The Structure of Laboratory Dream Reports in Blind and Sighted Subjects

Ten college-educated young adults (four sighted, four congenitally blind, and two adventitiously blind) were studied in a sleep laboratory one night a week for 8 weeks. Dream reports were collected from electroencephalogram-defined sleep onset, rapid eye movement sleep, and non-rapid eye movement sleep, following a standard awakening schedule and interview format. Dream reports were analyzed in terms of subjects' responses to interview questions, which focused on formal organization and sensory contents in the dream. Subjects also were administered a number of tests of waking cognitive abilities, which suggested no general cognitive differences between sighted and blind subjects other than the greater clarity/incidence of auditory than visual imagery for blind subjects. Likewise, despite differences in the role which visual vs. other sensory imagery played in subjects' dreams, the dreams of congenitally blind and sighted subjects otherwise generally were comparable in composition and organization, and could be comparably discriminated in terms of the sleep stages from which they were elicited. Two congenitally blind subjects without any history of form vision were able to represent spatial relationships in dream experience without either visual imagery or compensatory imagery in other modalities. Two congenitally blind subjects with minimal form vision saw in their dreams only to the extent that they had been able to visualize in wakefulness with, once again, no adverse effect on either the momentary richness or the narrative continuity of dreaming. Two blind subjects who became legally blind as teenagers universally reported that their dream visualization was as their waking visual experience had been before they became blind. Moreover, their visual imagery included well defined imaginal representations of people and places known only since the acquisition of blindness. Overall, the results are consistent with the view that the dream is a constructive cognitive process, rather than a reproductive perceptual one, and with the view that the integrative cognitive systems responsible for both the momentary and the sequential organization of the dream do not depend on the presence either of contemporaneous visual-perceptual experience or of well developed visual cognitive codes.