In everyday life discussion, people try to persuade each other about the goodness of their viewpoint regarding a certain topic. This persuasion process is usually affected by several elements, like the ability of the speaker in formulating logical arguments, her confidence with respect to the discussed topic, and the emotional solicitation that certain arguments may cause in the audience. In this study, we compare the effect of using one of the three well-known persuasion strategies (Logos, Ethos and Pathos) in the argumenta-tion process. These strategies are used by a moderator who influences the participants during the debates. We study which persuasion strategy is the most effective, and how they vary according to two mental metrics extracted from electroencephalograms: Engagement and workload. Results show that the right hemisphere has the highest engagement when Logos arguments are proposed to participants with Neutral opinion during the debate. We show also that the Logos strategy solicits the highest mental Workload, and the Pathos strategy is the most effective to use in argumentation and to convince the participants.