Michael Gazzaniga, who directs the SAGE institute for the study of the mind at UC Santa Barbara, has come out with a book on how the brain gives rise to the mind. He believes that consciousness is not tied to a specific neural network. Various functions that take place in the brain each have intrinsic consciousness. So what is his proof? One line of evidence is that when the cable connecting the left and right hemisphere is cut:
…the left hemisphere keeps on talking and thinking as if nothing had happened even though it no longer has access to half of the human cortex. More important, disconnecting the two half brains instantly creates a second, also independent conscious system. The right brain now purrs along carefree from the left, with its own capacities, desires, goals, insights and feelings. One network, split into two, becomes two conscious systems.
Patients with a lesion in a particular part of the right hemisphere will behave as if part or all of the left side of their world…does not exist!
This could include not eating off the left side of their plate, not shaving…on the left side of their face…not reading the left pages of a book, etc.
It seems that when you lose a capacity, you are not even cognizant of what you’ve lost. You don’t know what you don’t know.
In a section titled “What is it like to be a Right Hemisphere”, Gazzaniga says that you would not notice the loss of the left hemisphere. You would have trouble communicating, because you lost your speech center. You would also lose your ability to make inferences.
“Though you would know that others had intentions, beliefs and desires, and you could attempt to guess what they might be, you would not be able to infer cause and effect. You would not be able to infer why someone is angry or believes as they do.
Not only do you not infer that your neighbor is angry because you left the gate open and her dog got out, you don’t infer that the dog got out because you left the gate open
On the positive side, without a left hemisphere:
You won’t be a hypocrite and rationalize your actions…You would have no understanding of metaphors…
This is interesting also if you look at my prior post in this blog on the causal diagrams of Judea Pearl. He says that the causal diagrams he draws must be similar to how we represent them internally, and yet, Gazzaniga is saying that only one hemisphere has the ability to think about causes.
In a prior post, I mentioned that: “V. S. Ramachandran’s studies of anosognosia reveal a tendency for the left hemisphere to deny discrepancies that do not fit its’ already generated schema of things. The right hemisphere, by contrast is actively watching for discrepancies, more like a devil’s advocate. These approaches are both needed, but pull in opposite directions. ”
So I suppose if you were a right hemisphere, your ways of thinking would be very different than if you were a left hemisphere.
In fact, Gazzaniga gives fascinating illustrations of such differences. Suppose you show a film of a ball coming toward another ball, not quite touching, but the second ball acting as if it was hit and taking off. The left hemisphere of a split-hemispheres patient will fall for the illusion even if there is a delay in the second ball moving, or if the distance is increased between the balls. The right hemisphere eventually sees that it is an illusion. On the other hand, the left hemisphere will solve problems with logical inference that the right hemisphere can’t. It seems that the right-hemisphere can PERCEIVE causality, but the left hemisphere can INFER causality.
Rebecca Saxe at MIT found that the right half brain has special ‘hardware’ to determine the intentions of other people. (This ability is also known as ‘theory of mind”). Based on this finding a former student of Gazzaniga’s Michael Miller, and a philosopher (Walter Sinnot-Armstrong) had the idea of looking at split brain patients to see how each hemisphere evaluated moral responsibility. They presented scenarios such as this one:
If a secretary wants to bump off her boss and intends to add poison to his coffee, but unknown to here, it actually is sugar, he drinks it, and he is fine, was that permissible?
The left hemisphere judges the secretary as blameless, despite the malicious intent, since no harm was done. The right hemisphere would not agree – it would take ‘intent’ into account. But the judgement of the right hemisphere is not available to the left hemisphere, because the communication cable between the hemispheres is cut. There may be some type of communication though – the right hemisphere has a ‘bad feeling’ about the situation, and that feeling is available via older brain areas to both hemispheres. So the left hemisphere may feel impelled to explain its decision.
Gazzaniga writes that even though your experience seems a coherent, flawlessly edited film, it is instead
a stream of single vignettes that surface like bubbles ..in a boiling pot of water, linked together by their occurrence of time.
This raises a question:
Do the bubbles burst willy nilly, or are they the product of a dynamic control system? Is there a control layer giving some bubbles the nod and quashing others?
He gives several options:
- competition. If you bite into bitter chocolate, no module that processes sweet sensations is activated. Bitter information is being processed. If you eat milk chocolate instead, then the ‘sweet module’ is up and running as well, and outcompetes bitterness by a landslide.
- Top down expectation: you are searching for the one person in the crowd with a red flower in her hair
- Arbitrary rules: For instance, if you have been told that low-fat diets are the road to health, then bubbles will come up as you shop for groceries, guiding you to stay clear from various products. If you then read that ‘fat’ is actually good for you, you will get different bubbles.
At one point he also suggests that the ‘bubbles’ are linked by the feelings they engender as well, and a possibility that occurs to me is that the ‘interpreter’ in our brain – an area with the function to make a story out of our thoughts and make sense of our own actions, might also link these experiences.
There is much more to the book.
One analogy he makes that I have not heard before is for the hierarchical sets of layers in the cortex. The analogy he makes is to the screen of a computer. When you interact with a computer, as far as your experience, you don’t interact with circuits and registers and bits, you interact with icons and pictures and words on a screen, using a keyboard and a mouse. The details are abstracted for you. The same goes for the hierarchies of layers in the brain – each layer just passes an abstracted version to the next.
After finishing the book I’m still left with a mystery. Suppose a ‘bubble’ outcompetes all others, and is the focus of my mind. And each bubble has intrinsic consciousness that goes with it. How is that subjective consciousness felt and experienced? Where is the qualia of a bright red sunset? Where is our feeling of 3-D space? What does it mean to feel we are exerting a force, such as a force of willpower not to have dessert? And where does the inner voice come from that says something is wrong with a story you’ve just heard, but you can’t pinpoint yet what it is? Is it a module trying to get into consciousness?
The Consciousness Instinct – Unraveling The Mystery of How The Brain Makes The Mind – Michael S. Gazzaniga (2018)