Neural correlates of individual differences in moral judgment competence

Abstract

Normative judgment – the evaluation of actions with respect to social norms and values – entails a number of processes represented by a distributed network of brain regions. People differ with respect to their competence to make moral judgments. In this study we investigated how individual differences in this domain modulate neural correlates of simple normative judgments. Sentences including violations of social norms and grammatical rules were presented visually in a mixed blocked/ event-related design. Social norm violations were designed not to create emotional arousal. 23 participants decided whether sentences were normatively or grammatically correct while their brain activity was monitored using functional magnetic resonance imaging. To assess emotional arousal skin conductance was recorded. Individual differences in moral judgment competence were assessed using the Moral Judgment Test (C-score; Lind, 2001). Normative judgments compared to grammatical judgments resulted in activation of temporal poles, left ventromedial prefrontal cortex, left orbitofrontal cortex, and left posterior Sulcus temporalis superior (mixed effects, p<0.001, uncorr.). There was no correlation between C-scores and response times during either task, however changes in brain activity in right dorsolateral prefrontal cortex (DLPFC, BA 45/46) during normative as compared to grammatical judgments covaried with C-scores. A region of interest analysis showed that C-scores correlated negatively with blood oxygen level-dependent responses in right DLPFC during normative (rNORM=-0.47, p<0.05) but not during grammatical judgments (rgram=-0.05, p=0.41). In this study we contrasted normative judgments devoid of emotional arousal with grammatical judgments. Our data are in line with previous studies which found a similar functional neural network contributing to a number of tasks ranging from simple moral decisions to complex dilemmatic moral judgments. Moreover, we provide first evidence that individual differences in moral judgment competence modulate neural correlates of normative judgments. When making normative judgments, participants with higher competence recruited the right DLPFC less than those with less ability in this domain. This might indicate lower processing demands of participants with higher moral judgment competence.