Response: Commentary: Outlining a novel psychometric model of mental flexibility and affect dynamics

We thank Ionescu and Gros for their thought-provoking commentary, which continues an important discussion on the conceptual foundations of Flexibility. The term Flexibility has long suffered from fragmentation across domains—cognitive, behavioral, affective, and psychological—leading to inconsistent operationalizations and reduced theoretical clarity. Cognitive Flexibility, in particular, is often treated either as the core construct or as entirely distinct from broader forms such as behavioral regulation or experiential openness in therapeutic models like ACT. In our model, we propose Mental Flexibility as a unifying, overarching construct that integrates these diverse expressions. Defined as an emergent capacity for adaptive variability, Mental Flexibility accounts for both changes in behavior and the maintenance of self-coherence across shifting contexts. Due to Flexibility's strong connection to the concept of variability, which involves shifting or changing, our framework also explores its interplay with affect dynamics, highlighting how shifts in cognition and behavior correspond to emotional fluctuations. The critiques addressed here pertain to conceptual clarity, measurement issues, and our theoretical positioning within the variability-stability-flexibility continuum.