The widespread adoption of digital interfaces, amplified by the worldwide drive for digital inclusion, presents unique challenges, especially for older adults navigating the online realm. This research investigates aging populations' pronounced susceptibility to phishing schemes—a sophisticated digital threat with significant financial and societal implications. This study seeks to explore human-computer interaction (HCI) security for older adults, examining the interplay of heuristic and deliberate decision-making processes while accounting for age-related cognitive changes, behavioural attributes, and experiential factors. A comprehensive 2x2x2 factorial experimental design is proposed, which integrates variances in message themes (health and finance), gain-loss framing, and age disparities. The research harnesses Neuro Information Systems (NeuroIS) techniques, including EEG and eye-tracking, combined with questionnaires, to capture users' dynamic perceptions during phishing encounters. The anticipated findings aspire to shape HCI guidelines tailored for aging populations while contributing to developing user-centric security awareness programs and digital interfaces, mitigating cyber threat repercussions.