Fig. 1.

Single trial settings. On the first screen, subjects saw the first alternative comprising of a payoff for the subject in yellow and for the charity in blue (A). After a jittered time interval, the second alternative appeared. Subjects had up to 3 s to select one alternative by button-press (B). Note that the trials are randomly drawn from all possible combinations of decision situations. This results in a randomization of the order of payoff alternatives (see Methodological Details in Supplementary Material). The selected alternative was presented as a response feedback (C). After a jittered time interval, a fourth screen appeared, informing subjects whether the trial was discarded (red cross) or confirmed (green check) to be among the trials from which the actual payoff trial would be chosen (D). In the second part of the experiment, confirmed outcomes from part 1 were presented (screen one in part 2; C in Figure 1), subjects were informed on a second screen whether the trial was discarded or confirmed (D).