The sample of subjects were given a questionnaire on disgust that contained items to elicit disgust. Statistical analysis was performed on the items and on the scores via a synthetic indicator, the Synthetic Disgust Index SDI. The analysis revealed a different trend in different types of disgust for age and sex. In males. Darwin defined disgust as a primary emotion referred to something revolting, in relation to the sense of taste, as actually perceived or vividly imagined Darwin, In addition, the concept of disgust can be expanded to involve violation of body borders at points other than the mouth Rozin, Fallon, This concept of disgust can be further elaborated to include: human-animal origin disgust; interpersonal contamination; aggressivity and moral disgust such as sexual aspects.
From an evolutionary perspective, disgust is seen as a difensive mechanism protecting the organism from contamination by pathogens. The prevalence of disgust in females and sensitivity to it have also been studied in relation to phobias, above all ones relating to blood, injections and wounds. Both female gender and sensitivity to disgust are positive predictors of phobias. Disgust literally- bad taste has been defined in terms of a food related emotion.
The prototypical objects of disgust have been identified as waste products of the human and animal body but extend to biological substances such as blood, saliva, sweat and hair. Disgust centres around the holes in the body Rozin et al. Most of the disgusting body products e. Various studies have linked physical disgust to moral disgust. In common parlance moral transgressions "leave a bad taste in the mouth" implies a link between moral disgust and more primitive forms of disgust related to toxicity and disease.
Moral disgust operates to protect and preserve social order, and historically, has been largely shaped by religious and legal institutions. These variables are disgusting stimuli influenced by culture and individual differences.
Numerous studies have highlighted the prevalence of the feeling of disgust in females. In their study on individual differences in sensitivity to disgust, Haidt, McCauley and Rozin underline that the best predictor of sensitivity to disgust is gender.
Substantially differences emerged for the domains of body products, animals and while they were smaller in the domains of hygiene and sex. In the same study, sensitivity to disgust was correlated with specific personality traits linked to this emotion as a defence. Other authors have confirmed this finding. Druschel and Sherman also identified variables that affect sensitivity to disgust in both females and in personality traits, supporting the theory that there are dimensions of a normal adult personality that are linked to this sensitivity.
The findings relating to gender in this study were consistent with previous research and it emerged that sensitivity to disgust is present in certain characteristics, namely neuroticism and conscientiousness, demonstrating that the reaction to a disgust stimulus rather than being a defence against a biological threat is, instead, the product of socio-cultural conditioning and psychological functioning.
A study by Chentsova-Dutton and Tsai which analysed the biological gender and social ethnic differences of primary and secondary emotions showed that women manifest more evident emotional behaviours than men. However, this gender difference was not found to be significant for some emotions, disgust among them.
Emotions do not differ between different ethnic groups, because the social roles of men and women are unaltered in the various groups. Collignon et al. The results showed women to be better able to recognize and express emotions. On the basis of these observations, we decided to investigate gender differences regarding this feeling of disgust in its various dimensions, viewed both individually and globally. A sample of subjects was taken from the town of Messina males and females.
Subjects were contacted by medicine students of Messina University Hospital, who asked relatives and neighbors to voluntarily answer the questionnaire.
We excluded from the study 71 people who did not answer to gender and age. More details of the demographic features of the sample are presented in Table 1.
Subjects were asked to complete a questionnaire on disgust. The disgust scale is a measuring instrument of degree of reaction to disgust when evoked by mental images that potentially elicit it, the items were created from the theoretical construct of Miller's work The original questionnaire included questions of a general nature about age, gender, education, the type of food and smells that respondents found disgusting and 50 questionnaire items in the form of statements.
For each of these, subjects were instructed to indicate to what extent they agreed or disagreed by assigning a score from 1 to Each item was designed to evoke mental images eliciting disgust: e. Of the overall items scale, the internal consistency as reflected in Cronbach's alpha was 0. Test-retest reliability was evaluated for 54 subjects asked to fill out the questionnaire for a second time.
The 54 subjects filled out the questionnaire for the second time days after the first time. Overall, the agreement between the first and the second set, related to test-retest measures intraclass correlation coefficient, was 0. In this work we use an alternative approach at the factor analysis. Our idea is to create a synthetic indicator to evaluate the expression of disgust and identify individual differences. The underlying idea of the SDI was to create a summary and normalized score that was able to differentiate between subjects based on the variability of their replies.
This allows better differentiation between subjects who present the same mean score and allows them to be ranked according to the variability of their responses. Negative values, although rarely seen empirically, can arise when a low mean score for disgust co-occurs with high variability between the various items.
