Why do people that are blind or deaf have all their other senses heightened?

Question: Why do people that are blind or deaf have all their other senses heightened?
- Keywords:
  blind,
  body,
  deaf,
  human,
  senses
Asked by dognut99 to Ed, Hayley, Jason, Nathan, Sophie on 18 Mar 2013.
- Jason King answered on 18 Mar 2013:
  
  Hi, it’s not so much that their other senses actually get better, it’s more that people concentrate on them more, so you learn how to get the most information from your ears, or touch. The actual ear, or fingers don’t themselves change.

Question: Why do people that are blind or deaf have all their other senses heightened?