Moral Cognition & Disgust

In this section, I first review theories of moral cognition and moral emotions (Section 2.4.1), and then I describe theories proposing a unique link between physical and moral disgust (Section 2.4.2).

Furthermore, this section shows how issues of morality can be investigated empirically, and presents the different theoretical accounts for moral processing in the brain.

2.4.1 Theories of moral cognition and their treatment to moral emotions

The extent to which an action is right or wrong, i.e. morality, is widely used to guide human behavior.

It provides humans a valuable tool when judging their own or others’ behavior. These moral decisions are typically driven by beliefs and values⁴⁴⁵ instilled in us from various agents, e.g., our parents, schools, and religious institutions. Acts that are considered immoral are condemned and punished, reinforcing these beliefs.

The last few years have seen a proliferation of research investigating moral cognition and, specifically, the degree to which our evaluation of others’ conducts can be affected by current perceptual and emotional states. In experimental psychology and neuroscience, moral judgments have often been investigated through the use of moral dilemmas. Such dilemmas describe an individual confronted with the choice of whether or not to violate a moral norm (e.g., kill someone), to maximize community welfare (e.g., the life sacrificed will save five others). Individuals often consider it inappropriate to act in the most utilitarian fashion, especially if it leads to personally inflicting harm on others⁴⁴⁶. To elucidate the cognitive mechanisms underlying moral decision-making, meta-analytic data of neuroimaging studies report on an extensive network of brain areas - “the moral brain” - to be involved in moral decision making^447–452. This extensive network includes: the dorsolateral, dorsomedial and anterior portion of the prefrontal cortex, the superior temporal sulcus, the orbitofrontal cortex, the ventromedial prefrontal cortex, insula, amygdala/hippocampal formation, striatum, and the anterior and posterior cingulate gyri^447–452.

One of the most influencing theories aiming better to explain the integration of those brain areas in moral decision making is the “Dual-Process Theory” by Greene and colleagues446,453–455 (Figure 9). The theory associated utilitarian moral judgment (approving of harmful actions that maximize good consequences) with cognitive-control processes and related non-utilitarian moral judgment (favoring individual’s rights) with intuitive, emotional responses [for an overview see⁴⁴⁹]. The "Dual-Process Theory" is focused on the role of cognitive control in moral judgment. It assumes that cognitive control processes (afforded by the lateral PFC and ACC), override emotional responses (attributed to the medial PFC, posterior cingulate cortex, and STS) to produce utilitarian responses to moral dilemmas.

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It also assumes that emotional-processing areas would favor personal (compared to impersonal or non-moral) judgments.

Specifically, the "Dual-Process Theory” postulates that the dorsolateral prefrontal cortex (DLPFC) and the ventromedial prefrontal cortex (VMPFC) are key players in moral decisions which involve judgments. Engaging in non-utilitarian moral-reasoning evokes a negative emotional response (associated with VMPFC activity) that drives moral disapproval. However, engaging in utilitarian moral reasoning result in a cost–benefit analysis (associated with DLPFC activity) that drives moral approval^446,453. Importantly, when there is no dominant emotional response, judgments are driven by utilitarian reasoning, but when dilemmas evoke a strong negative emotional response, they can lead to a conflict between emotions and utilitarian reasoning. This conflict is detected by the anterior cingulate cortex (ACC) which signals the need for cognitive control and therefore recruits the DLPFC.

If the emotional response does not reach a certain “threshold,” the cognitive reasoning can overcome the initial emotional response. Therefore, increased activity in the DLPFC would be observed in difficult (i.e. higher than the “emotional response threshold”) utilitarian moral judgments^453,456. In support of the dual-process theory, neuroimaging studies have shown that the DLPFC mediates cognitive-control processes in utilitarian moral judgments and the VMPFC mediates emotional processing in non-utilitarian moral-judgments. Comparing impersonal dilemmas (a utilitarian judgment with weak emotional engagement) with personal dilemmas resulted with increased neural activity in the DLPFC and the inferior temporal lobe446,457,458. This finding is consistent with extensive research suggesting a critical involvement of the DLPFC in cognitive control and working memory processes⁴⁵⁹. In contrast, personal moral dilemmas (a non-utilitarian judgment with strong emotional engagement) evoked moral-related emotions and were associated with increased activations in brain areas involved in emotional processing such as the VMPFC, posterior cingulate cortex (PCC), superior temporal sulcus (STS), the temporoparietal junction (TPJ)^446,457 and the amygdala⁴⁵³. Particularly, the VMPFC involvement in processing moral-emotions was observed in comparisons of moral with non-moral dilemmas⁴⁶⁰, moral vs. non-moral visual scenes⁴⁶¹, difficult vs. easy personal moral judgments⁴⁵³. Moreover, the VMPFC has been shown to work in concert with the amygdala in the processing of emotions^462,463. In sum, Green’s “dual-process” theory posits mutually competitive roles of cognition and emotion in moral judgment.

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Figure 9 - The Dual Process Theory of Moral Judgement.

Taken from⁴⁴⁹.

