Abstract: Self-signaling models predict less selfish behavior in a probabilistic giving setting as individuals are predicted to invest in a pro-social identity. However, there is also substantial evidence that people tend to exploit situational excuses for selfish choices (for instance, uncertainty) and behave more selfishly. We contrast these two motivations experimentally in order to test which one is more prevalent in a reciprocal giving setting. Trustees’ back transfer choices are elicited for five different transfer levels of the trustor.