From formula 2 it can be seen that that it would be difficult for a subject to present a variability of more than 0. Thus negative SDI scores are rare exceptions. The questionnaire was given to a sample of subjects males and females. Prior to analysing the responses to the SDI, an analysis of the respective averages for gender and age range was performed in relation to each item of the disgust questionnaire. The content analysis of the items, has identified four types of disgust related to oral e.
The Mann-Whitney U test was used to compare groups, since the assumptions of normality and homogeneity of variance were not met. The calculations are performed with SPSS ver. This analysis brought a number of interesting points to light. Overall the results showed that a gender difference is present for all classes of disgust with a significant SDI score in the female subjects involved table 2.
The analysis in different age groups revealed a different trend in different types of disgust. In females the maximum score was present in the first group for all dimensions of disgust. Our study aimed to investigate the differences regarding disgust in relation to gender and age and to focus on the types of disgust where the greatest divergences arose.
The various dimensions of disgust were analysed through the synthetic index SDI that enabled disgust to be investigated not only in relation to the overall average of responses but above all in relation to their variability. Types of disgust that we investigated concerned the disgust toward oral, aggressive, moral and contamination objects. As disgust can be considered a primary emotion, his goal is not only in relation to the feeling, but also to the object that elicits Phillips, A series of variables show that the oral object food is more in the first half of life with a difference between males and females and it highlights a decrease with age Fig.
Disgust is also culturally determined. The target of disgust may vary from culture to culture. Westerners might find it disgusting to eat insects, while in other cultures the same insects are seen as delicacies.
Disgust is a subjective response to an objective stimulus! Interestingly, some studies found that people who are disgusted more easily tend to have more conservative political views than people who are not disgusted as easily. The reason for this is likely to be the fact that conservatives are higher in fear of risk, and fear of risk is the basis for disgust. Disgust is not unique to humans. We can also see it e. The classical disgust face is the one we usually see in response to something that has a bitter taste.
Putting the tongue out in this facial expression means that we are trying to get rid of something poisonous in our mouth. Our response to bitterness in pre-programmed.
Our expression of disgust is similar to our response to bitterness. A way of stopping the feeling of disgust is altering our facial expression, e.
The reason for this is that not only our emotions create certain facial expressions, but also our facial expression feeds back into our thoughts and feelings. We use our facial expression to tell other people how we feel. People with Moebius syndrome are not able to express their emotions facially because the facial nerves needed have not been developed. This makes interacting with other people very difficult for them because facial expressions are an integral part of human interaction.
It alters what we think of other people. In this case, it is the disgust that infuses all our judgments. The whole interview can be listened to on the BBC homepage.
What can we learn from this? Disgust is an emotion that makes, from an evolutionary perspective, a lot of sense. It protects our health and life because it makes us stay away from poisonous food and from disease. This pattern would show that moral disgust vignettes could induce disgust-like patterns of neural activity independent of core disgust references within the vignette. In addition, it would also show that moral disgust vignettes could induce greater activation relative to the effects of their core referent word.
The purpose of the pilot work was to generate and evaluate a series of vignettes for the main study to ensure that they differed as expected on a range of characteristics including ratings of emotion, morality, intentionality, and wrongness. The vignette sets were moral disgust vignettes, moral anger vignettes, matched disgust vignettes that contained the same core disgust referents as the moral disgust vignettes, high disgust vignettes that were meant to induce greater disgust than the matched disgust vignettes, neutral control vignettes and scrambled vignettes see Table 1.
Obtaining such self-report data from participants in the main study would be problematic because we wanted scanning participants simply to read the vignettes and react to them without biasing them toward particular aspects of each vignette, such as whether they were disgusting or immoral.
We also did not get ratings from these participants before or after the main study because ratings under these conditions would either influence or be influenced by presentation during scanning. If administered before the task, it would have habituated the vignettes' elicitation of disgust, which is known to weaken with exposure i.
If administered after the task, any ratings might have been affected by habituation from experiencing them in the scanner. Thus, we utilized an independent group of participants to establish the vignette characteristics. We predicted the following basic differences between these groups of vignettes: 1 the moral disgust vignettes should be more disgusting and reflect greater purity violations than the moral anger vignettes, but the moral anger vignettes should reflect greater justice violations and be at least equivalent or more in terms of their ability to induce anger; 2 that the matched disgust vignettes should not be judged to reflect moral violations and that they should principally induce disgust, but that they should do so to a lesser extent than the high disgust vignettes; and 3 that the neutral and scrambled vignettes should not arouse much emotional feeling.
Specifically, all participants gave their written informed consent and all procedures of the study including the written informed consent, and the autonomy of each participant to stop at any point during the study were kept in line with the MQ HREC regulations.
