Facial disgust in response to touches, smells, and tastes.

Disgust serves to defend the body from the entry of toxins and disease. Central to this function is a strong relationship with the proximate senses of smell, taste, and touch. Theory suggests that distinct and reflexive facial movements should be evoked by gustatory and olfactory disgusts, serving to impede bodily entry. While this hypothesis has received some support from facial recognition studies, whether smell and taste disgusts actually produce distinct facial responses, is unknown. Moreover, there has been no assessment of the facial response evoked by contact with disgusting objects. To address these issues, this study compared facial responses to touch, smell, and taste disgusts. Sixty-four participants were asked to touch, smell, and taste disgust-evoking and neutral control stimuli, and rate them on disgust, on two occasions-first, while they were video recorded and second, with facial electromyography (EMG) applied (measuring levator labii and corrugator supercilii activity). Videos were coded for facial expressions by humans and for facial action units (FAUs) by machines. Self-report data confirmed the disgust stimuli as highly disgusting. Comparison of the overall pattern of FAUs evoked by touch, smell, and taste disgusts, indicated two distinct facial disgusts for the proximate senses-a chemosensory and a tactile-disgust face. The nose wrinkle and upper lip raise were central to all facial disgusts, indicating their centrality to the disgust face. Several facial disgusts appear to exist, each with different functional goals. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Effects of sickness manipulation on disgust and pleasantness in interpersonal touch.

The theory of the behavioral immune system (BIS) describes a set of behaviors that protect the individual from infectious diseases and that are motivated by disgust and the perceived vulnerability to disease. As interpersonal touch is one of the most common situations of potential transmission of infectious diseases in our everyday life, it seems likely that being touched by an apparently sick individual activates disgust. Our aim was to determine if risk of contamination from interpersonal touch alters the pleasantness of interpersonal touch and modulates facially expressed emotions. In total, 64 participants received interpersonal stroking by either a healthy or by sick-appearing experimenter. Half the strokes were performed at a slow velocity of 3 cm/s and half at a faster velocity of 30 cm/s, to modulate the degree of C-tactile fiber activation in the touch perceiver. While the experimental sickness manipulation did not influence the reported touch pleasantness, there was a tendency for a diminished expression of happiness in the slow stroking condition. In addition, the desire to clean the arm after stroking correlated positively to disgust sensitivity and to germ aversion, which is a subscale of the perceived vulnerability to disease. Contrary to previous studies, participants did not prefer the slow over the fast stroking velocity, irrespective of sickness induction. Our results lead us to assume that disgust in interpersonal touch depends especially on the touch receiver and we speculate that a rather conservative reactivity of the BIS allows for an adaptive behavioral balance in interpersonal relations. This balance may be needed to weight the risks of contamination against the benefits of interpersonal touch for social interaction.

The source effect as a natural function of disgust in interpersonal context and its impairment in mental disorders.

Disgust affects interpersonal relationships and regulates hygienic, sexual and distance behaviour. Its intensity in the interpersonal context depends on the character of the relationship. Strangers normally evoke more disgust than intimates (known as the source effect). General disgust sensitivity is increased in various mental diseases. It is unclear how disgust in the interpersonal context is affected and whether the source effect is preserved. 460 inpatients with mental disorders and 463 healthy subjects answered a newly developed Questionnaire (DIRQ) that covers disgust in the interpersonal context on content categories (hygiene, physical proximity, sexuality) and on source categories (self, partner, parent, stranger). Mental disorders were diagnosed with structured interviews. Healthy controls exhibited a pronounced source effect, with strangers evoking more disgust than intimates. In patients, this source effect was reduced (Cohen's d = 0.3), especially for sexual disgust, while general disgust sensitivity was increased (d = 0.5). High disgust in patients was best predicted by a history of sexual abuse and by the presence of post-traumatic stress disorder. In conclusion, mentally impaired patients show increased and trauma-associated disgust sensitivity. Their downregulation of sexual disgust in intimate relationships is hindered, which may have a boundary protective function but might also fuel difficulties engaging in relationships or intimacy.

Retronasal testing of olfactory function: an investigation and comparison in seven countries.

Flavor perception is to a large extent determined by olfaction, and persons who lost their sense of smell consequently complain about strongly reduced enjoyment of food. The retronasal olfactory function is especially important for flavor appreciation. The aim of this study was to compare retronasal function across different cultures and to develop a test that is applicable across cultures. Identification of 39 retronasal applied odor probes was tested in a total of 518 participants of seven countries; 292 of them were healthy, and 226 exhibited a smell disorder. A retest was performed with 224 of the healthy participants. Furthermore, all participants were tested for orthonasal threshold, identification, and discrimination ability. Significant cultural differences in identification ability were found in 92% of the probes. The 20 probes that could be identified above chance in healthy participants of all countries and that could differentiate between patients and controls were selected for the final retronasal test. This test was well able to differentiate between controls and patients in different countries and showed a good coherence with the orthonasal test (r = 0.80) and a good retest-reliability (r = 0.76). Furthermore, it is age-independent. The strong cultural differences observed in retronasal identification underline the necessity to develop a culturally independent instrument. This retronasal test is easy to apply and can be used across different countries for diagnostics and clinical research.

