Beyond the cross-section: Rethinking the intention-behaviour gap through a conceptual and methodological lens.

Objectives
The intention-behaviour gap (IBG) remains a persistent challenge in health psychology. While intentions are widely recognized as proximal determinants of behaviour, they frequently fail to translate into action. This conceptual review aims to critically evaluate dominant models of the IBG and propose a dynamic, multidimensional reconceptualization of intention-behaviour processes.Methods
This conceptual review critically evaluates dominant models of the IBG-the Explained Variance Approach and the Action Control Framework. Special emphasis is placed on methodological constraints associated with between-person research designs, which inadequately capture the temporal and contextual variability of behavioural enactment.Results
Theoretical and empirical limitations are identified in existing IBG models, including their failure to address intra-individual fluctuations, situational contingencies and the time-indexed nature of behavioural regulation. In response, we propose a framework emphasizing intensive longitudinal designs, within-person assessment, ecological momentary methods and person-specific modelling techniques to better capture intention-behaviour dynamics.Conclusions
To close the IBG, future research should integrate dynamic methodologies and real-time interventions that align with situational and motivational states. We advocate for context-sensitive strategies, such as just-in-time adaptive interventions and implementation intentions, to enhance behavioural enactment. This reconceptualization offers a pathway towards more precise theory and effective intervention in health behaviour change.