Exploring automated vehicle driving styles as a source of trust information

Abstract

Trust is important for users’ acceptance and adoption of automated vehicles (AVs). Previous research has mainly focused on what information affects user trust in AVs and how the user’s trust is affected by the way the content is communicated. However, recent studies have shown that trust may also be affected by the AV’s driving style. The aim of the study was to further investigate if and how the vehicle’s driving style affects user trust in AVs and, in particular, how this is expressed by users. An experiment involving 18 participants, using a Wizard of Oz setup and within a subject design, was conducted comparing two different driving styles, ‘Defensive’ and ‘Aggressive’. Trust was measured using a mixed method research design including momentaneous trust ratings and think-aloud procedures while driving, a post-run trust questionnaire as well as trust curve sketching and a personal interview. The results show that driving style had an effect on user trust and that the ‘Defensive’ driving style was perceived as more trustworthy, in part because it was deemed more predictable than the ‘Aggressive’ driving style. Furthermore, participants expressed trust in using affective, analogical and analytic responses, the two former during the test runs and the latter directly after each test run. The interview after the completion produced a more mixed result. By combining different data collection methods, a nuanced picture of the trust formation process and users’ trust in AVs was obtained. The study concludes that it is important to consider the vehicle performance information provided by the vehicle’s driving style so as to create user trust in AVs.