A comparative evaluation of sliding contact tactile systems displaying braille and raised print

BACKGROUND: Access to low-cost tactile displays that allow sliding contact between text and reading fingers remains a challenge for blind and visually impaired (BVI) users. This impedes the widespread learning of braille and tactile reading. Previous work demonstrated a high accuracy in the tactile reading of braille and raised print presented at varying refresh rates. OBJECTIVE: This work compares the most suitable spacing between embossed characters on a sliding contact tactile display for the accurate reading of words. METHODS: Two discs, differing in inter-character spacing (ICS), embossed with braille on one side and raised print on the reverse side are used here. MNREAD sentences are read for a period of 5 minutes by 17 participants, who are visually impaired, using both discs. RESULTS: The results show that an ICS of 8 mm is sufficient for reading braille with a low percentage error rate of 6.4. However, an ICS of 8 mm does not allow similar rates while reading raised print. CONCLUSION: The results presented here will be relevant towards the research that works towards the design of economical sliding contact tactile displays for BVI users.