Sults Monte Carlo Simulation with 
One-Shot GamesEach participant was 
chosen as an Roscovitine web unconditional decision maker, on average, 2664.57 times (SD = 57.74). The mean number of times chosen as a conditional decision maker was 891.52 (SD = 29.16). The mean BIRB796 payoff as an unconditional decision maker was 25.91 points (SD = 2.60; Table 8). The payoff was strongly negatively correlated with the UC2 (rho = -0.971, p < 0.0001; Table 9, first column), indicating that cooperativenessFrontiers in Psychology | www.frontiersin.orgApril 2015 | Volume 6 | ArticleHiraishi et al.Heritability of cooperative behaviorTABLE 8 | Mean, SD, and correlation with Study 2 decisions for payoffs in Study 3. Uncond. M SD 25.91 2.60 Cond. 28.17 2.07 It. = 2 25.88 1.60 It. = 5 24.50 0.85 It. = 10 23.83 0.61 It. = 20 23.53 0.55 It. = 50 23.33 0.55 It. = 100 23.27 0.Uncond. denotes payoffs for unconditional decision makers in simulations without iteration; Cond., payoffs for conditional decision makers in simulations without iteration; It., the number of iterations (It. = 2 through 100, denoting simulations with 2, 5,10, 20, 50, and 100 iterations). TABLE 9 | Correlations between Study 2 decisions and payoffs in Study 3. Scores UC2 LC2 MC2 HC2 Uncond. -0.971 -0.520 -0.549 -0.539 Cond. -0.535 -0.902 -0.959 -0.851 It. = 2 -0.836 -0.828 -0.871 -0.790 It. = 5 -0.711 -0.925 -0.865 -0.752 It. = 10 -0.510 -0.854 -0.707 -0.582 It. = 20 0.136 -0.271 -0.020 0.108 It. = 50 0.302 -0.034 0.246 0.385 It. = 100 0.340 0.047 0.331 0.All correlation coefficients were significant (p < 0.0001) except for those indicated in italics. Uncond. denotes payoffs for unconditional decision makers in simulations without iteration; Cond., payoffs for conditional decision makers in simulations without iteration; It., the number of iterations (It. = 2 through 100, denoting simulations with 2, 5,10, 20, 50, and 100 iterations); UC, unconditional; LC, lowest conditional; MC, medium C; HC, highest C.led to lesser payoffs. The mean payoff as a conditional decision maker was 28.17 points (SD = 2.07; Table 8). The payoffs were strongly negatively correlated with conditional decision scores in Study 2 (Table 9, second column), again suggesting that those who were more cooperative earned less. The difference between the payoff as an unconditional decision maker and that as a conditional decision maker was significant, indicating that the payoffs were larger for conditional decision makers [t(281) = 16.137, p < 0.0001]. We conducted univariate genetic analyses in the same manner as in Study 2 for the payoffs (Table 10). The results for unconditional decision maker payoffs were almost identical to those for unconditional decision scores in Study 2. The mean estimate of additive genetic factors was 22 while most of the phenotypic variances were explained by non-shared environmental factors (68 ). The parameter estimates for conditional decision makers indicated that most of the phenotypic variances were explained by non-shared environmental factors (67 ) while additive genetic factors explained 19 and shared environmental factors explained 14 .Monte Carlo Simulation with Iterated GamesThe mean payoffs per round were larger when the numbers of iterations were smaller (Table 8). Correlations between decision scores and payoffs showed particular patterns (Table 9). The correlation coefficients were negative when the number of iterations was small, but they were positive when the number of iterations was large. We visua.Sults Monte Carlo Simulation with One-Shot GamesEach participant was chosen as an unconditional decision maker, on average, 2664.57 times (SD = 57.74). The mean number of times chosen as a conditional decision maker was 891.52 (SD = 29.16). The mean payoff as an unconditional decision maker was 25.91 points (SD = 2.60; Table 8). The payoff was strongly negatively correlated with the UC2 (rho = -0.971, p < 0.0001; Table 9, first column), indicating that cooperativenessFrontiers in Psychology | www.frontiersin.orgApril 2015 | Volume 6 | ArticleHiraishi et al.Heritability of cooperative behaviorTABLE 8 | Mean, SD, and correlation with Study 2 decisions for payoffs in Study 3. Uncond. M SD 25.91 2.60 Cond. 28.17 2.07 It. = 2 25.88 1.60 It. = 5 24.50 0.85 It. = 10 23.83 0.61 It. = 20 23.53 0.55 It. = 50 23.33 0.55 It. = 100 23.27 0.Uncond. denotes payoffs for unconditional decision makers in simulations without iteration; Cond., payoffs for conditional decision makers in simulations without iteration; It., the number of iterations (It. = 2 through 100, denoting simulations with 2, 5,10, 20, 50, and 100 iterations). TABLE 9 | Correlations between Study 2 decisions and payoffs in Study 3. Scores UC2 LC2 MC2 HC2 Uncond. -0.971 -0.520 -0.549 -0.539 Cond. -0.535 -0.902 -0.959 -0.851 It. = 2 -0.836 -0.828 -0.871 -0.790 It. = 5 -0.711 -0.925 -0.865 -0.752 It. = 10 -0.510 -0.854 -0.707 -0.582 It. = 20 0.136 -0.271 -0.020 0.108 It. = 50 0.302 -0.034 0.246 0.385 It. = 100 0.340 0.047 0.331 0.All correlation coefficients were significant (p < 0.0001) except for those indicated in italics. Uncond. denotes payoffs for unconditional decision makers in simulations without iteration; Cond., payoffs for conditional decision makers in simulations without iteration; It., the number of iterations (It. = 2 through 100, denoting simulations with 2, 5,10, 20, 50, and 100 iterations); UC, unconditional; LC, lowest conditional; MC, medium C; HC, highest C.led to lesser payoffs. The mean payoff as a conditional decision maker was 28.17 points (SD = 2.07; Table 8). The payoffs were strongly negatively correlated with conditional decision scores in Study 2 (Table 9, second column), again suggesting that those who were more cooperative earned less. The difference between the payoff as an unconditional decision maker and that as a conditional decision maker was significant, indicating that the payoffs were larger for conditional decision makers [t(281) = 16.137, p < 0.0001]. We conducted univariate genetic analyses in the same manner as in Study 2 for the payoffs (Table 10). The results for unconditional decision maker payoffs were almost identical to those for unconditional decision scores in Study 2. The mean estimate of additive genetic factors was 22 while most of the phenotypic variances were explained by non-shared environmental factors (68 ). The parameter estimates for conditional decision makers indicated that most of the phenotypic variances were explained by non-shared environmental factors (67 ) while additive genetic factors explained 19 and shared environmental factors explained 14 .Monte Carlo Simulation with Iterated GamesThe mean payoffs per round were larger when the numbers of iterations were smaller (Table 8). Correlations between decision scores and payoffs showed particular patterns (Table 9). The correlation coefficients were negative when the number of iterations was small, but they were positive when the number of iterations was large. We visua.
