Faced with the proliferation of fake news and the public's credulity, education in critical thinking and the development of informational skills are becoming increasingly urgent. The credibility given to information depends largely on schemes, i.e. the usual ways of processing this information. This notion of scheme is similar, in the documentary context, to the concept of informational habitus (Vivion, 2019). Inspired by the theoretical frameworks of cognitive ergonomics, in particular the instrumental approach (Rabardel, 1995), we propose to see the processes of epistemic vigilance as a diagnostic activity. We develop the idea that the level of schemes, insufficiently addressed in dual models (Kahneman & Clarinard, 2016) constitutes the privileged level of articulation between automatic processes and analytical thinking. In conclusion, we discuss the implications of these proposals for education.