June 4 (UPI) -- Disgust helps people avoid potentially dangerous situations of disease and infection, and a new study groups types of disgust into six distinct categories -- which suggests these responses could be used to further steer people from harm.
Researchers, led by the London School of Hygiene & Tropical Medicine, studied 2,500 people online, listing 75 potentially "disgusting" scenarios. Their findings were published Monday in a special issue of the Philosophical Transactions of the Royal Society.
"Although we only really came to understand how diseases transmit in the 19th century, it's clear from these results that people have an intuitive sense of what to avoid in their environment," research co-leader Dr. Micheal de Barra, who lectures in psychology at Brunel University London, said in press release. "Our long coevolution with disease has 'wired in' this intuitive sense of what can cause infection."
The researchers said the findings could help increase public health messages, including encouraging handwashing with soap or countering the stigma associated with sickness.
The situations were grouped into six areas:
- Hygiene, including displays and physical evidence.
- Animals and insects, including mice and mosquitoes.
- Sex, including promiscuous sexual activities.
- Atypical appearance, including abnormal body shape, deformity, behavior such as wheezing or coughing, signs of homelessness.
- Lesions, including infection on the body surface such as blisters, boils or pus.
- Food, including signs of spoilage.
The participants, who mainly were from the United States, Britain and Canada, were asked to rate the strength of their disgust to each scenario on a scale ranging from "no disgust" to "extreme disgust." Infected wounds producing pus were rated as the most disgusting. The mean age of participants was 28 years, and 44 percent of participants were students.
Specific examples of potentially disgusting things included accidentally borrowing someone else's roll-on deodorant, small red dots on another person's genitals, and someone coughing into your face.
Women rated all six categories as more disgusting than male participants, with women listing risky sexual behavior and animals carrying disease as the most disgusting.
"It appears that cues to infectious disease threats are not categorized following the abstract biomedical categories of disease transmission risk recognized in the literature ... but, rather, as categories of recognizable cues as to what to avoid," the researchers wrote in their paper.
"These include potentially contaminated objects such as bodily fluids, infected lesions, spoilt foodstuffsand animals that vector disease, practices, such as those that run the risk of contracting sexually transmitted diseases, and people who display visible signs of disease or poor hygiene."
Many of these aspects were related to diseases, such as eating rotting food leading to cholera, getting in close contact with unhygienic people could transmit leprosy, promiscuous sexual practices could lead to syphilis and contact with open wounds might led to the plague or smallpox infection.
"This type of disease avoidance behavior is increasingly evident in animals, and so leads us to believe it is evolutionarily very ancient," said Dr. Val Curtis, a disease control researcher and "disgustologist" from the London School of Hygiene & Tropical Medicine. "Although we knew the emotion of disgust was good for us, here we've been able to build on that, showing that disgust is structured, recognizing and responding to infection threats to protect us."