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 the factors which improve trust in the systems. Our issue here was to explore whether 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: (i) a function-oriented written presentation (G1), (ii) a use-oriented written presentation, “augmented” with difficult situations (G2) and (iii) 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 realised, after reading 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.
The use of a new technological tool, whether it is a question of human–machine- or human–human-mediated cooperation, leads to transformation of human activity, often in the direction of a modification of the control and the initiative of the activity by the user. Mastery of the situation and of the power to act can thus diminish; and this loss of control, i.e. delegated to another human or machine, may be compensated for by the trust that it is acceptable. It may be very uncomfortable to delegate the control of an activity to a tool or to a person that one does not trust. People tend to seek emotional comfort and well-being, and in a risky situation which can generate fear for instance, they will need to interact with an object or a person that they trust, to reduce this feeling of fear and to reinstall emotional comfort. We define this notion of emotional comfort and discomfort (Cahour, 2008) as a global feeling, which is dynamically constructed through the affective states (trust, fear, surprise, etc.) lived by a user during a specific activity, and which involves the body and the mind. It is important to consider the comfort/discomfort of the users, besides their efficiency and performance, for the ergonomic evaluation and design, since the effective use of new tools depends on both (El Jaafari et al., 2008). Lheureux et al. (2004) find that, among users of the cruise control systems, the two most frequently cited motives, for owning such a system are “comfort” (around 40%) and “not having to worry about police checks” (around 35%), which is, according to us, a typical issue of emotional comfort too.
In a risk situation (such as that of driving a car) and in environments whose evolution is uncertain, human beings are potentially threatened and rendered fragile; they thus need to consider that the tools that they use are reliable and efficient, and that they can predict their behaviour, otherwise they could involve taking personal risks, of accident for instance.
Trust (and distrust, which is its inseparable opposite) has been studied in relation to control of dynamic systems (Amalberti, 1996, Muir, 1994 and Rajaonah et al., 2003), often within interpersonal frameworks (Rempel et al., 1985 and Josang et al., 2005). Muir and Morais (1996) have shown that the use of an automatic system increases as a function of the trust that is accorded to it and a new system for assisting driving, which modifies the control of the activity of changing gear, seems to be particularly susceptible to depending on this sentiment of trust. Rajaonah et al. (2003) have in any case shown that the less drivers have trust in a regulator, the more they prefer to deactivate it.
One of the functions of trust is to reduce complexity and uncertainty (Muir, 1994). since one of the characteristics of a complex system is that the interactions between components are unpredictable, when one reduces complexity by making one element in the environment reliable and predictable (trustable), it allows the subject to limit the perceived risk.
