3.2.4. Interaction Design

Since there is no standard for interactive relief interfaces, and users are likely to lack previous experience with them, it is important to carefully design the interaction so that using the IMG is intuitive and easy to learn. A session with the IMG starts with the user already located in front of the display. The first task is to wear the exhibit's headphones. The exhibition stand only has a label in Braille inviting the user to wear the headphones and indicating their location. This is a barrier for blind and visually impaired people with limited Braille literacy. While it is possible to trigger a speaker to inform the user about the location of the headphones using a proximity sensor, from our user test experience, just verbally informing the user one time and maintaining consistency on the location is enough for users to find and wear the headphones independently across different exhibition stands. In our prototypes, we maintained consistency, by placing the headphones hanging on a hook at the right side of the exhibition display.

The interactive session with the IMG starts when the user either touches anywhere on the relief or presses the "Instructions" physical button on the surface to the right of the artwork relief model. At the beginning of the session, the user listens to a short instruction recording that suggests exploring the relief using both hands. Then, it instructs the user to double-tap to hear more localized detailed information about any point of interest in the relief model or triple tap to listen to localized sounds. The recording also introduces the functionality of the other two physical buttons on the surface. The "General description" button provides general information about the artwork. The "Audio Speed" button changes the speed of the audio narrations. The "Instruction" and "General description" narrations can be interrupted any time another button is pressed or by double or triple tapping on the relief model. This is intended to give freedom to the user to skip the narration if desired.
