By Joseph Bennington-Castro

Whether we realize it or not, most of us have a knee-jerk reaction when we see someone with a facial disfigurement, such as psoriasis, a cleft lip, or a birthmark. We may sit away from them on the bus, hesitate to shake their hand, or even give a barely masked look of revulsion. A new study suggests these disgust reactions stem from an ancient disease-avoidance system that normally prevents us from catching illnesses. Essentially, we treat facial disfigurements like infectious diseases.

Psychologists have recently begun to uncover where disgust comes from, with some researchers believing the emotion is similar to fear. "Fear evolved to keep you away from large animals that want to eat you from the outside," says Valerie Curtis, a behavioral scientist at the London School of Hygiene and Tropical Medicine, who wasn't involved in the study. "Disgust evolved to keep you away from smaller animals that kill you from the inside." Our subconscious minds constantly scan the environment for signs of potential diseases, she says. If we see one, disgust kicks in and we avoid that object or person like the plague.

But it seems our disease-avoidance system sometimes gets it wrong. Previous studies suggested these mistakes underlie the aversion people have to various disfigurements. For this to be true, our responses to people with facial disfigurements, which aren't contagious, would have to be the same as our responses to people with infectious diseases.

To test this idea, psychologists at Macquarie University in Sydney, Australia, had 98 participants watch three videos of a person interacting with an object. Each featured a different actor—one who looked healthy, one who had a port-wine stain birthmark, and one who had flulike symptoms. The clip ended with the model putting a prop—a snorkel, towel, or harmonica—in his mouth. The participants then had to imitate the actors, whom they believed had just used their props.

Researchers recorded how far the participants were willing to go with their imitations and how often they made disgusted faces or exhibited disgust-related behaviors, such as wiping the prop. The participants' reactions to the objects used by the sick and disfigured models were the same. They avoided placing the props near their mouths and expressed equal disgust toward the objects, despite reporting influenza as being much more contagious, lethal, and disgusting than the birthmark in a questionnaire.

"The facial birthmark seems to be treated as a disease cue - a false alarm in this case," the researchers write in their study, to be published in an upcoming issue of Evolution and Human Behavior.

Curtis isn't surprised by the study's results. She says it further establishes that disgust is rooted in disease avoidance. The work shows how "we are often unaware of the deeper reasons for our actions," adds Justin Park, a psychologist at the University of Bristol in the United Kingdom. And psychologist Mark Schaller of the University of British Columbia, Vancouver, in Canada, notes that the study suggests that these seemingly prejudiced responses may be inborn. "Even if we know these people are perfectly healthy, our minds are responding to them as if they're not."

So is there anything we can do to change our behavior? Education is a good start, says Park. People don't seem to be born with a full catalog of disease signs to avoid, he says. Rather, we learn what a "normal" appearance is through our experiences. At the same time, we become more comfortable with something after being exposed to it often. "So one thing we could do is make atypical appearance more familiar and mundane," possibly by showing people with these types of appearances on television more often, he says.

Additionally, "research shows the initial prejudiced responses [to people with illnesses] tend to be stronger among people who personally feel vulnerable to disease," Schaller says. For example, people who recently received immunization against seasonal flu appear to have reduced disease-based prejudices. But this effect could potentially work for other kinds of interventions that make people feel less vulnerable to disease, such as better health care. "You could make an argument that any kind of society-level public policy that provides a health-related safety net to people would help reduce this problem," says Schaller.


ScienceNOW, the daily online news service of the journal Science

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Photos by Associated Press.
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  • <strong>Warning: The following slides contain graphic images.</strong>

  • This three-photo combination shows Dallas Wiens, the recipient of the first full face transplant in the United States. On the left, a 2008 Wiens family photo provided by Brigham and Women's Hospital, shows Wiens with his daughter Scarlette prior to an electrical accident that disfigured his face; center, a December 2010 file photo provided by Parkland Health and Hospital System in Dallas, and released by Brigham and Women's Hospital in Boston, shows Wiens prior to receiving a full face transplant during the week of March 14, 2011; and right, shows Wiens as he takes questions from members of the media during a news conference at Brigham And Women's Hospital, in Boston, Monday, May 9, 2011. (AP Photo/Wiens Family, Parkland Health and Hospital System in Dallas, and Steven Senne)

  • Undated photos provided Thursday, Aug. 11, 2011 by the Nash family and Brigham and Women's Hospital show chimpanzee attack victim Charla Nash before she was attacked by a chimpanzee and a recent photo release by the hospital Thursday Aug. 11, 2011 showing Nash after face transplant surgery, right. Nash was mauled by a chimpanzee in 2009 and received the transplant in May 2011 at Brigham and Women's Hospital in Massachusetts. Nash, 57, said in a statement she's looking forward to doing things she once took for granted, including being able to smell, eat normally, speak clearly and kiss loved ones. (AP Photo/Brigham and Women's Hospital, Lightchaser Photography)

  • These undated file photos provided Thursday, Aug. 11, 2011 by the Brigham and Women's Hospital show chimpanzee attack victim Charla Nash after the attack, left, and post-face transplant surgery, right. The U.S. government wants to start regulating face and hand transplants just as kidneys, hearts and other organs are now. That means establishing waiting lists, a system to allocate body parts and donor testing to prevent deadly infections. Officials say this is a big step toward expanding access to these radical operations, especially for wounded troops returning home. The new rule is expected to take effect later in 2012 or early 2013. (AP Photo/Brigham and Women's Hospital, Lightchaser Photography, File)

  • 37-year-old Richard Lee Norris of Hillsville, Virginia, was injured in 1997 in a gun accident. Richard Lee Norris from Hillsville, Virginia, underwent the 36-hour operation last week after living as a recluse for 15 years. Doctor's say he has also regained his sense of smell. Due to the accident, Mr. Norris lost his lips and nose and had limited movement of his mouth. The transplant took place at the R Adams Cowley Shock Trauma Center at the University of Maryland Medical Center. Physicians say it is the most extensive face transplant ever carried out, including new teeth, nose, tongue and jaw. The surgery was funded by the US Navy, which hopes the techniques will help casualties from Iraq and Afghanistan. Surgeons who carried out the operation said it was part of a series of transplant operations lasting 72 hours, using organs from one donor in five patients, including Mr Norris. (Rex Features via AP Images)

  • 37-year-old Richard Lee Norris of Hillsville, Virginia, was injured in 1997 in a gun accident. Richard Lee Norris from Hillsville, Virginia, underwent the 36-hour operation last week after living as a recluse for 15 years. Doctor's say he has also regained his sense of smell. Due to the accident, Mr. Norris lost his lips and nose and had limited movement of his mouth. The transplant took place at the R Adams Cowley Shock Trauma Center at the University of Maryland Medical Center. Physicians say it is the most extensive face transplant ever carried out, including new teeth, nose, tongue and jaw. The surgery was funded by the US Navy, which hopes the techniques will help casualties from Iraq and Afghanistan. Surgeons who carried out the operation said it was part of a series of transplant operations lasting 72 hours, using organs from one donor in five patients, including Mr Norris. (Rex Features via AP Images)

  • In this Aug. 20, 2008, file photo, Carmen Tarleton is interviewed in her home in Thetford , Vt. The Vermont woman who was burned and disfigured when her ex-husband doused her with industrial lye four years ago has been approved for a face transplant at a Boston hospital.(AP Photo/Toby Talbot)

  • UCLA's animated graphic video explains how face transplantation is done.