Elsevier

Behavioural Brain Research

Volume 302, 1 April 2016, Pages 237-251
Behavioural Brain Research

Research report
Influence of the cortical midline structures on moral emotion and motivation in moral decision-making

https://doi.org/10.1016/j.bbr.2016.01.001Get rights and content

Highlights

  • The cortical midline structures (CMS) are activated under moral task conditions.

  • The CMS interact with other regions under moral task conditions.

  • Seed regions in the CMS influence the insula under the moral-personal condition.

Abstract

The present study aims to examine the relationship between the cortical midline structures (CMS), which have been regarded to be associated with selfhood, and moral decision making processes at the neural level. Traditional moral psychological studies have suggested the role of moral self as the moderator of moral cognition, so activity of moral self would present at the neural level. The present study examined the interaction between the CMS and other moral-related regions by conducting psycho-physiological interaction analysis of functional images acquired while 16 subjects were solving moral dilemmas. Furthermore, we performed Granger causality analysis to demonstrate the direction of influences between activities in the regions in moral decision-making. We first demonstrate there are significant positive interactions between two central CMS seed regions—i.e., the medial prefrontal cortex (MPFC) and posterior cingulate cortex (PCC)—and brain regions associated with moral functioning including the cerebellum, brainstem, midbrain, dorsolateral prefrontal cortex, orbitofrontal cortex and anterior insula (AI); on the other hand, the posterior insula (PI) showed significant negative interaction with the seed regions. Second, several significant Granger causality was found from CMS to insula regions particularly under the moral-personal condition. Furthermore, significant dominant influence from the AI to PI was reported. Moral psychological implications of these findings are discussed. The present study demonstrated the significant interaction and influence between the CMS and morality-related regions while subject were solving moral dilemmas. Given that, activity in the CMS is significantly involved in human moral functioning.

Introduction

Contemporary moral psychologists have studied the integrative model of human morality that can well explain the mechanism of moral motivation and actual moral behavior. Before the beginning of the 21st century, the mainstream paradigm in moral psychology was the Kohlbergian model, which attempted to explain the generation of moral behavioral motivation from a cognitive vantage point [1], [2]. However, this model has been criticized by proponents of the role of moral emotion [3] and intuition [4], [5]; those scholars have argued that the previous model was not able to successfully bridge the gap between moral reasoning and moral behavior [6]. Thus, to address this issue, contemporary moral psychologists have proposed an integrative model of human morality, which embraces the cognitive, affective and behavioral aspects. For instance, Neo-Kohlbergians, the contemporary moral psychologists who proposed integrative model of moral functioning (e.g., [7], [8], [9]), suggested the functional components of moral sensibility, moral motivation and moral personality on top of moral judgment [7]. In addition, character educators, who have sought to develop a new model of moral psychology that is suitable to educational practice, have underscored the integration of moral cognition, emotion and behavior [10], [11].

Then, what is the core or foundation of the integrative model? Which psychological construct does orchestrates activity of individual aspects of human morality and regulate the generation of motivational force for moral behavior? Several moral psychologists have suggested moral self as a candidate [12], [13], [14]. According to their theory, moral self is a psychological construct constituted by the perception of a person’s self as a moral person, which originates from moral identity [15]. Although a person might have developed sophisticated moral reasoning, he/she does not necessarily implement the result of his/her moral judgment into action if he/she does not possess a strong sense of moral self because he/she does not prioritize moral values over other self-oriented values [13], [16]. In fact, social psychological experiments have confirmed that the strength of moral self significantly moderated the relationship between the result of moral judgment [17], [18], perceived socio-moral emotional valence [19] and actual moral behavioral outcome. The formation and development of moral self occurs through reflection upon and deliberation of beliefs, values and previous life experience, and continued commitment to moral behavior [20]. During adolescence and even beyond, a person’s moral self is being consolidated by integrating moral values into his/her self-identity [14], [21].

Neuroimaging methods will facilitate this kind of research investigating the nature of human morality [22], [23]. Neuroimaging studies have contributed significantly to our understanding of human morality because they enable us to investigate the internal processes of moral functions that underlie overt human behaviors, which have not been measured by non-biological traditional methodologies [23], [24]. These studies also aim to avoid the potential social and desirable biases of self-reporting methods that have been problematic in traditional moral psychological studies [22].

