Strategic use of spatial representations to maintain orientation by individuals who are congenitally totally blind and blindfolded sighted people
Cummins, Peg A.
:
2006-04-17
Abstract
While walking within room-sized spaces, blindfolded sighted people tend, spontaneously, to construct two-dimensional spatial representations of that space. As they walk, they couple kinesthetic input acquired when walking with the space as represented thereby enabling them to keep track of their positions. Individuals who are congenitally totally blind appear to construct sequential rather than spatial representations of the space through which they move. The specific roles of the coupling effect hypothesized by Rieser (1999) and of translations and rotations in maintaining orientation have not been adequately investigated. To investigate this, individuals who were congenitally totally blind and individuals with normal, but occluded vision, walked routes and then pointed to their places of origin. They did so under four conditions: In an imagined surround, they imagined the placement of objects from a familiar setting and in a virtual ganzfeld; they were given no instructions for completing the task. While walking the routes they either translated only, or translated and rotated. The individuals who were congenitally totally blind also participated in a second study wherein they imagined they walked within a Braille cell under the same four conditions.
Individuals who are congenitally totally blind were significantly slower at pointing at a target suggesting they did not construct spatial representations of the space through which they moved while in transit. Rather they appeared to construct them in retrospect. Both groups of participants performed significantly better in the translation only condition. Rotations introduced an element of error in the performance of both groups of participants. Possible reasons are discussed.