Factor analysing predictive processing: No evidence for a general factor across tasks

Dysfunctional predictive processing (PP), specifically the aberrant weighting of priors, is a frequently-proposed mechanism for psychosis and schizotypy. Evidence mostly originates from single-task studies, which assume that all tasks measure a single latent construct of PP performance, but the underlying factor structure of PP tasks is unknown. PP deficits in psychosis may be better described by a two-factor, hierarchical model: weakened lower-level (perceptual) priors compensated by higher-level (cognitive) priors.

We implemented a multi-paradigm approach in a preliminary sample of healthy participants (N = 73) to investigate latent constructs underlying PP and their relationship to schizotypy. Participants completed 6 tasks measuring reliance on priors across language, memory, visual, and auditory domains. A factor analysis investigated whether performance across tasks is captured by a single or two-factor model.

Although a two-factor model best described performance, factors reflected within-task correlations rather than a PP hierarchy. Cross-task PP measures were poorly correlated, potentially due to unreliable outcomes and the task-specific weighting of priors. A full model including all task outcomes (not factors) only significantly predicted the severity of schizotypal aberrant beliefs.

These results do not indicate a single or two-factor hierarchical model of PP. It may be inappropriate to use results from single tasks to propose a generalised PP deficit in schizotypy/psychosis. Further multi-paradigm research with larger samples and different tasks is required to confirm these findings and evaluate alternative models that may describe PP. Future directions for creating standardised paradigms with reliable outcomes are discussed.