To praise or to blame? Neural signals predict divergent responses to moral hypocrisy

Abstract Moral hypocrisy is common in society and could be discouraged if observers always respond negatively. Understanding the observers’ responses to moral hypocrisy is critical for promoting genuine morality. This study took the perspective from the observers and compared their behavioral and neural responses to moral hypocrisy versus clear moral/immoral acts. Behaviorally, we found that claiming to help but avoiding the cost of help (i.e., moral hypocrisy) was endorsed as more moral than rejecting to help and even received monetary praise from 40% of observers. Neurally, moral hypocrisy versus clear moral acts elicited reduced responses in the reward system (e.g., ventromedial prefrontal cortex) and increased responses in regions responsible for disgust (e.g., anterior insula). The neural signals together with the interplay to the mentalizing network (e.g., temporoparietal junction) predicted divergent responses, even five months later. Our findings provide behavioral and neural accounts of how hypocrisy is perceived and why it prevails. Significance Statement From the perspective of a third-party observer, this study showed that moral hypocrisy is indeed deceptive and induces observers’ divergent responses of praise or blame. Claiming to help but avoiding the cost of help (i.e., moral hypocrisy) was considered more moral than rejecting to help and even received monetary praise from 40% of observers. Using fMRI, this study revealed that the divergent behavioral responses to moral hypocrisy could be predicted and classified by the activations of the reward system (e.g., ventromedial prefrontal cortex) and regions responsible for disgust (e.g., anterior insula) as well as the functional connectivity with the mentalizing network (e.g., right temporoparietal junction), even five months later.