Are people more selfish after giving gifts?

How people choose gifts is a widely studied topic, but what happens next is largely understudied. In two preregistered studies, one field experiment, and an analysis of secondary data, we show that giving gifts has a dark side, as it can negatively affect subsequent interpersonal behavior between givers and receivers. In Study 1, we found that giving a gift to one's romantic partner changes givers' interpretation of which behaviors constitute infidelity. Specifically, we found that givers (vs. nongivers) classified their questionable behaviors (e.g., sending a flirtatious text to someone other than their partner) less as a form of cheating on their partner. In Study 2, we examined how politely participants behave when delivering bad news to a friend. We found that givers (vs. nongivers) wrote significantly less polite messages to their friend. In Study 3, we tested real gifts that people give to friends and found givers (vs. nongivers) subsequently made more selfish decisions at their friends' expense. In all, our research refines the oft-cited axiomatic assumption that gift giving strengthens relationships and illuminates the potential for future research to examine how decision making can alter interpersonal, romantic relationships.