Disgust


Disgust is an emotional response of rejection or revulsion to something potentially contagious or something considered offensive, distasteful or unpleasant. In The Expression of the Emotions in Man and Animals, Charles Darwin wrote that disgust is a sensation that refers to something revolting. Disgust is experienced primarily in relation to the sense of taste, and secondarily to anything which causes a similar feeling by sense of smell, touch, or vision. Musically sensitive people may even be disgusted by the cacophony of inharmonious sounds. Research has continually proven a relationship between disgust and anxiety disorders such as arachnophobia, blood-injection-injury type phobias, and contamination fear related obsessive–compulsive disorder.
Disgust is one of the basic emotions of Robert Plutchik's theory of emotions, and has been studied extensively by Paul Rozin. It invokes a characteristic facial expression, one of Paul Ekman's six universal facial expressions of emotion. Unlike the emotions of fear, anger, and sadness, disgust is associated with a decrease in heart rate and proto-nausea of the stomach.

Evolutionary significance

It is believed that the emotion of disgust has evolved as a response to offensive foods that may cause harm to the organism. A common example of this is found in human beings who show disgust reactions to mouldy milk or contaminated meat. Disgust appears to be triggered by objects or people who possess attributes that signify disease.
Self-report and behavioural studies found that disgust elicitors include:
  • body products ;
  • foods ;
  • animals ;
  • hygiene ;
  • body envelope violations ;
  • death ;
  • visible signs of infection
The above-mentioned main disgust stimuli are similar to one another in the sense that they can all potentially transmit infections, and are the most common referenced elicitors of disgust cross-culturally. Because of this, disgust is believed to have evolved as a component of a behavioral immune system in which the body attempts to avoid disease-carrying pathogens in preference to fighting them after they have entered the body. This behavioral immune system has been found to make sweeping generalizations because "it is more costly to perceive a sick person as healthy than to perceive a healthy person as sick". Researchers have found that sensitivity to disgust is negatively correlated to aggression because feelings of disgust typically bring about a need to withdraw while aggression results in a need to approach. This can be explained in terms of each of the types of disgust. For those especially sensitive to moral disgust, they would want to be less aggressive because they want to avoid hurting others. Those especially sensitive to pathogen disgust might be motivated by a desire to avoid the possibility of an open wound on the victim of the aggression. Those sensitive to sexual disgust must have some sexual object present to be especially avoidant of aggression. Based on these findings, disgust may be used as an emotional tool to decrease aggression in individuals. Disgust may produce specific autonomic responses, such as reduced blood pressure, lowered heart-rate and decreased skin conductance along with changes in respiratory behaviour.
Research has also found that people who are more sensitive to disgust tend to find their own in-group more attractive and tend to have more negative attitudes toward other groups. This may be explained by assuming that people begin to associate outsiders and foreigners with disease and danger while simultaneously associating health, freedom from disease, and safety with people similar to themselves.
Taking a further look into hygiene, disgust was the strongest predictor of negative attitudes toward obese individuals. A disgust reaction to obese individuals was also connected with views of moral values.

Domains of disgust

Tybur, et al., outlines three domains of disgust: pathogen disgust, which "motivates the avoidance of infectious microorganisms"; sexual disgust, "which motivates the avoidance of sexual partners and behaviors"; and moral disgust, which motivates people to avoid breaking social norms. Disgust may have an important role in certain forms of morality.
Pathogen disgust arises from a desire to survive and, ultimately, a fear of death. He compares it to a "behavioral immune system" that is the 'first line of defense' against potentially deadly agents such as dead bodies, rotting food, and vomit.
Sexual disgust arises from a desire to avoid "biologically costly mates" and a consideration of the consequences of certain reproductive choices. The two primary considerations are intrinsic quality and genetic compatibility.
Moral disgust "pertains to social transgressions" and may include behaviors such as lying, theft, murder, and rape. Unlike the other two domains, moral disgust "motivates avoidance of social relationships with norm-violating individuals" because those relationships threaten group cohesion.

