To determine just what is the grossest sight, Valerie Curtis, the director of the Hygiene Center at the London School of Hygiene and Tropical Medicine devised a truly gruesome experiment. Curtis and a team of researchers presented 20 images of things perceived as repulsive to more than 80,000 individuals from 172 countries during a web-based survey.
Below are some of the images they used, with the top grossest one at the very bottom. Be warned: The graphic photo won first place for a very, very good reason. [Click for the full story ]
The images on the left of the wasp and caterpillars are not disease related, and so they ranked lower on the scale, respectively, than the parasitic human body louse and intestinal roundworms on the right.Alien Coffee Mug: Get Yours in the SPACE.com Store
Because blue is not commonly found in nature, the images on the left did not trigger a high level of disgust in people. Tinged with yellow and red, the images seemingly containing human bodily fluids suggested disease threats and caused disgust.
Compared to a photo of a healthy man, an image of that same man, but sick and sweaty, rated more than twice as disgusting. Similarly, a cramped train where you might inhale people's germs rated higher in disgust than an empty one.
The photo on the left is of a clean burn caused by scalding water and does not show signs of infection. The gruesome photo on the right is of post-operative infection following colostomy surgery.
The photo that universally raked the highest in the "gross-out" ratings was of a man's gums infested with live fly larvae, receiving close to a perfect score of 5. "The photo of the gums infected with maggots is the clearest representation of a parasite invasion," Curtis told Life's Little Mysteries. "The image acts as a warning that this individual poses a clear disease threat, and people instinctively want to avoid that."