Tactile vision substitution: past and future.

Tactile sensory substitution for blind persons has been studied primarily in a laboratory setting. Although the studies demonstrated the feasibility of the approach, to date no practical systems are in use. In this paper, previous tactile vision substitution studies are described, and the reasons why practical systems have not yet been developed are discussed. The theoretical basis for sensory substitution is examined primarily in regard to the capacity of the somatosensory system to mediate high resolution "visual" information. Future developments that may lead to practical systems for blind persons are considered.