nautil.us | The Integrated Information Theory of consciousness derives a mathematical calculus and gives rise to something known as a consciousness meter, which a variety of clinical groups are now testing. If you have an anesthetized patient, or a patient who’s been in a really bad traffic accident, you don’t really know if this person is minimally conscious or in a vegetative state; you treat them as if they’re conscious, but they don’t respond in any meaningful way.
How can you be sure they’re conscious?
You’re never really sure. So you want a brain-based test that tells you if this person is capable of some experience. People have developed that based on this integrated information series. That’s big progress. The current state of my brain influences what happens in my brain the next second, and the past state of my brain influences what my brain does right now. Any system that has this cause-effect power upon itself is conscious. It derives from a mathematical measure. It could be a number that’s zero, which means a system with no cause-effect power upon itself. It’s not conscious. Or you have systems that are “Phi,” different from zero. The Phi measures, in some sense, the maximum capacity of the system to experience something. The higher the number, the more conscious the system.
So you could assign a number to everything that might have some degree of consciousness—whether it’s an ant, a lizard, bacteria, or a vegetative human being?
Yes, you or me, the Dalai Lama or Albert Einstein.
The higher the number, the more conscious?
The number by itself doesn’t tell you it’s now thinking, or is conscious of an image or a smell. But it tells you the capacity of the system to have a conscious experience. In some deep philosophical sense, the number tells you how much it exists. The higher the number, the more the system exists for itself. There isn’t a Turing Test for consciousness. You have to look at the way the system is built. You have to look at the circuitry, not its behavior, whether it’s a computer or a biological brain. This has now been tested and validated in many patients, including locked-in patients who are fully conscious, people under anesthesia who are not conscious, people in deep sleep, and those in vegetative states or minimal-conscious states. So the question now is whether this can be turned into something practical that can be used at every clinic in the country or the world to test patients who’ve just been in a bad traffic accident.
Obviously, there are huge implications. Do you turn off the life-support machines?
First, does the patient suffer or is nobody home anymore? In the famous case of Terri Schiavo, we could tell the brain stem was still functioning but there wasn’t anybody home. Her consciousness had disappeared 15 years earlier.