draws-to-decision for either trial. In the entire sample, executive function (reduced mental flexibility) was significantly related to more draws-to-decision on the 60:40 ratio trial.

CONCLUSIONS

We found no evidence for an elevated JTC bias in patients with PFTBI or TBI alone. The influence of executive dysfunction should be considered by future studies using the beads tasks in patient populations. These findings need to be replicated in larger PFTBI and TBI samples.

Psychosis, Delusions and the "Jumping to Conclusions" Reasoning Bias: A Systematic Review and Meta-analysis

We did a systematic review and meta-analysis to investigate the magnitude and specificity of the "jumping to conclusions" (JTC) bias in psychosis and delusions. We examined the extent to which people with psychosis, and people with delusions specifically, required less information before making decisions. We examined (1) the average amount of information required to make a decision and (2) numbers who demonstrated an extreme JTC bias, as assessed by the "beads task." We compared people with psychosis to people with and without nonpsychotic mental health problems, and people with psychosis with and without delusions. We examined whether reduced data-gathering was associated with increased delusion severity. We identified 55 relevant studies, and acquired previously unpublished data from 16 authors. People with psychosis required significantly less information to make decisions than healthy individuals (k= 33,N= 1935,g= -0.53, 95% CI -0.69, -0.36) and those with nonpsychotic mental health problems (k= 13,N= 667,g= -0.58, 95% CI -0.80, -0.35). The odds of extreme responding in psychosis were between 4 and 6 times higher than the odds of extreme responding by healthy participants and participants with nonpsychotic mental health problems. The JTC bias was linked to a greater probability of delusion occurrence in psychosis (k= 14,N= 770, OR 1.52, 95% CI 1.12, 2.05). There was a trend-level inverse association between data-gathering and delusion severity (k= 18;N= 794;r= -.09, 95% CI -0.21, 0.03). Hence, nonaffective psychosis is characterized by a hasty decision-making style, which is linked to an increased probability of delusions.