Of course blind people dream. Exactly how they dream, and whether their dreams include visual images depends on several factors. It seems that the most important thing in determing the visual content of a blind person's dream is if the person was always blind, and if not, when sight was lost. Joseph Jastrow, who was blind himself, studied the dreams of blind people while researching his book Fact and Fable in Psychology. One of the people he interviewed was Helen Keller who had this to say about her dreams:
"My dreams have strangely changed during the past twelve years. Before and after my teacher first came to me, they were devoid of sound, of thought or emotion of any kind, except fear, and only came in the form of sensations. I would often dream that I ran into a still, dark room, and that, while I stood there, I felt something fall heavily without any noise, causing the floor to shake up and down violently; and each time I woke up with a jump. As I learned more and more about the objects around me, this strange dream ceased to haunt me; but I was in a high state of excitement and received impressions very easily. It is not strange then that I dreamed at the time of a wolf, which seemed to rush towards me and put his cruel teeth deep into my body! I could not speak (the fact was, I could only spell with my fingers), and I tried to scream; but no sound escaped from my lips. It is very likely that I had heard the story of Red Riding Hood, and was deeply impressed by it. This dream, however, passed away in time, and I began to dream of objects outside myself."
As Keller began to learn to relate to the world outside of herself, her dreams began to take form, to be easier to name and interpret. No longer were her dreams just frightening sensations.
Most researchers believe that the critical time that determines whether a person will dream with visual imagery is between 5 and 7 years old. People who went blind before the age of 5 usually have no visual component to their dreams, while those who lost their sight after age 7 do. Jastrow believed this to be due to brain development, and the inability to create verbal metaphors for sights seen before that age. Jastrow stated:"The dreams of seeing and hearing probably reflect far more of conceptual interpretation and imaginative inference than of true sensation; yet they are in part built up upon a sensory basis." He believed that children prior to age 5 just didn't have the language skills to interpret and recreate what they saw.
The lack of visual images in dreams doesn't limit the dreamer's imagination or richness experienced in dreams, however. Instead of seeing a train in a dream, a blind person might experience the sounds, smells and vibrations of the train. As a matter of fact, a more recent study Hurovitz, C., Dunn, S., Domhoff, G. W., & Fiss, H. (1999) concluded that while the dreams of sighted individuals rarely contained taste, smell, or touch sensations, the dreams of the blind usually did.
The dreams of the blind have every bit of meaning and intensity of those who can see. It is interesting that one of the great interpreters of dreams, the ancient Greek Tiresias, was blind. The dreams recorded by blind people in the above studies tended to include less aggression on the part of the dreamer towards others, and more misfortune (ie. accidents, deaths, injuries). This was consistent with the overall conclusion that we experience dreams much as we experience life.
Just something kind of cool to think about.
An interesting subnote (thanks etouffee)!! When deaf people dream, all the speech is in sign language. (Assuming the person knows sign language I guess)