Recently, many tactile guide maps have been installed at various public facilities. Tactile guide map designers have used raised dot patterns to express drawings on a tactile guide map. However, we are lacking quantitative data regarding raised dot patterns for the design of easily understandable tactile maps. In this study, we investigated the influence of dot distances on discrimination of dot patterns used in tactile guide maps by conducting an experiment to find highly discriminable combinations of dot patterns by comparing pairs of dot patterns. The results showed that combinations of dot patterns with a larger difference in dot distances had higher discriminability. When the differences were the same, the combinations of wider dot distances had lower discriminability. Dot patterns with more than 5.0 mm differences in dot distances were highly discriminable for sighted persons, whereas those with more than 4.0 mm differences were highly discriminable for blind persons.
