This is a Brief Psychomotor Vigilance Test (PVT-B) based on Mathias Basner's paper published in 2011. While making this test, I strongly felt that this could be made as a Whac-A-Mole mini game. Why not?
I tried to make this app as scientific as possible. I strictly followed the original paper's design, which means that a RT between 100 ms and 355 ms is considered success. The test takes exactly 3 minutes. However, please note that smart phones have input lags. This app takes the input lag into consideration, and set the default value to 47 ms. You can change that in settings if you somehow know your phone's input lag.
The original PVT test can only tolerate an input lag of about 10 ms, which means that this app may not be scientific enough to be used in serious researches. Use the data with caution!