| A resurgence of interest in moral judgment led to functional neuroimaging investigations of how subjects generate such judgments. Evidence from a series of studies demonstrated the recruitment of a variety of neural structures in moral judgment, including ventromedial prefrontal cortex (vmPFC), orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), and dorso-lateral prefrontal cortex (dlPFC) among others. Moreover, increased activation in dlPFC and ACC was associated with utilitarian moral judgments to emotionally provocative problems, whereas non-utilitarian judgments involved greater activation in vmPFC. There is, however, a large literature linking vmPFC, OFC, and dlPFC to action planning. Based on this, the Discounted Expected Moral Value (DEMV) model is proposed linking action-planning algorithms derived from reinforcement learning theory with moral judgment. This model is tested on a published dataset and found to be statistically superior to a variety of competitor models. Experiment 1 tests the distinction between discounting over representations of states in an action sequence versus an explicit representation of the passage of time. Both are found to influence moral judgment; moral approval is lower for sacrificing one person to save multiple others if there are many intervening, but nevertheless necessary, states between the sacrifice and the benefit as well as if greater time is described as passing, regardless of the number of states. Experiment 2 tests the state-action sequence discounting hypothesis directly by altering the ordering of states in otherwise identical action sequences. As predicted, moral approval is greater for action sequences in which a strongly negative state occurs later in the action sequence than when the same state occurs sooner. Experiment 3 tests the simplifying assumption of the DEMV that all subjects share the same immediate valuation of the individual states that make up an action sequence. Individual differences in sensitivity to rewards, indexed via the Behavioral Inhibition and Behavioral Activation/Approach scales, strongly predict moral judgment. Experiment 4 responds to criticism of the original dual process model, of which the DEMV is an augmentation, by showing that the data to which the DEMV is fit does show reliable behavioral effects in both judgments and response times. |