Based on the previous studies, the present study aims to examine the relationship between the cortical midline structures (CMS), which have been regarded to be associated with selfhood, and moral decision making processes at the neural level. Previous fMRI studies in the field of cognitive and social neurosciences have examined the neural correlates of human morality. For instance, diverse dimensions of morality including, but not limited to, moral judgment [25], [26], moral sensibility [27], [28], [29], moral competence [30] and moral elevation [31], [32] have been demonstrated. Furthermore, several social neuroscientists have proposed the presence of the co-activation of selfhood-related regions, particularly those in the cortical midline structures (CMS) during the processing of moral tasks. The CMS include the dorsal- and ventral-medial prefrontal cortices (MPFC) and cingulate cortex [33], [34]. Recent meta-analyses [35], [36] and fMRI studies [37], [38] have also demonstrated that the processing of self-related and familiar contexts is associated with activity in the CMS regions, including the MPFC, PCC and anterior cingulate cortex (ACC). However, some studies have shown that in certain instances, activity in the posterior medial cortices (PMC) in the CMS was not stronger in “self” conditions compared to “others” conditions; more specifically, the region showed significantly stronger activity in the distant-others condition compared to the self condition in general [36], [37]. Given these studies, it would be possible to say that the MPFC is commonly associated with selfhood-related processes, but the PMC is particularly associated with autobiographical memory processing rather than selfhood-related processes in general [37]. In studies related to morality, neuroimaging studies have also shown the relationship between the CMS regions and morality-related task conditions. In the previous fMRI studies, activity in the CMS regions was commonly associated with moral task conditions [39], [40], [41]. In addition, self-agency related to moral functioning shared neural substrates with the CMS [42]. Given these previous studies, we expect that there is significant relationship between the neural correlates of moral functioning and selfhood-related processes. The present study uses the general linear model (GLM) method to conduct the whole-brain tests; this method enables us to conduct “a diverse interrogation of functional imaging data using statistical parametric maps (p. 202)” and a diverse statistical analysis from a t-test to ANCOVA [43].

Given these studies in social neuroscience demonstrating the activation of the CMS regions in morality-related task conditions, we can expect a significant overlap between the brain circuitries associated with moral functioning and selfhood-related psychological processes. Moreover, the nature of moral dilemmas would cause increased activity in such regions compared to non-moral dilemmas. Usually, moral dilemmas are regarded as problem sets that deal directly with “what we have to do” or “what we ought to do,” while non-moral dilemmas are in the realm of fact, instead of value [44]. Particularly, moral-personal dilemmas (e.g., Footbridge dilemma) are closely associated with the possible violation to concrete human lives; on the other hand, moral-impersonal dilemmas (e.g., Trolley dilemma) do not directly request subjects to make decisions affecting concrete human lives, but are similar to mathematical calculation problems [25], [26], [45]. Since moral dilemmas are more likely to urge us to deliberate upon our moral beliefs and values, they would induce stronger activity in the CMS regions compared to non-moral dilemmas.

Furthermore, although traditional moral psychologists did not use neuroimaging methods, their social psychological [13], [17], [18], [46] and developmental psychological studies [14], [20] have shown the moderating and monitoring role of moral self in moral functioning. Thus, we may also expect that brain activity in the CMS associated with selfhood moderates or even influences that in other regions associated with moral functioning. However, the previous studies that have shown the overlap between those two brain circuitries did not utilize analytic methods that enable us to see the interaction between or causal relationship between brain regions, such as the psycho-physiological interaction (PPI) analysis [47] and Granger causality analysis [48]. The problem of reverse inference occurs if we try to interpret findings without the application of proper experimental and analysis methods [49], [50]. Therefore, the present study aims to investigate such possible moderating and causal relationship between the CMS and other regions associated with moral functioning in morality-related task conditions, using the PPI analysis and GCA methods when subjects are making moral decisions to address moral problems.

The present study hypothesizes that first, the whole-brain tests will demonstrate that brain regions associated with emotional processes will show greater activity in the moral-personal condition compared to the moral-impersonal condition. This hypothesis originates from previous neuroimaging studies utilizing similar dilemma task conditions [25], [26], [51]. Moral-personal dilemmas are more likely to induce significant activity in regions associated with emotion (e.g., MPFC, orbitofrontal cortex (OFC), superior-temporal sulcus (STS), insula [42], [51], [52], [53], [54], [55]) compared to moral-impersonal dilemmas, because the former strongly induce negative immediate emotional responses among subjects. On the other hand, previous studies have shown that in the moral-impersonal condition, regions associated with cognition, such as mental calculation (e.g., parietal lobule), will show significantly increased activity [25], [26], [51], [56].

