At this juncture, the participant was to decide if she would return more (altruistic act), equal to (honest act), or less (deceptive act) than the amount defined by (R×N×x). But if the participant decided to lie to the trustee and this deception

was discovered, all money in the trial would be confiscated as punishment. The participant was reminded that she could not pay more than the appreciated investment (N×x) or less than the amount of investment (x). In each trial, after a pseudorandomized interval meant to mimic a real human decision, the amount of investment (x, which was an integer generated from Inhibitors,research,lifescience,medical four intervals: 10–20, 30–45, 55–70, and 75–90) was click here presented on the screen, followed by the appreciated investment (N×x, N being a rational number selected from four intervals, that is,

the investment multiplier: 1–1.2, 1.4–1.6, 2.4–2.6, and 2.8–3). The screen also showed for 2 sec the proportion (R) of the investment Inhibitors,research,lifescience,medical the trustee should repay the investor and the probability (P) that the investor would discover how much the trustee actually paid back. Afterward, the participant was asked to fill in the amount she would like to repay to the investor (M). If the amount Inhibitors,research,lifescience,medical of repaid money was larger than that requested, it was considered “altruistic.” But if this amount was less than requested (R×N×x), the participant’s response was considered “deceptive.” The participant executed the decision by pressing the spacebar. She then waited Inhibitors,research,lifescience,medical for 2 sec to be informed of the money acquired in this trial and whether her deception had been detected by the investor. If the deceptive act was caught, all money acquired in the trial would be confiscated as punishment. There were three R values of requested repayment proportions (20%, 50%, and 80%), which could be defined as “beneficial,”“equal,” and “unfair.” The risk of being detected Inhibitors,research,lifescience,medical was defined by two P values corresponding to a 25% (low) and a 75% (high) chance of being

detected. In total, there were 96 trials corresponding to the conditions combined by the levels of R, P, N, and x (3 × 2 × 4 × 4 = 96). All trials were presented randomly. The important dependent measures were frequency of choice and ratio of choice. Frequency of choice meant the number of a type of choice (deceptive or altruistic) relative Tolmetin to all choices made, and indicated the qualitative preference of the participants in social decision making, that is, deception or altruism. The ratio of choice reflected the quantitative preference in choice. If a participant decided to be deceptive, the ratio of choice was the difference between the amount actually repaid and the amount that should be repaid relative to the largest amount that the participant could acquire if she played deception. On the other hand, if the choice was altruism, the ratio of choice was the difference between the amount actually repaid and amount that should be repaid compared with the largest amount that one could repay the investor altruistically.