Originally published April 2, 2018
Here are two excerpts:
Understanding consciousness better would solve some urgent, practical problems. It would be useful, for instance, to know whether patients locked in by stroke are capable of thought. Similarly, one or two patients in a thousand later recall being in pain under general anesthesia, though they seemed to be asleep. Could we reliably measure whether such people are conscious? Some of the heat of the abortion debate might dissipate if we knew when and to what degree fetuses are conscious. We are building artificial intelligences whose capabilities rival or exceed our own. Soon, we will have to decide: Are our machines conscious, to even a small degree, and do they have rights, which we are bound to respect? These are questions of more than academic philosophical interest.
IIT doesn’t try to answer the hard problem. Instead, it does something more subtle: It posits that consciousness is a feature of the universe, like gravity, and then tries to solve the pretty hard problem of determining which systems are conscious with a mathematical measurement of consciousness represented by the Greek letter phi (Φ). Until Massimini’s test, which was developed in partnership with Tononi, there was little experimental evidence of IIT, because calculating the phi value of a human brain with its tens of billions of neurons was impractical. PCI is “a poor man’s phi” according to Tononi. “The poor man’s version may be poor, but it works better than anything else. PCI works in dreaming and dreamless sleep. With general anesthesia, PCI is down, and with ketamine it’s up more. Now we can tell, just by looking at the value, whether someone is conscious or not. We can assess consciousness in nonresponsive patients.”
The information is here.