Influence of the height of tactile dot on the operational performance of cellular phone

In 2000, a new standard (Japanese Industrial Standard, JIS S 0011) was enacted in Japan. The standard provided the perceptual sizes of tactile dots and bars for use in consumer products. However, the numerical values about these sizes were not determined based on data reliable enough. Therefore, objective and quantitative data for perceptual sizes of tactile dots and bars is required for revising this JIS and for devising other standards. In this study, we focused attention on cellular phones becoming common around the world and evaluated the influence of the height of tactile dots (0.0, 0.1, 0.3, 0.5 and 0.7 [mm]) on the operational performance of cellular phone. In this experiment, each 20 sighted younger and older participants, whose hand was covered by a curtain, was asked to operate cellular phones with tactile dot on its key 5 and without tactile dot. Both groups performed better with a tactile dot than without it. However, with a dot height of 0.7 mm, participants felt significant pain. We determined that there is an appropriate range of the height of tactile dot that improves the operational performance of cellular phones.