Prosopometamorphopsia (PMO) is a rare disease in which sufferers perceive other people's faces in a distorted manner. A team of researchers from Dartmouth College in the US used a 58-year-old patient to visualize the grimaces he described as “demonic” Compared to healthy people, the affected person sees faces that resemble gnomes or other fantasy creatures from fantasy films.
The researchers were able to achieve such a visualization for the first time, as the disorder only appeared in the face of other people and not in pictures of people.