Usability of Back of Device Virtual Buttons

Back of device touch screen capable game systems have been commercially available since the release of the Playstation Vita in 2012, however the use of these touch screens in games has been limited. With the release of the touch screen lacking Playstation Vita TV, it seemed as though the use of the second touch screen would become even less common as developers produce games with features common to both platforms. Back of device touch was revived with the release of the Playstation 4 with the purpose of mapping DualShock 4 inputs unavailable on the Vita to sections on the back of the device during remote play. This paper seeks to understand the limitations of using back of device touch screens for game input. Four selection tasks involving a total of 30 participants compared the reaction times and accuracy for 13 different back of device touch region layouts. The results found that the usability of the back touch screen on a Playstation Vita was in line with standard game controllers and the performance significantly decreased when 12 or more virtual buttons were present.