Christopher, a 15 year old boy in "The Curious Incident of the Dog in the Night-Time", suffers from autism. The left half of his brain is undeveloped so that the right half has to make up for that deficiency. His left brain has literally taken over his right brain and he has lost all the abilities that right brain is associated with. He cannot understand why his father is angry with him or why his actions annoy others. He takes things literally and is not able to understand the nuances or intonations in speech. When asked by a policeman how old he was, he replies, "I am 15 years and 3 months and 2 days".
Our left brain is associated with things that require logic, reasoning, words, grammer, list making etc and other verbal things while right brain deals with imagination, drawing, music, feelings, and other non-verbal things. Being a left-brained kid, Christopher is very good in mathematics and reasoning. He can solve complex puzzles in an instant but cannot understand why hitting a policeman is wrong. And he'd certainly be very poor in writing fiction.
Writing is essentially a right-brain activity constrained by left-brain rules. Some people are naturally gifted writers (Saki) while some acquire this art through hardwork (Stephen King). But can the medium of writing, the means of putting words on paper, make a difference in the quality of the resulting prose? Can you write a higher quality essay by composing it in a word processor than on a notepad? And how is it affected by left/right division of human brain functionality?
One of the rules (or rather the only rule) for writing well is to write first and edit later. i.e. don't worry about grammer or spelling or coherency while writing your first draft. Just let your thoughts run wild. Do not pause to re-read; do not judge the quality of your prose; and certainly do not try to rephrase your sentences. In other words, write with your right brain and edit with your left brain. Notepad and typewriter are more conducive to this type of writing than a word processor. Once you comming something to paper using a notepad or a typewriter, it's not easy to go back and change it. So you are forced to move forward and let your right brain take control. But with a word processor, the tendency to edit on the fly is very strong; the words there are not concrete, unlike paper. The left brain takes over and this interrupts the flow of thought and slows you down.
Human brain thinks at a very fast pace and it is not possible to write down those thoughts at the same speed. Out of five ideas that occur to you, you might be able to wtire down only one or two of them, losing the rest. Some ideas so ephemeral or so unique that they never occur again. So for taking down your thoughts fast, word processor is the tool of choice. It is common to achieve typing speeds of 60 wpm or more with a little practice. Notepad fares worst in this regard. Some typewriters do allow you to type fast but a mechanical typewriter cannot hope to compete with an electronic computer.
Thinking while writing:
Some people think as they write. I.e. they don't have any well formed thoughts before they put the pen to the paper. They just let the plot develop as their pen moves. This type of writing is best done on a word processor because typing with both hands engages both halves of the brain, thus maximizing your creativity. A notepad or a typewriter is better suited for those who like to think first and write later. For them, the act of writing is not so much writing but recording of their thoughts.
Writing as drawing:
People with a very strong right brain tend to think of writing (with a pen) as an expressive act. When they write in cursive, it's like they are drawing, like they are moving brush on a painting. This helps them connect with their inner artist and makes them much more articulative. J. K. Rowling, author of Harry Potter series of books, prefers to write on a lined paper in longhand. She calls laptops 'so eighteenth century'.
A programmer, on the other hand, would do best as a writer when he thinks of writing as coding. Though coding is not strictly a traditional artistic field, it requires creativity nonetheless. This way of thinking adapts natually to writing on a computer.
Writing being stressful:
Some people find the act of writing on a paper to be too stressful. You have to take care of margins, spacing between words, spacing between letters, keeping a straight line etc. This puts so much pressure on the brain that there is no energy left to do the actual thinking. An extreme case of this is called Dysgraphia. So a dysgraphic person would write much better using a word processor where all these things are taken care of for him. Same goes for people who are too lazy to write on paper or are just not used to it.
Adopting a wrong style:
Whatever an author writes has to be submitted to the copy editors at the publishing house. And in today's wired world, this invariably means emailing your manuscript. This forces the writer to compose using a word processor as it would be too tedious to transcribe from a notepad later. In fact, most publishing houses provide MS Word templates which are to be used to compose your manuscripts! If a writer is forced to adopt a writing style that does not suit him, the result is bound to be of inferior quality.
Now I understand why I write better using a word processor. I am a programmer, I think as I write, and I am too lazy to write using a pen. So there you go!