No, he does not consume any illegal substances that may alter his perception. The 58-year-old man, who presented himself to the neurologist at Dartmouth College in Hanover, USA, reported that he doesn’t even take medication regularly. The patient had a remarkable medical history to tell: He suffered from bipolar and post-traumatic disorder; at the age of 43 he had been in hospital with a head injury; at the age of 55 he had survived carbon monoxide poisoning. Was that the reason why four months later his perception had permanently changed in such a bizarre way? In any case, he reported to the experts, since then he has only seen all of his fellow human beings with grimacing faces, with distorted head shapes and deep furrows on their foreheads, cheeks and chins.
The knowledgeable researchers led by Antônio Mello and Brad Duchaine from Dartmouth College diagnosed what was obviously a case of prosopometamorphosia – so rare that they diagnosed the case immediately in the specialist magazine Lancet could publish. Only 75 cases in total are known from the scientific literature worldwide. Not to be confused with the much more widespread prosopagnosia, the inability to recognize people based solely on their faces. Up to two percent of all people probably suffer from this to varying degrees. What both conditions have in common is that they only affect the recognition of faces, otherwise visual perception is unclouded.
He continues to recognize friends and family, even if they now look completely different
This was also the case with the Dartmouth patient, who had no problems whatsoever when looking at objects, such as houses or cars. But, unlike those affected by prosopagnosia, he could still identify his friends and acquaintances, except that they looked, well, a little like demons. He also achieved full marks in various neuropsychological tests.
In addition, and this makes the new case unique, the patient was only able to recognize people as grimaces in the immediate face, but unchanged on paper or on the screen. This gave the researchers the unique opportunity to reconstruct his individual perception: they simultaneously presented him with a real person and their portrait on a computer monitor. Image editing software was then used developed together, what the alienated face looks like. “We believe that such images have not existed before,” write the authors.
Of course, the researchers also used imaging techniques to look for possible causes of the bizarre syndrome in the affected person’s brain. They discovered an abnormality in the hippocampus, probably the result of a small cyst. Its significance is unclear; research also knows cases of prosopometamorphosia without any noticeable changes in the brain structure.
The disorder is too rare for it to be worthwhile – and even possible – to delve much into the pathogenesis. But it is still important because the neurological syndrome once again proves that human perception is not a video camera with a screen connected to the brain, but an extremely complex and error-prone process. And, at least in this case, it shows people’s ability to adapt, as the researchers report: “The distortions were initially very disturbing for him, but he got used to them.”