The paper reviews the effects of absence of vision on perceptual functioning and considers ways in which a modified Optacon (which translates images into tactile presentations) can help visually impaired persons acquire critical cognitive and perceptual knowledge. Background research with the Tactile Vision Substitution System, a system for converting an optical image into a tactile display, is reviewed. Modification of the standard Optacon is described, and its use in exploring three dimensional objects is noted. Supplementary uses, such as pictorial representation of illustrations and signature development, are also considered. (CL)