A new meta-analysis just appeared in the Journal of Moral Education on the neural correlates of moral judgment and moral sensitivity in parts of the brain associated with self-hood (full paper available here). Here are some of the key findings:
The default mode network regions were commonly associated with moral functions across diverse domains of moral tasks...The results showed that during [moral] judgment tasks, the ventromedial and dorsomedial prefrontal cortices, temporoparietal junction, middle temporal gyrus and connected superior temporal sulcus, middle occipital gyrus, temporal pole, fusiform gyrus, inferior temporal gyrus and precuneus were activated. In the moral sensitivity condition, the dorsomedial, ventromedial and ventrolateral prefrontal cortices, cingulate gyrus, temporoparietal junction, orbitofrontal cortex, middle temporal gyrus, middle occipital gyrus, fusiform gyrus, lingual gyrus, temporal pole, inferior temporal gyrus, precuneus, cuneus and amygdala were activated.
Allow me to try to parse this out a bit.
The default mode network is an interconnected series of brain regions whose functions include, 'daydreaming and mind-wandering...thinking about others, thinking about [oneself], remembering the past, and planning for the future.' As the author of the meta-analysis notes, the default mode network is known to be systematically involved in representing oneself: it is involved in 'self-evaluation...self-referencing...self-reflection...and episodic and autobiographical memory processing.'
Here is each individual brain region found to be involved in 'moral judgment' (i.e. making decisions in response to moral problems), along with some of each region's known or hypothesized functions (content and quotations taken from hyperlinked material):
Ventromedial Prefrontal Cortex: Emotion regulation. Deficits in this area cause "patients [to] choose alternatives that give immediate rewards, but seem to be blind to the future consequences of their actions.'
Dorsomedial Prefrontal Cortex: "It is involved in creating a sense of the self...[or] "me-ness". It is also involved in what is called "Theory of mind", or considering the mental states of others."
Temperoparietal Junction: involved in empathy with one's own future selves, empathy with other people, and the general 'ability to distinguish different possible perspectives on the same situation' (see here and here).
Middle Occipital Gyrus: contains multiple topographical visual maps of the external world.
Temporal pole: facial recognition and theory of mind (i.e. understanding others' mental states)
Fusiform Gyrus: color information, face & body recognition, word recognition.
Inferior temporal gyrus: visual mapping and object recognition.
Most of these same regions were also found to be involved in 'moral sensitivity' (viz. evaluating the emotional valence of presented moral situations). However, moral sensitivity was also found to involve:
Ventrolateral Prefrontal Cortex: involved in self-control & motor inhibition.
Orbitofrontal cortex: 'important in signaling the expected rewards/punishments of an action given the particular details of a situation.In doing this, the brain is capable of comparing the expected reward/punishment with the actual delivery of reward/punishment, thus, making the OFC critical for adaptive learning.'
Lingual gyrus: '(logical order of events) and encoding visual memories.'
Cuneus: related to inhibition - overstimulation can lead to pathological gambling.
Amygdala: fear, emotional arousal, etc.
In sum, the meta-analysis found that brain regions involved in moral judgment include those concerned with:
- Delaying immediate rewards for possible future rewards. (Ventromedial PFC)
- One's sense of self in relation to others. (Dorsomedial PFC)
- Recognition of a single situation from multiple perspectives (Temporoparietal junction)
- Empathy with one's own future selves and other people. (Temporoparietal junction)
- Theory of mind, or understanding other people's perspectives and mental states (DorsoPFC & temporal pole)
- Contemplating distance from oneself & perspective of other people's visual gaze (MTC, STS)
- Episodic memory of one's past, & reflections upon one's self (precunus)
Moral sensitivity was found to involve these same regions, but also brain regions involved in:
- Self-control & motor inhibition (Ventrolateral PFC)
- Memory formation, including visual memories (Cingulate gyrus & Lingual gyrus)
- Sadness and sense of self-esteem (Cingulate Gyrus)
- Inhibition and gambling avoidance (Cuneus)
- Emotional learning, emotional intelligence, fear and anxiety, etc. (Amygdala)
Here are some addtional related facts:
- Temporopartietal junction (rTPJ):
- Larger rTPJ's are linked to altruism.
- Better interconnected rTPJ's reduce bias for in-groups.
- rTPJ stimulation improves taking other people's perspectives.
- rTPJ inhibition simultaneously diminishes altruism and prudential concern for one's own future selves.
- Some comments on these findings:
- 'For a long time, people have speculated that we use the same mechanisms to reason about other people as about our hypothetical selves...this new study fits really well.'
- "...neuroimaging is notoriously fickle, producing many false positives and false negatives. Yet every group that sought to identify brain regions implicated in ToM got essentially the same answer; and in study after study, we still do.'
- 'Empathy depends on your ability to overcome your own perspective, appreciate someone else’s, and step into their shoes. Self-control is essentially the same skill, except that those other shoes belong to your future self—a removed and hypothetical entity who might as well be a different person. So think of self-control as a kind of temporal selflessness. It’s Present You taking a hit to help out Future You.'
- Psychopaths, who are notable for wantonly violating moral norms and not recognizing the normative force of 'moral reasons', demonstrate (a) impulsivity (Hare 1999), (b) lack of concern for consequences of their past actions (ibid.), (c) lack of concern for future consequences (Hart & Dempster 1997), and (d) underdeveloped brain regions related to 'mental time-travel' (the capacity to imagine possible pasts and futures - Stuss et al. 1992).
- Children and adolescents, commonly recognized as having diminished moral responsibility, display (a) impulsivity (Baumeister et al 2001), (b) inability to think through the future consequences of their actions (ibid.), and (c) underdevelopment in the same brain regions associated with mental time-travel as psychopaths (Casey et al. 2008; Giedd et al 1999; Kennett & Matthews 2009).
- Impulsivity/present-focusedness is one of the strongest individual-level predictors of criminal activity (Van Gelder et al 2013, Hirschi 2004, Gottfredson & Hirschi 1990; and Wilson & Hernstein 1985).
- Self-control (delaying present satisfaction for future reward) is positively related to health, wealth, and success.
- Experimental interventions stimulating future-directed mental time-travel (prompting respondents to imagine the future or interact with a virtual reality depiction of their older self) have been found to simultaneously augment both prudential and moral responses--e.g. saving money for oneself and unwillingness to sell stolen goods (Ersner-Hershfield, Wimmer, & Knutson 2009; Hershfield et al. 2011; Van Gelder et al. 2013).
Readers may note connections to ideas developed here (above citations located therein).