Antimicrobial resistance is a major global health challenge. It threatens the achievement of multiple SDGs with disproportionately negative consequences for LMICs. AMR is associated with the misuse of antibiotics, which is especially dominant in livestock farming. On-farm biosecurity has been identified as an effective way to prevent diseases. This requires a change in the daily behaviours of farmers. While the application of social-psychological models gained immense popularity in veterinary and agricultural research, these models lack predictive and explanatory character, leading to the so-called intention-action gap. The emerging field of behavioural sciences likely offers a better explanation of human behaviour, however, studies published often lack use of an explicit theoretical framework. Therefore, this exploratory study aims to address this gap by using Kahneman’s Dual-Process Theory as a theoretical framework for behaviour science studies. To this end, a qualitative study with 15 smallholder poultry farmers in rural Ghana was conducted. The findings suggested the presence of cognitive biases and heuristics that hinder farmers’ uptake of biosecurity measures, such as temporal discounting, social cues, cognitive overload, psychological inertia and habits. However, all factors must be considered, including knowledge gaps, as well as practical and economic constraints. It is clear from the study that farmers are not a homogenous group and that any promotion of biosecurity is destined to fail if they do not take farmers' psychological and contextual reality into consideration. Therefore, this thesis concludes that additional insights and hypotheses can be generated using behavioural science and that it offers a better and more holistic theoretical framework than currently used behavioural change models. Suggestions for further work include more empirical study in farmer decision-making related to on-farm biosecurity from a behavioural lens. Specifically, the use of quantitative and experimental methods to investigate and confirm the hypotheses that emerged from this study.