Affect Dynamics or Response Bias? Extreme Response Style in Daily-Life Assessments.

Intensive longitudinal data (ILD) are increasingly used to study affect dynamics such as intraindividual variability and inertia. These parameters are often interpreted as substantive individual differences, yet they may be biased by stable response style tendencies, in particiular extreme response style (ERS). In the present study, we investigated whether ERS is systematically associated with affect dynamics estimated from multiple experience sampling method (ESM) datasets (total N=1,254). Using a joint Bayesian IRTree-location-scale modeling approach, we estimated person-specific ERS alongside affective variability and inertia across multiple ESM datasets and synthesized study-level associations using a meta-analytic approach. We find that higher ERS is consistently associated with greater intraindividual variability. In contrast, we find no evidence that ERS was related to affective or emotional inertia. These results suggest that commonly used measures of intraindividual variability may partly reflect systematic response behavior rather than solely genuine affective fluctuations. Ignoring ERS may therefore bias variability estimates obtained from location-scale and related multilevel dynamic models. Overall, this study highlights the importance of accounting for response styles when modeling affect dynamics and interpreting person-specific variability parameters in ILD research.