Abstract
Alterations in decision-making are proposed to underlie several psychiatric disorders, such as psychosis.
Decision-making involves integrating information about future outcomes, such as their probability, reward
value, and effort cost. This process is shaped by the comparison between expected and actual outcomes,
commonly described in terms of prediction errors. In psychosis, aberrant prediction error signalling is thought
to bias belief formation toward unlikely or implausible outcomes, contributing to hallucinations and delusions.
Additionally, impairments in decision-making have been linked to negative symptoms, particularly motivational
deficits. I will present evidence for these alterations across different cohorts – from healthy adolescents with
psychotic-like experiences to individuals with chronic schizophrenia – using a range of tasks, including an
orthogonalised Go/No-Go task, the Two-Step task, and the Balloon Analogue Risk task combined with
computational modelling. These behavioural measures offer scalable, cost-effective tools for probing
mechanisms underlying psychotic symptoms.