In an era characterised by increasing cyber threats, there is a pressing need to gain a deeper understanding of how to enhance digital resilience at the individual level. In this study, we compared the role of actual knowledge with individuals’ perceived knowledge , and the influence on the intentions to engage in self-protective behaviour. Participants (N = 222) completed an online questionnaire , which included an actual knowledge test focusing on protection measures and items measuring constructs of Protection Motivation Theory. Our regression analyses showed that actual knowledge is a predictor to engage in self-protective behaviour, with a stronger influence than perceived knowledge. Both actual and perceived knowledge are vital for self-protective behaviour, however, they activate different types of efficacy. Actual knowledge is a stronger predictor of response efficacy, whereas perceived knowledge better predicts self-efficacy. We explored implications for intervention and future research in the discussion, by highlighting the need for prioritising knowledge dissemination , increasing user confidence, and the effectiveness of interventions. This paper is a substantial adaptation of a previous conference paper (Bluhm et al., 2025).