Publication
Cost evaluation during decision making in patients at early stages of psychosis
Publisher:
Cold Spring Harbor Laboratory
Date:
15-12-2017
DOI:
10.1101/225920
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 s ling 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 in iduals with early symptoms of psychosis and 31 healthy volunteers, we examined the numbers of ‘draws to decision’ when information s ling had no, a fixed, or an escalating cost. Computational modelling involved estimating a cost of information s ling parameter and a cognitive noise parameter. Overall patients s led less information than controls. However, group differences in numbers of draws became less prominent at higher cost trials, where less information was s led. The attenuation of group difference was not due to floor effects, as in the most costly block participants s led more information than an ideal Bayesian agent. Computational modelling showed that, in the condition with no objective cost to information s ling, patients attributed higher costs to information s ling 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, in idual differences in severity of psychotic symptoms were statistically significantly associated with higher cost of information s ling (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 s ling information, not because of being primarily noisy decision makers.