Signal detection in the psychotic phenotype: Increased sensory precision and reduced decision threshold associated with psychotic-like experiences

Psychotic-like experiences may reflect disrupted signal detection, whereby individuals detect signals in noisy input that are unlikely to be present. Drawing on predictive coding accounts, we investigated whether increased sensory precision and reduced data-gathering relate to psychotic-like experiences in a signal detection task. We fitted drift-diffusion models to Random Dot Motion (RDM) task data completed by 191 participants. Drift rate (proxy of sensory precision) and decision threshold were estimated: 1) across groups differing in psychotic phenotypes, and 2) as outcomes in regression models with psychotic-like experiences as predictors. We also tested whether reduced data-gathering on the beads task replicated prior associations with psychotic phenotypes. Hallucination- and delusion-like experiences were associated with increased drift rates. Hallucination-like experiences also predicted lower decision thresholds. In the beads task, psychotic-like experiences correlated with higher confidence ratings but not with reduced data-gathering. Our findings indicate that psychotic-like phenomenology is linked to increased precision of signal detection. Overprecise signal detection may increase the likelihood of false positives, potentially leading to anomalous experiences. Alterations of signal detection mechanisms may play a key role in psychosis proneness and, potentially, contribute to the development of psychotic symptoms.