The well-known experiments of Nisbett and Wilson lead to the conclusion that we have no introspective access to our decision-making processes. Johansson et al. have recently developed an original protocol consisting in manipulating covertly the relationship between the subjects' intended choice and the outcome they were presented with: in 79.6% of cases, they do not detect the manipulation and provide an explanation of the choice they did not make, confirming the findings of Nisbett and Wilson. We have reproduced this protocol, while introducing for some choices an expert guidance to the description of this choice. The subjects who were assisted detected the manipulation in 80% of cases. Our experiment confirms Nisbett and Wilson's findings that we are usually unaware of our decision processes, but goes further by showing that we can access them through specific mental acts.

We know that the systems which are trusted by the users are more often used, especially in a risky situation where they need to delegate control, but we still ignore largely which are the factors which improve trust in the systems. Our issue here was to explore if the way we present the system to the users will have an effect on their confidence in it. In this study, we had nine subjects using for the first time a Cruise Control System on open road; before, we present the system to them in three different ways: a function-oriented written presentation (G1); a use-oriented written presentation, "augmented" with difficult situations (G2); a use-oriented film presentation (3). They evaluate their trust in the system on scales before the whole experiment, after the presentation and after the real use. At the end, they also have self-confrontation interviews, where they see the video of their driving and describe their activity, strategies and feelings. We then develop quantitative and qualitative analysis of trust, linked with specific situations of action. Our results indicate that the presentation of instructions lowers the evaluation of trust (and of efficiency) that conductors have a priori; they had constructed an a priori representation of a CCS that is rather idealistic, and realise, after reading of the instructions, and above all after having watched a film, that its use is not so obvious as they had previously thought. There is thenceforth a drop in trust that nevertheless goes up again after use of the system during driving. We remark, from qualitative analyses of use experience of the regulator in real driving conditions that this drop in trust in the system does not inhibit subjects in their use, and in particular, for subjects who have watched a film of projection into use. They know more of the functions of the system in driving conditions, they produce less distorted reconstruction of the functioning, and they have a deeper level of understanding of the system.