3.3.2. Participants

We recruited eighteen participants for the study and divided them into two groups. We held the study with the first group of seven participants at an accessible gallery at a social welfare center for blind and visually impaired people. At a later date, we performed the study with the second group of eleven participants at a school for blind and visually impaired people. Participant age ranged from 15 to 52, with an average of 27.7 years. All of the participants had previous experience using tactile graphics and stated having an interest in arts. None of the participants took part in the formative study. Other characteristics of the participants are described in Table 3. All the participants or their legal guardians gave signed informed consent based on the procedures approved by the Sungkyunkwan University Institutional Review Board.


**Table 3.** Characteristics of participants in our Standard Usability Scale evaluation study.

### 3.3.3. Materials and Apparatus

Two sets of test materials were prepared for the usability study. The IMG set is composed of five standing exhibition IMG prototypes similar to Figure 2b. Each prototype exhibits the 2.5D relief model of a distinct artwork from the selection in Figure 3. Since the participants may not had recently experienced visual artworks through tactile graphics, the second set of materials consisted of tactile graphics reproductions of the same artworks and was produced by a designer with extensive experience in the production of tactile graphics and reading materials for blind and visually impaired people. Descriptions of the artworks in Braille were provided side by side with the tactile graphics.

(**a**) (**b**)

**Figure 3.** Usability study IMG artwork models. (**a**) The Starry Night—Vincent van Gogh; (**b**) Dance—Henri Matisse; (**c**) Senecio—Paul Klee; (**d**) Flowers and Insects—Sin Saimdang; (**e**) Hyunsook's House—Kim Yong-il.
