Abstract

In a few seconds, touch can reveal a tactile picture’s shapes. The shapes are taken as representations. As examples, this chapter offers sketches drawn by EW, a blind adult. In theory, visible and tangible outline pictures rely on the same principle: a line can stand for a surface edge. The result is six options – combinations of foreground and background. The chapter argues that, in theory, edges, solid lines and dotted lines trigger an equation. For surfaces, two equations are needed.