Cost evaluation during decision making in patients at early stages of psychosis

Abstract

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 modelling has provided evidence that patients with chronic schizophrenia jump to conclusion 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 modelling 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 modelling showed that, in the condition with no objective cost to information sampling, patients attributed higher costs to information sampling than controls (Mann-Whiney U=289, p=0.007), with marginal evidence of differences in noise parameter estimates (t=1.86 df=60, p=0.07). In patients, individual differences in severity of psychotic symptoms were statistically significantly associated with higher cost of information sampling (rho=0.6, p=0.001) but not with more cognitive noise (rho=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 modelling, 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.

Jumping To Conclusions, General Intelligence, And Psychosis Liability: Findings From The Multi-Centre EU-GEI Case-Control Study

“…In other words, first episode psychosis patients gathered less evidence and made hasty decisions only if they presented a lower IQ than controls. Previous studies focusing on different explanations between the JTC bias and psychotic disorders suggested that deluded patients tend to request less information because sampling itself might be experienced as more costly than it would be by healthy people 43,44 . Although patients at onset seem to adjust their strategy according to the cost of sampling where clearly stated and show more bias to sample less information in the classic task, general cognitive ability still plays an important role in their decision-making behaviour 43,44 .…”

“…Previous studies focusing on different explanations between the JTC bias and psychotic disorders suggested that deluded patients tend to request less information because sampling itself might be experienced as more costly than it would be by healthy people 43,44 . Although patients at onset seem to adjust their strategy according to the cost of sampling where clearly stated and show more bias to sample less information in the classic task, general cognitive ability still plays an important role in their decision-making behaviour 43,44 . Indeed, the inclusion of general cognitive ability in the relation between JTC and clinical status was reported to substantially decrease or nullify a prior significant association 15,26,28 .…”

“…Although the sample size is several times larger than any individual previous study, it is still modest by genomic standards. We only included a single trial of the task, as previous research has indicated that the measure of draws to decision is very reliable over trials 44,50 , to facilitate data collection in this large multi-centre study. It can be argued that only performing one trial using the higher cognitive demanding 60:40 version could capture more miscomprehension of the task rather than truly the bias, resulting in overestimating its presence 51,52 .…”

“…Nonetheless, future research is warranted to explore more specific cognitive mediation, such as working memory and executive functions 7,22,28 , between JTC and psychosis using more trials of the Beads Task. The inclusion of more trials in future studies would permit a more detailed interrogation of the task 44,50 . For example, the use of multiple trials allows modelling of latent variables such as the probing of the distinct roles of cognitive noise and alterations in the perceived "cost" of information sampling, which may have partially distinct genetic bases.…”

Inflexible social inference in individuals with subclinical persecutory delusional tendencies

“…inference based on integrating observations with prior beliefs) as the cause of delusion formation (Coltheart et al, 2010;Hemsley and Garety, 1986). The notion that delusional ideation may be associated with abnormal inference has previously been related to the Jumping to Conclusions (JTC) bias in delusions (e.g., (Garety et al, 1991;Peters and Garety, 2006;So et al, 2012;Speechley et al, 2010); but see (Ermakova et al, 2017;Moutoussis et al, 2011)…”