You can study consciousness, but not scientifically. The "trick" is that, though you can't make a scientific instrument to detect or measure consciousness, you do have one "instrument" to use: your own consciousness. For example, two people can "merge" and experience themselves as one.
That's unsubstantiated. Arguably, an ability of a person to play any specific multiplayer game at a specific time can be reasonably thought as a measure of consciousness. Then a simple ranking can be used to assign a number.
It is a good theory as it clearly works with drugs, sleepiness, etc