Participants were presented with each of the vignettes in Table 1 in a different random order. For each vignette, participants were asked to rate how angry, happy, fearful, sad, and disgusted it made them feel, in each case using seven-point category scales 1 [Not at all] to 7 [Very].
In addition, for all vignettes except the neutral and scrambled ones, participants also rated: 1 How immoral is this scenario?
These ratings were always presented in the same order. Once all of the vignettes had been rated participants were allowed to stop and rest as needed the task was complete.
Participants' scores for each vignette were averaged and the unit of analysis was the vignette. Only the moral disgust, moral anger, matched disgust, and high disgust vignette groups were compared, as the control scores for neutral and scrambled vignettes had almost no variance with means excepting the happiness rating all around the lowest point on the rating scale.
Each rating type was analyzed using a univariate ANOVA, with vignette group treated as a between participant factor. This test is recommended to describe homogenous subsets of means Howell, All of the ratings, by vignette group, are presented in Table 2 , alongside the post-hoc contrasts conducted for each of the univariate ANOVAs described below. A post-hoc REGW Range test revealed three homogenous subsets, the matched disgust and moral anger vignettes as one, the high disgust as the next, and the moral disgust vignette group as the highest scorer on this variable.
A post-hoc REGW Range test revealed two homogenous subsets, the matched disgust and high disgust vignettes as one, and the moral disgust and moral anger vignette groups as the other and highest scoring subset on this variable. A post-hoc REGW Range test revealed two homogenous subsets, the matched disgust vignettes as one, and the remaining three vignette groups as the other and highest scorer on this variable. A post-hoc REGW Range test revealed three homogenous subsets, the matched disgust group of vignettes as one, the high disgust vignette group as the next, and the moral anger and moral disgust vignettes as the third and highest scoring subset on this variable.
There were no homogenous subsets. A post-hoc REGW Range test revealed two homogenous subsets, the matched disgust and high disgust vignettes as one, and the moral disgust and moral anger vignette groups as the other and highest scorer on this variable. A post-hoc REGW Range test revealed two homogenous subsets, the moral disgust vignette group as the first and highest scoring subset on this variable, with the remaining three vignette groups as the other subset.
A post-hoc REGW Range test revealed two homogenous subsets, the matched disgust and high disgust vignettes as one, and the moral disgust and anger vignette groups as the other and highest scorer on this variable. A post-hoc REGW Range test revealed three homogenous subsets, the moral anger vignette group as the first and highest scoring subset of this variable, the moral disgust vignette group as the second, and the matched and high disgust vignette groups as the third.
Table 2. The results from the pilot study confirmed that the vignettes were able to induce the requisite emotions and reactions in participants that we intended to investigate in the main study. The moral disgust vignettes were more disgusting and reflected greater purity violations than the moral anger vignettes, which in turn scored higher on justice violations but equivalent in anger to the moral disgust vignettes. The matched disgust vignettes were significantly less disgusting than the high disgust vignettes, and both these sets of vignettes were judged to be less immoral and wrong compared to the moral anger and disgust vignettes.
Perhaps most importantly, for our purposes, the matched disgust vignettes, which contained identical core elicitors to the moral disgust vignettes, were judged to be less disgusting, suggesting that participants regarded the addition of a degree of intentionality i.
That each of the vignette types generated a range of emotions is not itself a major issue. The dominant emotion in each case was consistent with our categorization of the vignettes. Indeed, most publications on this topic find that other emotions are activated beyond the target specific ones e.
Thus on the basis of self-report, participants felt that an immoral action involving a core disgust elicitor was more disgusting than the core elicitor without an immoral action. This idea was examined more directly in the main study where fMRI was used to investigate differences between moral and core disgust, rather than relying on self-report accounts. We used functional magnetic resonance imaging fMRI to measure the blood-oxygen level-dependent BOLD response in participants reading the various vignettes tested in the pilot.
The purposes of the main study were: 1 to determine if the brain areas activated by the matched disgust vignettes were largely the same or different from those produced by the moral disgust vignettes, as both used the same set of core disgust elicitors, but the latter involved moral violations and the former did not; 2 to see if brain activation induced by moral disgust vignettes more closely resembles that of the matched or the high disgust vignettes, on the basis that self-report disgust scores were closer in the pilot study for moral and high disgust, than for moral and matched disgust; 3 to test if activation differences between the high and moral disgust conditions were similar to activation differences between the matched and high disgust condition.
In both cases, the first mentioned set of vignettes groupings i. They were awarded course credit or received a small cash payment. All participants provided written informed consent and were recruited on the basis of the following self-reported inclusion criteria: 1 healthy; 2 neurologically normal validated by neuroradiological review ; 3 non-healthcare employed; 4 between the ages of 18 and 30 years; and 5 are able to undergo fMRI scanning i.
