Did You Know That The Brain Handles Reading and Writing Separately?
It’s true. Although the human ability to write evolved from our ability to speak, writing and talking are now such independent systems in the brain that someone who can’t write a grammatically correct sentence may be able say it aloud flawlessly.
In a paper published in the journal Psychological Science, a research team found it’s possible to damage the speaking part of the brain but leave the writing part unaffected — and vice versa — even when dealing with morphemes, the tiniest meaningful components of the language system including suffixes like “er,” “ing” and “ed.”
So a person can say, “The man is catching a fish.” The same person then takes pen to paper and writes, “The men is catches a fish.”
Amazingly the Brain treats writing and speaking in different areas. If one part is injured, the other may not be. When that happens you have these differences in communication.