Phantom Costs in Human-Robot Interaction: A Replication Study

A recent psychology study found that people are more likely to reject an overly generous offer from an agent (human or robot) when there is no clear justification. This “money backfire effect” is said to stem from perceived phantom costs (e.g., agent's bad intentions). However, their online version provided less clear results. To test its robustness, we conducted a high-powered direct replication study aiming to know whether money backfiring and phantom costs effects occur in human-robot interaction. A human or robot offered participants a cookie with or without money. Participants had to decide whether they would eat the cookie and answer some questions regarding the scenario. Results indicated that participants perceived more phantom costs when the offer included money, negatively influencing their decisions to eat the cookie. However, participant's likelihood to eat the cookie did not differ as a function of agent and offer. This study provides new insights regarding the validity of online studies. We advise scholars to adapt their study setting regarding the effect they want to explore.