*3.1. Experiment Design*

The experimental evaluation was performed in three stages; learning phase, tests, and feedback. Fifteen volunteers of ages between 19 and 29 years took part in the experimental evaluation of the ColorWatch design and prototype. The volunteers were recruited through school notice board announcement, and twelve of them were males while three were females. All of the subjects had normal vision, did not declare any associated cognitive or psychiatric disorders, and they performed the experiments after putting blindfolds on. Firstly, the test subjects were told about the ColorWatch concept, prototype function, and spatial tactile-color associations. The participants were then allowed free time to ge<sup>t</sup> familiarized with the prototype and its function with color identifications. All the colors and their color tones were provided as color sample cards of the size of a quarter of standard A4 size paper each. The subjects were encouraged to use a ColorWatch prototype on real-life objects during the learning phase. The color identification data during the learning phase were not recorded. However, subjects mainly tried to identify colors for table, paper, PC monitor, phone back cover, and their clothes through the tactile interface. After comparing the identifying color with their memory, some of them talked about the challenges PVI might face due to a lack of vision. It was interesting to note that many subjects tried color identifications with blindfolds put on without requirement, once they go<sup>t</sup> familiarized with the prototype. The same color samples were used in the user tests for standardization of the color set for all users. After completing the learning phase, the subjects were then asked to put blindfolds on for user tests. At this point, color cards for all the twenty-four color samples in random order were provided one at a time. The subjects were asked to identify the given color by identifying the tactile pattern from the ColorWatch prototype. The primary color and color tone for the given card and the corresponding identification by each subject were carefully registered, and this procedure was repeated

for all the color samples. The subjects were not provided with feedback during tactile identification tests. Finally, subjects evaluated the usability of ColorWatch, provided any remarks they had, and responded to the qualitative reasoning queries regarding their tactile following scheme and usability evaluations.
