Giulio Tononi, a University of Wisconsin psychiatrist and neuroscientist, invented the Integrated Information Theory of consciousness. Online in Scientific American last Friday, he published an excerpt of a new book, titled “PHI: A Voyage from the Brain to the Soul,” in which he expounds his ideas.
“Consciousness lives where information is integrated by a single entity above and beyond its parts,” he writes in the subheading of the published chapter. To demonstrate where consciousness does not reside, he considers the sensor of a digital camera and its array of millions of pixel-generating photodiodes. The sensor produces the bits of information from which a conscious image can be constructed, but it does not create that consciousness itself.
As another example, Tononi imagines a row of men. If each is whispered the word of a single sentence, each man may think of that word, but “nowhere will there be a consciousness of the whole sentence,” Tononi writes. And in another passage that brings to mind the split-brain experiments of Roger Sperry, Tononi considers a brain severed into its hemispheres at the callosum. Each half brain can be conscious only of what it observes, but the integrated consciousness, which almost all humans possess and which combines the two observations, does not exist.
The core of Intergrated Information Theory is the identification Tononi makes of consciousness with “the information generated by the whole above and beyond its parts,” which he calls “integrated information.” Using a measure of information derived from information theory, he assigns this bonus quantity of information the symbol ?. In the case of the men in a row, ? is the quantity of information that corresponds to the meaning of the sentence, which does not emerge until each man speaks his word.
Perhaps Tononi’s theory may be helpful by pointing out that consciousness is something that holds information. The theory may also make intelligible the notion that consciousness is not an all-or-nothing thing, but varying degrees of consciousness can exist. However, I do not think he has succeeded in explaining what consciousness is. In particular, I think he has left as mysterious the ideational and non-material nature of consciousness; and he does explain the connection of non-material consciousness to the material brain.
This connection of idea and matter, in my view, is fundamental to the universe. It is described in quantum mechanics, that most fundamental theory of reality, as the connection between wavefunction and particle. To every material particle in the universe — and therefore to every material object — there corresponds a mathematical entity called a wavefunction (or, alternatively, a state vector). But because a wavefunction is a mathematical thing, it is therefore an idea — an element of consciousness. A wavefunction is one side, the ideational side, of any entity, the other side of which is the material side. Wavefunction and particle — idea and object — are two alternative descriptions of the unitary wholeness of any existing thing.
The notion that consciousness corresponds to wavefunctions — that the mind, for example, corresponds to the wavefunction of the brain — is helpful when considering the men standing in a row, each thinking one word of a sentence. If they were to announce their words to the whole group, then all would know the whole sentence and comprehend its meaning.
This is how the wavefunctions of their brains would behave, too. When information is exchanged between objects (i.e., when photons pass between them), the wavefunctions of those objects become entangled, and to some extent merge together (overlap) as a single wavefunction. Thus, when the men exchange the information of their words, the wavefunctions of their brains entangle and overlap to a degree. Their individual brain wavefunctions come to share a mathematical component — a factor, if you will — and that shared component corresponds to the meaning of the sentence.
Perhaps Tononi’s factor ? measures the size of this mathematical component. But I’m not sure whether or not that is the case.