This is not an altered-state-generating test, it's an attentive vigilance test. It's a measurement of "concentration" in its purest sense of "the mind staying with something rather than wandering from it", with the tactile stimulus response serving to quantify concentration. Something like the ratio of "hits : (misses + false positives)" could be used as a scoring formula. A miss would be failing to notice a shift from the baseline tactile stimulus to the altered one within some specified time limit, and a false positive is of course indicating a change when there was none.
It would be something like the concentration training part of the ReWire app, except using touch in the place of sound. There are also formal visual and auditory attention/vigilance testing protocols in experimental psychology, but I've never heard of one that uses touch as the stimulus. Should be interesting. Perhaps even relevant to neuroscience and psychological science, as they move from only studying visual and auditory attention to including other forms of attention.
As for the electrodes... I'm not sure whether or not that would be easier than small vibration-generating motors. Come to think of it, someone could make a smartphone app that uses the phone's vibration to do this, and much like with ReWire, you could touch the screen to indicate when the stimulus changed.
