Federalism is often presented through metaphors, such as the metaphor of the family or of a – crazy – machine, but little is known about the impact of such metaphors on citizens. In the previous edition of the Conference Belgium: The State of the Federation, we presented an experiment assessing the impact of the real-life Tetris metaphor on citizens’ representations and preferences about federalism. The experiment, conducted in Belgium, was made of different groups, controlling for the presence, in a text, of a metaphor. The results showed that being exposed to the text with the Tetris metaphor does influence the participants’ representations of federalism towards a more institutional representation and above all more regional autonomy. On this basis, we conducted a new experiment, testing for the specific impact of the metaphor (text with metaphor and text without metaphor, as well as a control group, without any text and therefore metaphor). The results confirmed the importance of the text, but also more specifically of the metaphor. What is even more interesting is that we could test for the interaction between political knowledge and the impact of the metaphor. These tests reveal that the respondents with a lower level of political knowledge are indeed those who are influenced by the metaphors, while the respondents with a higher level are not impacted. These findings are important both for the study of federalism in Belgium and the study of the complex interactions between discourse and political preferences.