Major histocompatibility complex peptide ligands as olfactory cues in human body odour assessment.

In many animal species, social communication and mate choice are influenced by cues encoded by the major histocompatibility complex (MHC). The mechanism by which the MHC influences sexual selection is a matter of intense debate. In mice, peptide ligands of MHC molecules activate subsets of vomeronasal and olfactory sensory neurons and influence social memory formation; in sticklebacks, such peptides predictably modify the outcome of mate choice. Here, we examine whether this evolutionarily conserved mechanism of interindividual communication extends to humans. In psychometric tests, volunteers recognized the supplementation of their body odour by MHC peptides and preferred 'self' to 'non-self' ligands when asked to decide whether the modified odour smelled 'like themselves' or 'like their favourite perfume'. Functional magnetic resonance imaging indicated that 'self'-peptides specifically activated a region in the right middle frontal cortex. Our results suggest that despite the absence of a vomeronasal organ, humans have the ability to detect and evaluate MHC peptides in body odour. This may provide a basis for the sensory evaluation of potential partners during human mate choice.

Patient adjustment to reduced olfactory function.

OBJECTIVE: To compare the importance of olfaction in daily life between patients with olfactory disorders and healthy normosmic individuals. DESIGN: Quasiexperimental. PARTICIPANTS: A total of 470 individuals (235 anosmic or hyposmic patients and 235 normosmic control individuals). MAIN OUTCOME MEASURES: The Individual Importance of Olfaction Questionnaire (IO) and olfactory testing using the "Sniffin' Sticks" test kit. RESULTS: The IO scores were lower in people with smell disorders compared with normosmic subjects (P < .001) and lower in patients with anosmia compared with hyposmic patients (P < .001). CONCLUSIONS: These scores suggest adjustment processes in the daily use of the sense of smell by patients. Patients attach less importance to their current sense of smell in daily life than do normosmic individuals. This adjustment might be an example of regaining psychological health despite acquired and long-lasting impairments.

Quality of life following nasal surgery.

OBJECTIVES/HYPOTHESIS: This prospective study aimed to investigate changes in quality of life (QOL) after nasal surgery. STUDY DESIGN: Prospective study. METHODS: A total of 788 patients (492 men and 296 women; age range, 9-81 years; mean age, 41 years) were included in this prospective study. Three hundred thirty-six patients received sinus surgery, 358 received septum surgery, and 94 additional patients received sinus surgery involving the septum. QOL was assessed with a standardized questionnaire for general health and well-being (36-Item Short Form Health Survey [SF-36]). Additionally, subjective sinonasal impairment was collected using the Rhinosinusitis Disability Index (RSBI). QOL and subjective sinonasal impairment were retested 4 months after surgery (63-339 days after surgery; mean, 128 days) in 361 patients. RESULTS: In the RSBI severity scale, 29.5% of the patients rated their sinonasal problems presurgery to be of high severity, 61.2% rated them as medium, and 9.3% as minor. Postsurgery, 2.8% of the patients rated the severity of their sinonasal problems high, 35% medium, and 62.2% minor. Subjective improvement of symptoms was found in more than 80% of the patients. Presurgery, general QOL (SF-36) was impaired in sinus patients and improved significantly after surgery. For most septum patients we found relatively little impact of sinonasal disease on general QOL (SF-36) compared to the German normative sample. CONCLUSIONS: Functional endoscopic surgery seems to be a good technique for reducing sinonasal symptomatology in the majority of patients. It appears to enhance QOL in those patients who were severely affected beforehand. Long-term investigations are currently underway to further explore the patients' subjective QOL following nasal surgery.

Individual significance of olfaction: development of a questionnaire.

Clinical experience shows that the individual significance of olfactory function varies between subjects. In order to estimate these individual differences we developed a questionnaire to study the subjective importance of the sense of smell. Questions were arranged within three subscales: association with olfactory sensations, application of the sense of smell, and the readiness to draw consequences from the olfactory perception. The questionnaire was shown to be time efficient, suitable for normosmic subjects and patients with hyposmia or anosmia. It exhibited a good internal reliability (Cronbach's Alpha = 0.77). First results in 123 subjects indicate that the subjective importance of the sense of smell stays at the same level throughout life-span despite of a decreased olfactory sensitivity. Furthermore, women reported a higher importance of olfaction. It is hoped that this questionnaire will contribute to clarify, for example, cross-cultural differences in the perception of odours.