Gender differences

Women generally report greater disgust than men, especially regarding sexual disgust or general repulsiveness which have been argued to be consistent with women being more selective regarding sex for evolutionary reasons.
Sensitivity to disgust rises during pregnancy, along with levels of the hormone progesterone. Scientists have conjectured that pregnancy requires the mother to "dial down" her immune system so that the developing embryo won't be attacked. To protect the mother, this lowered immune system is then compensated by a heightened sense of disgust.
Because disgust is an emotion with physical responses to undesirable or dirty situations, studies have proven there are cardiovascular and respiratory changes while experiencing the emotion of disgust.
As mentioned earlier, women experience disgust more prominently than men. This is reflected in a study about dental phobia. A dental phobia comes from experiencing disgust when thinking about the dentist and all that entails. 4.6 percent of women compared to 2.7 percent of men find the dentist disgusting.

Non-verbal communication

In a series of significant studies by Paul Ekman in the 1970s, it was discovered that facial expressions of emotion are not culturally determined, but universal across human cultures and thus likely to be biological in origin. The facial expression of disgust was found to be one of these facial expressions. This characteristic facial expression includes slightly narrowed brows, a curled upper lip, wrinkling of the nose and visible protrusions of the tongue, although different elicitors may produce different forms of this expression. It was found that the facial expression of disgust is readily recognizable across cultures. This facial expression is also produced in blind individuals and is correctly interpreted by deaf individuals. This evidence indicates an innate biological basis for the expression and recognition of disgust. The recognition of disgust is also important among species as it has been found that when an individual sees a conspecific looking disgusted after tasting a particular food, he or she automatically infers that the food is bad and should not be eaten. This evidence suggests that disgust is experienced and recognized almost universally and strongly implicates its evolutionary significance.
Facial feedback has also been implicated in the expression of disgust. That is, the making of the facial expression of disgust leads to an increased feeling of disgust. This can occur if the person just wrinkles one's nose without awareness that they are making a disgust expression.
The mirror-neuron matching system found in monkeys and humans is a proposed explanation for such recognition, and shows that our internal representation of actions is triggered during the observation of another's actions. It has been demonstrated that a similar mechanism may apply to emotions. Seeing someone else's facial emotional expressions triggers the neural activity that would relate to our own experience of the same emotion. This points to the universality, as well as survival value of the emotion of disgust.

Children's reactions to a face showing disgust

At a very young age, children are able to identify different, basic facial emotions. If a parent makes a negative face and a positive emotional face toward two different toys, a child as young as five months would avoid the toy associated with a negative face. Young children tend to associate a face showing disgust with anger instead of being able to identify the difference. Adults can make the distinction. The age of understanding seems to be around ten years old.

Cultural differences

Because disgust is partially a result of social conditioning, there are differences among different cultures in the objects of disgust. For example, Americans "are more likely to link feelings of disgust to actions that limit a person's rights or degrade a person's dignity" while Japanese people "are more likely to link feelings of disgust to actions that frustrate their integration into the social world." Furthermore, practices viewed as acceptable in some cultures may be viewed as disgusting in other cultures. In English, the concept of disgust can apply to both physical and abstract things, but in Hindi and Malayalam languages, the concept does not apply to both.
Disgust is one of the basic emotions recognizable across multiple cultures and is a response to something revolting, typically involving taste or sight. Though different cultures find different things disgusting, the reaction to the grotesque things remains the same throughout each culture; people and their emotional reactions in the realm of disgust remain the same.

Neural basis

The scientific attempts to map specific emotions onto underlying neural substrates dates back to the first half of the 20th century.
Functional MRI experiments have revealed that the anterior insula in the brain is particularly active when experiencing disgust, when being exposed to offensive tastes, and when viewing facial expressions of disgust. The research has supported that there are independent neural systems in the brain, each handling a specific basic emotion. Specifically, f-MRI studies have provided evidence for the activation of the insula in disgust recognition, as well as visceral changes in disgust reactions such as the feeling of nausea. The importance of disgust recognition and the visceral reaction of "feeling disgusted" is evident when considering the survival of organisms, and the evolutionary benefit of avoiding contamination.