Morality on the road: Should machine drivers be more utilitarian than human drivers?

Machines powered by artificial intelligence have the potential to replace or collaborate with human decision-makers in moral settings. In these roles, machines would face moral tradeoffs, such as automated vehicles (AVs) distributing inevitable risks among road users. Do people believe that machines should make moral decisions differently from humans? If so, why? To address these questions, we conducted six studies (N = 6805) to examine how people, as observers, believe human drivers and AVs should act in similar moral dilemmas and how they judge their moral decisions. In pedestrian-only dilemmas where the two agents had to sacrifice one pedestrian to save more pedestrians, participants held them to similar utilitarian norms (Study 1). In occupant dilemmas where the agents needed to weigh the in-vehicle occupant against more pedestrians, participants were less accepting of AVs sacrificing their passenger compared to human drivers sacrificing themselves (Studies 1-3) or another passenger (Studies 5-6). The difference was not driven by reduced occupant agency in AVs (Study 4) or by non-voluntary occupant sacrifice in AVs (Study 5), but rather by the perceived social relationship between AVs and their users (Study 6). Thus, even when people adopt an impartial stance as observers, they are more likely to believe that AVs should prioritize serving their users in moral dilemmas. We discuss the theoretical and practical implications for AV morality.