Influence of size of tactile raised Arabic number characters on their perceptibility with a focus on the effects of age in visually impaired and sighted persons

Abstract

Tactile raised characters are useful in creating accessible designs for the benefit of people with acquired visual impairment. For instance, tactile raised characters are used on elevator buttons and television remote controls as an assistive tool based on the philosophy of accessible design. However, sufficient reliable data on the appropriate size for perception of such characters are not available. In this study, we investigated the influence of the size of tactile raised Arabic number characters (0 through 9) on their perceptibility using two experimental designs. One experiment involved young and old individuals with normal vision who were unfamiliar with the systems intended for people with acquired visual impairment, the other experiment was for young and old visually impaired persons. The tactile raised characters were presented one by one in random order using our developed experimental apparatus. There was a correlation between the size of the tactile raised characters and their perceptibility. This knowledge will be useful in discussing revisions to the Japanese Industrial Standard regarding tactile raised characters or in formulating new guidelines pertaining to tactile substitution tools.