Second, activity in the CMS regions significantly moderates activity in other brain regions associated with moral emotion and motivation (e.g., midbrain including the ventral tegmental area, ventral striatum, insula, OFC [57], [58], [59], [60], [61]) while subjects are solving moral problems. Given previous neuroimaging studies showing the overlap between the two regions, and traditional moral psychological studies suggesting the role of moral self, the present study will be able to find significant PPI between CMS and other regions associated with morality in the moral-task condition. Particularly, the present study focuses on the MPFC and posterior cingulate cortex (PPC) in the CMS. First, the MPFC is associated with self-referencing and self-evaluation [62], [63], [64], which are fundamental to moral decision making processes. These selfhood-related psychological processes enable people to consider and reflect upon their moral belief and value and to make a decision based on them [14], [20], [65]; moral decision making also would be moderated by these processes. Second, the present study also focuses on the PCC, because this region is associated with the processing of autobiographical memory, including self-referencing [33], [37], [66], [67], [68], [69]. Of course, although the PCC would not be strongly associated with selfhood-related processes in general, because this region is associated with the autobiographical memory processing [36], [37], the core self-related process involved in moral decision making, the present uses this region as a seed region. Because moral judgment cannot be independent from and is influenced by the deliberation upon previous lifelong experience [14], [20], [70], autobiographical memory processes inevitably would be involved in moral judgment, as the proponents of moral self and moral identity suggest [71], [72]. Given these, the present study focuses on the MPFC and PPC, which are closely associated with selfhood-related psychological processes.

Third, given the role of moral self proposed by traditional moral psychologists, the present study expects causal influence from activity in the CMS to that in other brain regions associated with moral emotion and motivation. The GCA will demonstrate significant causal influence from the MPFC and PPC to brain regions associated with moral emotion and motivation. More specifically, among all brain regions associated with morality, the present study concentrates on the insula regions, including both the anterior (AI) and posterior insula (AI). First, previous experiments have demonstrated that the PI is the core of the immediate processing of affective responses and the induction of subjective feelings [73], [74], particularly negative emotions (e.g., pain and disgust) [73], [74], [75], [76], [77], that play fundamental roles in moral cognition [42], [53]. Moreover, the AI is closely associated with the integration of cognition and emotion [78], [79], [80], [81], [82], conscious and interceptive awareness, monitoring of aroused emotional responses [28], [83], [84], and finally, the modulation of motivational force [60], [61], [85]. Given these previous works, the present study chooses the AI and PI as the regions of interest for the GCA.

Section snippets

Subjects

The present study recruited sixteen subjects at a college located in Northern California, using university mailing lists and Facebook. Only healthy right-handed subjects were included to control for any possible compounding effect originated from a history of physical or mental illness and handedness. Subjects' physical and mental health condition (e.g., allergies, kidney problems, seizures, claustrophobia) was tested using a standard self-reporting questionnaire developed by The Richard M.

Whole brain analyses

We conducted whole-brain t-tests to examine whether the present experiment replicated well previous studies that used a similar dilemma set. Two contrasts (i.e., moral-personal versus control and moral-impersonal versus control) applied to the analyses. Furthermore, we also compared brain activity between those two dilemma types. The results are summarized in Table S2 and displayed in Fig. 2. These results demonstrated that the MPFC and ACC showed significantly great activity under the

Discussion

First, the present study compared the neural-level activity under the moral-personal, moral-impersonal and control conditions through whole-brain t-tests. The comparison showed that the MPFC was particularly activated under the moral-personal condition, while the parietal lobule regions were significantly activated under the moral-impersonal condition. These whole-brain t-tests successfully replicated previous fMRI investigations that utilized similar moral dilemmas [25], [26], [51]. Second, we

Conclusion

The present study demonstrates significant interactions developed between the CMS (PCC and MPFC) and other moral-related regions including AI and PI while subjects are solving moral dilemmas. These results can support the moral psychological accounts regarding the role of moral self in moral decision-making processes. Particularly, motivational processes for moral decision-making is coupled with activity in CMS regions, which is regarded as an indicator of the involvement of selfhood-related

Disclosure

The authors report no conflicts of interest.

References (151)

  • R.A. Poldrack

    Can cognitive processes be inferred from neuroimaging data?

    Trends Cogn. Sci.

    (2006)
  • H. Han et al.

    Cultural influences on the neural correlate of moral decision making processes

    Behav. Brain Res.

    (2014)
  • C.L. Harenski et al.

    Neural correlates of regulating negative emotions related to moral violations

    Neuroimage

    (2006)
  • H. Takahashi et al.

