Touch the Color Change: Representation of Color Change Using Tactile Grating Patterns

Abstract

We proposed a method representing relative color difference using tactile grating patterns by changing 3 components (i.e., orientation, spacing, and height) and assessed the feasibility psychophysically and qualitatively. Most color expression studies for the visually impaired have focused on a 1-to-1 correspondence between color and tactile patterns. With this 1-to-1 correspondence, a long period of associative learning is necessary, and it is impossible to represent a subtle change of colors. However, the proposed method could enable the effective perception of color changes. Two different experiments were conducted with sighted participants as a preliminary study to examine this method's feasibility and effectiveness. In a psychophysical experiment, participants performed dissimilarity rating tasks to measure how sensitively they perceived orientation, spacing, and height-change of the grating. In a tactile art appreciation experiment, participants appreciated 3 different tactile artworks characterized by 3 different grating components and responded to the questionnaire. The grating's orientation and spacing changes were revealed as effective in tactile dissimilarity perception and expressing color change within an artwork. However, the grating height-change was revealed as it was difficult to perceive the texture changes and had less effectiveness in expressing colors. Among the 3 components, orientation- and spacing-change of the grating were effective for expressing color changes. In addition to art appreciation, this method can be useful in many applications for the visually impaired where the effective expression of color change is required.