In a new study thought to be the first of its kind, researchers detail a nearly decade-long journey to understand how corticobasal syndrome left an American scientist unable to see the digitals two through nine, instead referring to what he saw as “spaghetti”-like symbols.

Recently published in Proceedings of the National Academy of Sciences, the study documents the symptoms of a 60-year-old man identified by the initials RFS. He began working with the researchers in 2011 to better understand his inability to recognize, name, copy or comprehend the digits two through nine, either on their own or when they appeared as parts of larger numbers.

“He described the appearance of these digits as a tangle of black lines with no discernible relationship to any recognizable shape,” the researchers wrote.

The research team, comprised of researchers at Johns Hopkins University, Harvard University, and other institutions, believe the corticobasal syndrome somehow affected the signals that travel between the parts of the man’s brain responsible for perceiving visual information and those responsible for translating it into something understandable, leading to his unique symptom. However, they remain unsure how exactly this disruption happens and why it only affects certain numbers.

“This is a really unique case that disrupts our intuitions about the way we think we see things,” Teresa Schubert, a neuropsychologist at Harvard and lead study author told Popular Science. “When most of us think of ‘seeing,’ we think that an image comes through our eyes and is processed by the brain, and then, sight. But what this case is really showing us is that your brain can be unconsciously detecting a face or a digit or even reading a word without you actually ‘seeing’ it.”

Despite the visual disruption, the man’s understanding of numbers and the concepts of mathematics are still all intact. Researchers were able to help him develop a set of placeholder symbols to use as replacements for two through nine and those symbols, which he still uses to retain phone numbers and other numerical information, helped him to keep his job as an engineering geologist until 2014.

To read the full story, click here.