Object recognition from two-dimensional tactile graphics: What factors lead to successful identification through touch?

Tactile Graphics (TG) are raised line diagrams to represent pictorial content for People with Visual Impairments (PVI). While shapes may be simple to depict, objects often appear disjunctive when represented in graphics. Researchers have evaluated the efficacy of TG and stated factors like size, complexity, or prior visual experience, affecting identification. However, the specific features of a graphic or aspects that enable object (3D) recognition through them need investigation. We evaluate the interactions of 12 PVI (8 born-blind and 4 late-blind), having minimal experience with TG or graphical representations, with 20 tactile stimuli including daily objects. We present graphic- and process-based factors that aid recognition. Our results indicate unique elements or a combination leading to recognition. Born-blind participants were able to identify stimuli based solely on their prior tactile experience of the actual objects, the majority being depictions of objects with insignificant thickness. Mirroring hand movements for symmetrical shapes were observed. A broader classification followed by deduction appeared as a common strategy of exploration. These insights impart improved understanding and evaluation of tactile graphics.