Computer Feedback in Meditation

Are there any meditation computer feedback programs out there? Like Biofeedback. What could they do? Allow a teacher much insight into a student? Allow a meditator to know when wandering is happening, when subtle thinking is happening or to know when reality is seen directly or with concepts? Would this be a helpful tool to be used all the time, only sometimes or never?-(Perhaps because it creates a duality, it creates aversion, it's unnessasary, it's not in the Pali Canon or anything).