However, Greene’s clear-cut distinction between the influences of cognition and emotion in moral judgments is not accepted by all. One of the most renown competing theories is the “Event–feature–

emotion complex (EFEC) framework” by Jorge Moll^447,448. Accordingly, the EFEC framework postulates that moral cognitive and behavioral phenomena arise from the binding of three principal components (Figure 10): structured event knowledge (provided by context-dependent representations in prefrontal subregions), social perceptual and functional features (stored in the posterior and anterior sectors of the temporal cortex), and central motive or basic emotional states (such as aggressiveness, sadness, attachment or sexual arousal, represented in limbic and paralimbic regions). Moll’s theory provides a framework for better understanding moral emotions (e.g. guilt, pity, embarrassment, shame, pride, awe, contempt, indignation, anger, moral disgust, and gratitude)⁴⁶⁴. Moral Emotions are emotions that are linked to the interest or welfare of other people or society as a whole, and function to guide moral judgments by allocating values to choices that are contemplated during the tackling of a moral dilemma^447,448. They result from interactions among values, norms and contextual elements of social situations, and are elicited in response to violations or enforcement of social preferences and expectations^465–467. In contrast to Green’s process approach, the EFEC framework is a representational approach to understanding the neural basis of moral emotions. In this view, the elicitation of moral emotions is carried out by dynamic prefrontal cortex-temporo-limbic network representations, which

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arise from the activation of one or more of the following six components: attachment, aggressiveness, social rank, outcome assessment, agency, and norm violation^447,448.

Figure 10 – The Event-Feature-Emotion Complex (EFEC) Framework.

Taken from⁴⁴⁷.

Finally, different from the previous accounts of Green and Moll, another perspective suggests that disgust has a major and specific role in moral cognition, as an embodied moral judgement^468–470. For instance, in a series of experiments conducted by Schnall and colleagues⁴⁶⁸, participants made moral judgments while experiencing extraneous feelings of disgust (exposure to a bad smell, working in a disgusting room, recalling a disgusting situation, and through video induction). In all experiments, the data showed that disgust can increase the severity of moral judgments (relative to controls and sadness induction)⁴⁶⁸. This perspective relates to previous theories of disgust, according to which part of the disgusting experience is of moral nature (“moral disgust”), and can be triggered by the violation of social norms or moral values^145,146. In this case, moral disgust may be motivating the avoidance of individuals who violate social norms, who accordingly may not be good partners for interaction¹⁴⁵. 2.4.2 The link between moral and physical disgust

Indeed, there is evidence that moral disgust is a genuine form of disgust, which has an associative link with physical disgust. First, both adults and children call moral transgressions disgusting^471–473 and

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match them to disgusted facial expressions^473–475 even when the transgressions do not reference physical disgust. Second, moral transgressions result in a canonical facial expression^475,476, similar to that elicited by physical disgust and distaste⁴⁷⁵. Specifically, the upper lip raise in response to transgressions was found to be correlated with self-reported disgust, but not with other emotions (e.g. anger or contempt)⁴⁷⁵. Third, individuals with high (compared to those with low) sensitivity to physical disgust make more severe judgments about moral transgressions, an effect which is not accounted by other differences in negative traits⁴⁷⁷. Finally, it has been shown that inducing physical disgust or distaste can affect people’s moral evaluations, and vice versa468,478,479. For instance, participants made harsher moral judgments when subjected to a disgusting odor⁴⁶⁸ or a bitter taste⁴⁷⁹. Likewise, people find drinks more unpleasant after having observed immoral (as opposed to moral) behaviors⁴⁸⁰. Moreover, Wheatley and Haidt have reported that participants made harsher moral judgments following an induction of disgust feeling by hypnosis⁴⁷⁸.

In addition to behavioral data, neuroimaging studies also support the idea of a specific link between physical disgust and moral disgust. Comparisons between vignettes describing disgusting situations devoid of moral connotations (e.g. “one night you were walking on a street. You saw a cat eating its excrement”) with those describing moral disgusting situations (e.g. incest specific stories) during moral judgments rendered in overlapping activations in several disgust-associated brain areas (e.g., insula, ACC, piriform cortex)^447,481, thus providing hints of shared neural mechanisms underlying the two experiences. It is still unknown, however, whether the observed biases in moral judgments are uniquely mediated by brain areas associated with disgust processing or, by a more general processing of aversive experiences such as pain.

Importantly, several concerns have also been raised about studies of moral disgust^159,482. For example, it seems that moral disgust is relatively insensitive to the offender intent and the degree of harm resulting from a transgression^483,484, factors that are considered to be important in moral reasoning.

Also, experimentally-induced disgust and individual differences in disgust-sensitivity could also have a strong influence on moral judgments of dilemmas containing reminders of physical disgust stimuli, such as sexually immoral behavior (relative to dilemmas without those reminders)⁴⁸⁵. Furthermore, there are also concerns related to measurements. Self-reports of moral disgust are quite sensitive to how questionnaire measures are phrased^162,472. Similarly, different studies use quite dramatically different “moral” stimuli, which could have distinct relationships to moral disgust. Finally, although previous evidence shows that moral transgressions can induce disgust response in a similar fashion to physical disgust, other views do not consider moral disgust a unique class of disgust, but rather a compelling metaphor used to condemn antisocial behavior^482,486.

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