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John Cronly-Dillon, Krishna Persaud, Richard Gregory, Chris Christou; Blind subjects explore and navigate the visual world using video images encoded in musical form. Journal of Vision 2002;2(7):511. doi: 10.1167/2.7.511.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To enable blind subjects to explore and navigate the visual world with reasonable confidence. Blind subjects need the same information as a sighted person, about FORM, SPATIAL location, and MOTION in order to explore and move about their environment with confidence. Without vision, information about (i) form is usually acquired through touching 3D objects situated within arms length or (ii) spatial location which is usually limited to the range that is covered through the use of the guide cane etc. Motion perception is difficult without vision, unless the target is a sound source, or the subject uses an echo-locating device. The advantage of vision is that it is a distance sense where visual images provide most of the information on form, location and movement required to explore and navigate the environment.
Method: We have developed a method that allows the subject to segment, and isolate selected features from video images of natural scenes that are pertinent to the perception of visual forms, ( ARVO 1998. 2000, Proc. Roy.Soc.B. vol.266 p.2427, 1999 vol 267.p2231), distance, and motion. These are encoded in musical form and the subject can listen to each in isolation or in combination. Blind, previously sighted subjects (lacking light sense), and blindfolded sighted subjects were given the task of locating and identifying a number of visual targets, randomly distributed about the laboratory. For instance, one task required them to locate a football (soccer) and goalposts, walk up to the football and kick it into the goal, which they could do quite easily.
Conclusion: Using a combination of feature extraction, image segmentation, and other strategies: looming, parallax etc blind previously sighted subjects are able to accomplish tasks that sighted people take for granted.
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