Robots that Take Advantage of Human Trust Humans often assume that robots are rational. We believe robots take optimal actions given their objective; hence, when we are uncertain about what the robotxe2x80x99s objective is, we interpret the robotxe2x80x99s actions as optimal with respect to our estimate of its objective. This approach makes sense when robots straightforwardly optimize their objective, and enables humans to learn what the robot is trying to achieve. However, our insight is thatxe2x80x93when robots are aware that humans learn by trusting that the robot actions are rationalxe2x80x93intelligent robots do not act as the human expects; instead, they take advantage of the humanxe2x80x99s trust, and exploit this trust to more efficiently optimize their own objective. In this paper, we formally model instances of humanrobot interaction (HRI) where the human does not know the robotxe2x80x99s objective using a twoplayer game. We formulate different ways in which the robot can model the uncertain human, and compare solutions of this game when the robot has conservative, optimistic, rational, and trusting human models. In an offline linearquadratic case study and a realtime user study, we show that trusting human models can naturally lead to communicative robot behavior, which influences endusers and increases their involvement.

Human Trust After Robot Mistakes: Study of the Effects of Different Forms of Robot Communication Collaborative robots that work alongside humans will experience service breakdowns and make mistakes. These robotic failures can cause a degradation of trust between the robot and the community being served. A loss of trust may impact whether a user continues to rely on the robot for assistance. In order to improve the teaming capabilities between humans and robots, forms of communication that aid in developing and maintaining trust need to be investigated. In our study, we identify four forms of communication which dictate the timing of information given and type of initiation used by a robot. We investigate the effect that these forms of communication have on trust with and without robot mistakes during a cooperative task. Participants played a memory task game with the help of a humanoid robot that was designed to make mistakes after a certain amount of time passed. The results showed that participantsxe2x80x99 trust in the robot was better preserved when that robot offered advice only upon request as opposed to when the robot took initiative to give advice.