The Impact of Autonomous Vehicles' Active Feedback on Trust

The successful introduction of self-driving technology may depend on the ability of the vehicles' human-machine interface to convey trust to the vehicle occupants. Using a driving simulator, in this experiment we aimed to evaluate drivers' trust on an autonomous system, depending on the feedback the vehicle provided by an assistive cluster's interface. Forty participants were divided into three groups regarding levels of feedback: (a) cluster without feedback (N = 13); (b) cluster with feedback regarding the surrounding vehicles (N = 14); (c) cluster with feedback regarding the surrounding vehicles and the vehicle's own decisions (N = 13). For all groups, a visual search task was introduced as an indirect indicator of trust in the autonomous system. Results showed an inverse relation between available feedback and correct answers. The system was evaluated as trustable and safe by all groups. Overall, the results may contribute to design requirements for future vehicle HMIs, as they indicate that more information does not necessarily convey more trust.