Moral judgment can be defined as the evaluation of actions with respect to norms and values established in a society (such as not stealing or being an honest citizen). When judging a behavior as morally good or bad, people refer to their internal representations of these norms and values (i.e. emotionally laden internal moral orientations or principles).
Psychological research on moral judgment has long been dominated by a developmental approach investigating the maturation of moral orientations and principles and emphasized the role of conscious and rational reasoning processes (Kohlberg, 1969
). Conversely, more recent models emphasize the role of unconscious and intuitive processes in moral judgment (Blair, 1995
; Haidt, 2001
; Hauser, 2006
; Hauser et al.
; Mikhail, 2007
). The social intuitionist model by Haidt (2001
), for example, posits that fast and automatic intuitions are the primary source of moral judgments, whereas conscious deliberations are only used to construct post hoc
justifications for judgments that have already occurred. Although there is some evidence supporting this view, others argue that immediate intuitions can also be informed by conscious deliberation (Pizarro and Bloom, 2003
) and that some moral principles are available to conscious reason while others are not (Cushman et al.
In addition to this current debate, neuropsychological models claim that emotions are important to adapt behavior to environmental demands (Damasio, 1996
). In line with this view, studies on patients with brain lesions showed that damage to the prefrontal cortex (especially its ventromedial and orbitofrontal portions) leads to deficits in social behavior and moral decision making (Damasio et al.
; Dimitrov et al.
; Koenigs and Tranel, 2007
; Koenigs et al.
Investigating the question of how moral judgments are made in healthy subjects, a number of recent neuroimaging studies identified a network of brain regions contributing to moral cognition. Although these studies used different tasks ranging from simple moral decisions (Moll et al.
; Heekeren et al.
; Luo et al.
) to complex dilemmatic moral judgments (Greene et al.
; Borg et al.
), the results are remarkably consistent and revealed a functional network of brain regions including the ventromedial prefrontal cortex (VMPFC), orbitofrontal cortex (OFC), the temporal poles, the amygdala, the posterior cingulate cortex (PCC), and the posterior superior temporal sulcus (PSTS), that is, brain regions which are involved in emotional as well as in cognitive information processing (see Greene and Haidt, 2002
; Casebeer, 2003
; Casebeer and Churchland, 2003
; Moll et al.
, 2005; Goodenough and Prehn, 2004
; Lieberman, 2007
for reviews). Those studies have variously focused on the evaluation of one's own actions and whether actions are intentionally or accidentally (Berthoz et al.
; Berthoz et al.
; Borg et al.
), on the influence of bodily harm on neural correlates of moral decision making (Heekeren et al.
), on the regulation of emotional responses (Harenski and Hamann, 2006
), on the role of cognitive control and conflict processing (Greene et al.
), and on the impact of audience on moral judgments (Finger et al.
). In summary, the results of the previous functional magnetic resonance imaging (fMRI) studies support a theory of moral judgment according to which both emotional and cognitive components
play an important role (Greene et al.
So far, neural correlates of moral decision making have been looked at in group analyses and individual differences in information processing have been treated as ‘noise’. The results of these studies may therefore crucially depend on the specific sample and their characteristics in information processing (Thompson-Schill et al.
; Mériau et al.
A current approach (Lind, 2007
) points out the role of individual differences within the moral domain. Here, morality is defined as consisting of two inseparable, yet distinguishable aspects: (i) a person's moral orientations and principles
and (ii) a person's competence
to act accordingly. According to this theory, moral judgment competence is the ability to apply moral orientations and principles in a consistent and differentiated manner in varying social situations. Thus, social norms and values represented as affectively laden moral orientations are linked by means of moral judgment competence with everyday behavior and decision making. While most people commonly agree upon moral orientations and principles that are considered to be virtuous in their society, it is evident that people differ considerably with respect to their moral judgment competence (Lind, 2007
Thus, relating individual differences in moral judgment competence to brain-imaging data derived from group analyses may lead to a more comprehensive understanding of the neural mechanisms involved in moral judgment. In the present study, we therefore investigated how individual differences in moral judgment competence are reflected in changes in brain activity during a simple socio-normative judgment task. We used event-related fMRI to measure neural activity, while 23 participants made either socio-normative or grammatical judgments and correlated neural activity with individual scores in moral judgment competence.
Based on the previous findings on the neural correlates of moral decision making, we hypothesized that individual differences in moral judgment competence correlate with blood oxygen level-dependent (BOLD) activity in the functional network of brain regions that contribute to moral decision making.