This paper is a research proposal for a Ph.D. study. The aim of this work is to discover effects of human aspects (eg., gender, age, seniority, educational background) on threat analysis. To contribute to this body of knowledge, we are conducting a state-of-the-art literature review and several experiments with human participants (experts and non-experts) in the domain of security and risk assessment. First, the topic and technical domain are described in general. Second, preliminary results of the on-going literature review are presented. Finally, a research plan is described including research questions, treatment, and participant recruitment.