Yeah, Helen Keller isn't the greatest example, 'cause she *had*
  vision 'til she was 2? or 4? I forget. Anyway, she had PLENTY of
  processing-time to get LOTS of raw data to be able to utilize
  later on in her Water moment, and plenty of stuff to analogize
  to in order to increase her knowledge about her surroundings,
  even if her input mechanisms were severely stifled.
  Basic circuits were formed; the rest is subconscious
  analogizing. Even when I learned about her in grade school, and
  saw some dramatic TV movie, I wasn't terribly impressed by Helen
  Keller.
  I'm 1/2 deaf and 1/2 blind myself - imagining myself in her
  shoes wasn't hard when I was 8, or now, but I like what she did
  with her life, and I honestly was more impressed by the teacher
  than by her.