Seven Key Terms in Behavioural Research: Developing Agreed Ontological Definitions

Behavioural research is a multidisciplinary field essential for addressing societal challenges, but it suffers from inconsistent terminology that impedes knowledge synthesis and communication across disciplines. This study used consensus methods to develop informal and ontological definitions for seven key behavioural research terms: individual behaviour, population behaviour, individual behaviour change, behavioural theory, behavioural research, behavioural science, and leadership. Using a seven-step iterative method involving a literature review, expert consultations, and feedback from diverse behavioural researchers and users, the team refined definitions to enhance clarity, inclusivity, and cross-disciplinary understanding. The resulting definitions were accompanied by elaborations and examples to provide context and concrete illustrations of the terms. These shared definitions provide a standardised vocabulary to improve study and intervention design and reporting, evidence synthesis, and translation of evidence into policy and practice. While acknowledging limitations such as sample bias, this work lays a foundation for clearer communication and future advances in behavioural research.