Figure 1.

Illustration of experimental design and trial procedure. A, We used a 2 × 2 within-subject design by independently manipulating Audience (Private or Public) and Moral Context (Good or Bad), which yielded four experimental conditions (i.e., Public_Good, Public_Bad, Private_Good, and Private_Bad). The Public condition was indicated by the picture of “eyes,” and the Private condition was indicated by the picture of a “lock.” The Good Context involved a tradeoff between personal losses and benefits for a charity, whereas in the Bad Context participants traded personal benefits against benefits for a morally bad cause. B, Monetary payoffs (in Brazilian Real) for participants (8 levels: from 1 to 8, in steps of 1) and the association (8 levels: from 4 to 32, in steps of 4) were orthogonally varied, yielding 64 unique offers for each condition. In the example trial (one for the Public_Good and the other for the Private_Bad condition), participants were presented with an offer and decided whether to accept or reject the offer with no time limit. If they accepted the offer, both parties involved (i.e., the participant and the association) might undergo the financial consequences as proposed. If they rejected the offer, neither party would profit. In the Private condition, once a response was made, the screen was unchanged for 0.5 s to keep the chosen option private. In the Public condition, the chosen option was highlighted with a larger font and the nonchosen option disappeared, this lasted slightly longer (1.5 s) to further emphasize the presence of a witness. Each trial was ended with an intertrial interval (ITI) showing a jittered fixation (2.5 ∼ 6.5 s).