The Mysterious Case of a Man Who can Read Letters but not Numerals

A recent finding has thrown up a puzzle before neuroscientists, with some of the view that our perception of human awareness and brain function might need changing. The finding stems from a man, his initials being R.F.S. Mr. RFS can read words with no hindrance. He can also do arithmetic calculations in his head, but cannot comprehend Arabic numerals from two to nine at all, though he can read Roman numerals and perform mental calculations with them. The finding was recently reported in the peer-reviewed scientific journal Proceedings of the National Academy of Sciences (PNAS).

The researchers showed the man the number eight and asked him to draw what he saw on the screen. RFS saw the number as some jumbled lines. The picture below illustrates what he saw.

Image Source: Science Magazine

Since 2010, RFS has been suffering from a rare kind of neurodegenerative disorder called the corticobasal syndrome, which manifests itself with problems in movement and language. According to the PNAS paper, his brain scans revealed widespread damage of his brain combined with volume loss in the cerebral, midbrain and cerebellar regions. Initially, he had developed amnesia with temporary vision loss coupled with an inability for expressing and understanding speech. With time, he also developed difficulty in walking.

RFS was initially at The Johns Hopkins Hospital and consulted Michael McCloskey, a co-author of the paper. McCloskey, a scientist at the Department of Cognitive Science at Johns Hopkins, began studying RFS in 2011 with a team.

According to McCloskey, RFS – the man in question – knows he is seeing a number, but he cannot comprehend what exactly the number is. In its place he ends up seeing jumbled lines. For the team, the striking fact is that he can see anything else but the numbers. “It's also surprising that his brain doesn't have problems with “0” and “1”. It's not clear why, but those two numbers might look similar to letters like “O” or "lowercase “l”. Or those two numbers might be processed differently than other numbers in the brain, as zero wasn't invented for quite a long time after the other digits were,” McCloskey told science website Live Science.

Experiments on RFS’ Brain

To understand what was happening inside his brain, the team carried out a series of experiments and measured the electrical activity in his brain.

The researchers embedded the image of a face into a number. RFS could not see the face embedded into the number. His best guess was that there was a number which appeared to him to be some jumbled lines. However, intriguingly, brain recordings showed a similar pattern when RFS saw a face with no numbers embedded.

The case with words was similar. When words like ‘tuba’ were shown to him embedded in a number, he could not see the words, which he could easily do otherwise. However, his brain mapping showed similar patterns, whether the word was embedded in a number, or alone.

According to McCloskey, it is clear that RFS’s brain is processing the numbers normally, yet he does not have the awareness of the numbers. “We think RFS' brain is just like everybody else's except that his disease has damaged...something… that has to happen for awareness. He does the brain work to determine what he's looking at, but then the additional work to be aware of it is going wrong,” the scientist was quoted saying.

This finding is new to neuroscientists and reveals the fact that much of the human brain remains to be understood. It also implies that cognitive functions of the brain and our visual senses might not be directly linked.