Is an eye truly for an eye? Magnitude differences affect moral praise more than moral blame

Does the amount of perceived moral responsibility correspond to the magnitude of the act to the same degree regardless of whether the act is moral or immoral? In four experiments (N = 1617; all preregistered), we found that—when evaluating two agents who performed similar acts but with different magnitude—observers judged greater differences in their moral responsibility when those acts were moral than when they were immoral. That is, the same difference in magnitude had greater influence on perceived moral responsibility for moral acts compared to immoral acts. Furthermore, we also found that the asymmetry effect impacted perceivers' judgment of the moral character of the agent (Studies 2 and 3). Evaluating immoral (vs. moral) acts led participants to use a more affect-based (vs. reason-based) decision mode, which, in turn, led them to be more scope insensitive to the magnitude difference of the two acts (Study 3). Lastly, we showed that this asymmetry effect is moderated by the individual's concern with the relevant moral issue (Study 4). When perceivers care less about the issue (e.g., animal welfare), the asymmetry effect attenuates. These results together suggest that, when comparing the moral responsibility of different moral agents, magnitude of behavior matters more for positive than for negative acts.