No pilot participants were involved in the main study. All procedures of the study including the written informed consent, and the autonomy of each participant to stop at any point during the study were in line with the MQ HREC regulations and the study protocol was approved by this committee.
Participants were presented with the vignettes validated in the pilot work and developed uniquely for this study on a monitor viewed via a mirror mounted on the headcoil to read while being scanned.
Participants were instructed to indicate button-press whenever a scrambled vignette appeared. The task was simply to ensure that participants were attending to the statements. The vignettes are presented in Table 1.
We used an event-related design with six runs. Each run involved presenting 55 vignettes. Of these 55, there were 10 vignettes drawn from each of the five conditions moral disgust, matched disgust, high disgust, moral anger, neutral.
A further five scrambled vignettes were randomly interpolated amongst these trials. Vignettes could only be selected once on each run from the moral disgust, matched disgust, high disgust, and moral anger conditions i. Each vignette was presented for a total of 6 s, with no inter-stimulus interval. Participants were asked to press a response button whenever a scrambled vignette appeared.
The first four volumes in each run were automatically discarded. Each run comprised 84 recorded volumes. First, all obtained volumes per participant were realigned and resliced to correct for small head-movements and slice timing correction was performed. The obtained transformation parameters were then applied to the co-registered functional volumes, which were re-sampled to a 2 x 2 x 2 mm voxel size. The spatially transformed functional data were spatially smoothed using a 6 mm FWHM isotropic Gaussian kernel.
A general linear model GLM was fitted to the data with five regressors. Each condition was modeled with a boxcar function and convolved with SPM's canonical hemodynamic response function. Furthermore, to remove low-frequency drifts, the default temporal high-pass data filter cut-off s was employed. A general linear model GLM was estimated for each participant with one regressor for each of the six conditions: five conditions of interest moral disgust, matched disgust, high disgust, moral anger, neutral and the scrambled vignettes.
The events were modeled using an event-related function lasting from the onset of each event to the onset of the following event. After fitting the GLMs, the scrambled condition was subtracted from each of the five conditions of interest i.
Table 3 presents the clusters and regional maxima for the three contrasts examining high, matched, and moral disgust conditions against the neutral control vignettes each of these first having the activation in the scrambled condition subtracted; i.
All three contrasts revealed activity in inferior, middle and superior frontal gyri, around similar coordinates. Similarly, activation occurred in the right mid-temporal and left fusiform gyri, in all three contrasts.
Fewer activations were observed for the moral and matched disgust contrasts in the occipital gyrus and for high disgust contrast in the superior and middle temporal gyri. Unique regional activations were largely absent on the left side. In the right hemisphere, there was both less activity than on the left and more limited overlap amongst the three contrasts. Activation in the frontal inferior gyri was observed for the matched and moral disgust vignettes, lentiform nucleus activation for the high and moral disgust vignettes.
There was more unique regional activity on the right side, but this was not clearly confined to one particular type of vignette. In sum, the three disgust-related vignettes, moral, matched, and high, produced similar and overlapping patterns of activation, characterized by left frontal regions and the fusiform gyrus. Table 4 presents the activations following high-matched, moral-high, and moral-matched disgust contrasts.
Overall, there were far fewer similarities between vignette types than observed in the disgust-neutral contrasts presented in Table 3. Figure 1 illustrates that for the moral-matched disgust contrast there were few activations, with these mainly on the right, and restricted to the uncus, culmen, and one sub-gyral location. On the left, the only activation was for the middle temporal gyrus, similar to an activation observed for moral anger see Table 6. Thus, after controlling for matched disgust, the moral component alone was associated with little unique neural activity.
Figure 1. Contrasts from fMRI data. Moral disgust vs. Different to Legend color i. Legend shows T-value of the contrasts e. Participants in the pilot study judged both the moral and high disgust vignettes as more disgusting than the matched disgust vignettes.
Thus, although both vignette types were perceived as more disgusting than the matched vignettes by participants in the pilot, the pattern of brain activation notably differed, including significant insula activation in the high-matched contrast.
This suggests a different neural basis for disgust reported for core elicitors relative to disgust reported for moral disgust elicitors. Figure 1 shows significant clusters in the left inferior frontal gyrus, inferior temporal gyrus, and middle and superior temporal gyri. Interestingly, anger-related activations see Table 6 were predominantly characterized by extensive left-middle temporal activations. Recall that the pilot data indicated that the moral disgust vignettes were more disgusting than the high disgust vignettes, and that the high disgust vignettes were more disgusting than the matched disgust vignettes—both to the same extent see Table 2.
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