    Brain activation associated with evaluative processes of guilt and embarrassment: an fMRI study

    Neuroimage

    (2004)
  • R.J. Maddock et al.

    Remembering familiar people: the posterior cingulate cortex and autobiographical memory retrieval

    Neuroscience

    (2001)
  • E. Svoboda et al.

    The functional neuroanatomy of autobiographical memory: a meta-analysis

    Neuropsychologia

    (2006)
  • J. Isnard et al.

    Does the insula tell our brain that we are in pain?

    Pain

    (2011)
  • N.H. Naqvi et al.

    The hidden island of addiction: the insula

    Trends Neurosci.

    (2009)
  • T. Straube et al.

    Attention to aversive emotion and specific activation of the right insula and right somatosensory cortex

    Neuroimage

    (2011)
  • A.D.B. Craig

    Human feelings: why are some more aware than others?

    Trends Cogn. Sci.

    (2004)
  • C. Chang et al.

    Relationship between respiration, end-tidal CO2, and BOLD signals in resting-state fMRI

    Neuroimage

    (2009)
  • C.R. Genovese et al.

    Thresholding of statistical maps in functional neuroimaging using the false discovery rate

    Neuroimage

    (2002)
  • L. Barnett et al.

    The MVGC multivariate Granger causality toolbox: a new approach to Granger-causal inference

    J. Neurosci. Methods

    (2014)
  • A.K. Seth

    A MATLAB toolbox for Granger causal connectivity analysis

    J. Neurosci. Methods

    (2010)
  • L. Kohlberg

    The Philosophy of Moral Development: Moral Stages and the Idea of Justice

    (1981)
  • L. Kohlberg

    The Psychology of Moral Development: The Nature and Validity of Moral Stages

    (1984)
  • M.L. Hoffman

    Empathy and Moral Development: Implications for Caring and Justice

    (2000)
  • J. Haidt

    The emotional dog and its rational tail: a social intuitionist approach to moral judgment

    Psychol. Rev.

    (2001)
  • J.R. Rest et al.

    Postconventional Moral Thinking: A Neo-Kohlbergian Approach

    (1999)
  • J.R. Rest et al.

    Moral Development in the Professions: Psychology and Applied Ethics

    (1994)
  • S.J. Thoma et al.

    The relationship between moral decision making and patterns of consolidation and transition in moral judgment development

    Dev. Psychol.

    (1999)
  • M.J. Bebeau

    The defining issues test and the four component model: contributions to professional education

    J. Moral Educ.

    (2002)
  • T. Lickona

    Eleven principles of effective character education

    J. Moral Educ.

    (1996)
  • M.W. Berkowitz et al.

    Early character development and education

    Early Educ. Dev.

    (2000)
  • S.A. Hardy et al.

    Identity as a source of moral motivation

    Hum. Dev.

    (2005)
  • A. Blasi

    Moral identity: its role in moral functioning

  • W. Damon

    Self-understanding and moral development from childhood to adolescence

  • J.E. Stets et al.

    The moral self: applying identity theory

    Soc. Psychol. Q.

    (2011)
  • A. Blasi

    Moral character: a psychological approach

  • A. Reed et al.

    Moral identity and judgments of charitable behaviors

    J. Mark.

    (2007)
  • K. Aquino et al.

    The self-importance of moral identity

    J. Personal. Soc. Psychol.

    (2002)
  • P. Conway et al.

    When does feeling moral actually make you a better person? Conceptual abstraction moderates whether past moral deeds motivate consistency or compensatory behavior

    Personal. Soc. Psychol. Bull.

    (2012)
  • A. Colby et al.

    Some Do Care: Contemporary Lives of Moral Commitment

    (1992)
  • A. Colby et al.

    The uniting of self and morality in the development of extraordinary moral commitment

  • T.A. Ito et al.

    Attitudes as mental and neural states of readiness: using physiological measures to study implicit attitudes

  • K. Kristjánsson

    Measuring self-respect

    J. Theory Soc. Behav.

    (2007)
  • K. Kristjánsson

    Virtues and Vices in Positive Psychology: A Philosophical Critique

    (2013)
  • J.D. Greene et al.

    An fMRI investigation of emotional engagement in moral judgment

    Science

    (2001)
  • J. Decety et al.

    The contribution of emotion and cognition to moral sensitivity: a neurodevelopmental study

    Cereb. Cortex

    (2012)
  • J. Moll et al.

    The neural correlates of moral sensitivity: a functional magnetic resonance imaging investigation of basic and moral emotions

    J. Neurosci.

    (2002)
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