The rising prevalence of neurodegenerative diseases such as dementia and Parkinson’s disease poses a critical challenge as the global population continues to age. Enhancing cognitive reserve through cognitive training, particularly via neurofeedback (NFB), has become a promising strategy to counteract cognitive decline. This thesis presents a comprehensive study on the development and evaluation of a novel NFB training system designed to enhance attention in healthy adults. The system leverages event-related potentials (ERPs) and iterative learning control (ILC) to dynamically personalise task difficulty, thereby optimising training efficiency and engagement. The research is underpinned by extensive data collection, involving a large-scale clinical trial with a significant sample size of healthy adult participants. The trial rigorously tested the system efficacy, providing robust evidence of its effectiveness. Participants were divided into groups, with one group receiving ILC-adapted training and others following traditional or random difficulty protocols. The results demonstrate that the ILC group not only completed the training more rapidly but also achieved substantial improvements in attention, validated by both behavioural metrics and neurophysiological markers. Further investigations within this thesis address the system practicality, including studies on reducing the number of EEG electrodes to improve usability. The potential transferability of attentional improvements to motor skill acquisition in surgical training is also explored, revealing insights that guide future research in this domain. In conclusion, this thesis contributes significantly to the field of cognitive training by showcasing the potential of ERP-based NFB systems in enhancing attention through large-scale, real-world clinical trials. The findings open new avenues for applying such systems in broader cognitive training and rehabilitation contexts, with recommendations for future studies to explore long-term impacts and cross-domain applicability.