# Increased intra-subject variability in reward behavior relates to symptom severity in schizophrenia

## TL;DR

People with schizophrenia show more inconsistent behavior during reward tasks, and this inconsistency is linked to the severity of their symptoms.

## Contribution

This study is the first to show increased intra-subject variability in reward behavior in schizophrenia and its correlation with symptom severity.

## Key findings

- Increased intra-subject variability in response times, accuracy, and liking ratings in schizophrenia patients.
- Intra-subject variability across different behavioral measures is significantly correlated.
- Higher intra-subject variability is associated with greater symptom severity as measured by PANSS.

## Abstract

Schizophrenia (SZ) is a complex disorder characterized by positive and negative symptoms that have been linked to dysfunction in cognition and reward motivation. Recent findings show higher inter-subject variability in SZ in various cognitive functions. This raises the question of whether there is also higher intra-subject variability in SZ at the psychological level, specifically increased variability across the trials of a psychological task within the subject itself, that is, intra-subject variability. To examine fluctuations in behavior during a reward-based discrimination and liking task, we analyzed intra-subject variability in SZ and observed the following: (i) increased intra-subjective variability across all four behavioral measures, that is, response times (RT) for discrimination and liking tasks, as well as accuracy (ACC) and liking ratings; (ii) significant correlation of the different measures’ intra-subject variabilities across the distinct tasks, e.g., RT, ACC, and liking ratings among each other; and (iii) relation of the increased intra-subjective variability in the behavioral measures (RT, ACC, liking) with overall and general psychopathological symptom severity, as measured by the positive and negative syndrome scale (PANSS). Together, we demonstrate abnormally increased intra-subjective variability in a reward-motivation task in SZ and its key role in relation to symptom severity. This increased intra-subject variability at the psychological-behavioral level suggests abnormal and imprecise timing in cognitive processing, which aligns with analogous findings of temporal imprecision at the neural level.