The Psychomotor Vigilance Task (PVT) is a validated reaction time (RT) test used to assess aspects of sleep loss including alertness and sleepiness. PVT typically requires a physical button to assess RT, which minimizes the effect of execution time (the time taken to perform a gesture) on RT. When translating this application to mobile devices, a touchscreen version is useful for widespread in situ sleepiness assessments to produce more ecologically valid data. We describe the Android-based implementation of a touchscreen version of PVT, called PVT-Touch. In an evaluation (N=20), we compared four different touchscreen input techniques to a physical button: touch down, finger lift, finger tilt, and goal crossing. We found that touch down was comparable to the physical button approach used in traditional PVT in execution time and in several measures associated with sleepiness, and was preferred by most participants. We also found that finger lift may be a more precise but less intuitive measure, which may warrant further study.