Monday, February 29, 2016

Chicken shit and the Progress of Man

Uhm, maybe we don't!
Michael Gazzaniga has spent a career studying split brain patients.  I've previously mentioned his book Who'se in Charge: Free Will and the Science of the Brain. Last week he had a short and entertaining version of his thesis in the New York Times's The Stone series. It's an interesting read. Take a look.

I want to focus on a question Gazzaniga raises for me: what is the connection between perceptions that our brain can articulate and perceptions (and feelings and emotions) that we cannot articulate? What is the connection between chicken salad and chicken shit?

Gazzaniga is describing a trip to a conference in Paris in 1981 where scholars met to peer at the long arc of human progress and ask "what kick-started the explosive technological progress we have witnessed recently." For a million years man was stuck in the stone age. Not much changed. Suddenly, 100,000 years ago, man developed language and stone tools became more and more sophisticated. This explosion in "technological" advancement--which has reached vertiginous speed since the industrial revolution--is not limited to physical things. Technological advancement has been manifested in social forces as well, like philosophical and religious beliefs, and social organizing principles like money.

Gazzaniga is interested in understanding the starring role our brains have played in this explosion of technological change. And he comes at this from having studied split brain patients: patients who have a severed corpus callossum.

With a severed corpus calossum the two halves of the brain cannot communicate with each other. Because our language processing happens entirely in the left hemisphere of the brain, information that is absorbed by the right hemisphere of split-brain patients cannot be shared with the left hemisphere. Information gathered by the right brain hemisphere will remain inarticulate. Is the patient "conscious" of the information absorbed by the right brain only? It raises the question "What does 'conscious' mean?"
The corpus callosum
Gazzaniga reminds us how our left brain has an interpretive function. It makes up stories about what it perceives in order to make sense of the world.  Gazzaniga's article alludes to three levels of interpretation: (1) there is the "interpreter" function (what did I just see?); (2) there is the "storyteller" function (how do I understand what I just saw?); and, finally, (3) there are the abstract fictions that allow large groups of people to understand and shape a shared world together--ideas like money, country, politics, and religion.

The "Interpreter:" Active in both hemispheres?

The interpretative function of our brains, suggests Gazzaniga, is active from processing simple perception, to forging our understanding of how we fit into the world, to facilitating technological revolutions (from advances in stone tools, to the airplane, to the organizing principles of money, country, politics, and religion).

1. Gazzaniga and his team flashed a picture of a chicken foot to a split brain patient's left brain (to the right eye only), and a winter scene to the patient's right brain (the left eye only). Because our language processing occurs in the left brain, the patient could readily identify and describe what the left brain perceived--a chicken foot. On the other hand, the patient's speaking left brain could not understand or explain what was shown to his right brain--the winter scene. Did the patient "know" he saw a winter scene, even though he could say nothing of it? Stay tuned...

2. When researchers asked the patient to perform the non-verbal task of simply pointing to an object he found most appropriate for what he had seen, he readily pointed to a chicken with his right hand (controlled by the left brain which had seen and was aware of the chicken foot) AND he pointed to a snow shovel with the left hand (controlled by the right brain). Although by all appearances to an outside observer, and to the speaking left brain of the patient, the patient was unaware of having seen a winter scene--he could nevertheless easily pick out the snow shovel as an appropriate object for what his right brain had in fact observed, the winter scene.

It seems clear, therefore, that the "interpreter" function is not limited to the left brain. It appears that the right brain was able to make a connection between the winter scene and "snow shovel." It would appear this must include a reasoning process along the following lines: "there was a winter scene; a winter scene involves lots of snow; snow needs shoveling; this snow shovel can be used for shoveling snow; therefore the snow shovel is appropriate for what I saw." The remarkable thing is that this reasoning happens entirely subconsciously.  But maybe that is not the correct term.  Gazzuniga says "the right brain does not speak!" It does seem like the patient's right brain was aware of (conscious of?) the winter scene even though it could not communicate this to the "speaking" left brain.

Are we conscious of what we cannot speak?

The dictionary defines "consciousness"  as "awareness of perception." Gazzaniga's split brain patient was able to correctly pick out the snow shovel as an appropriate object going with "winter scene," but when asked what did you see the patient seemingly was unaware of the winter scene. The right brain was aware of the winter scene and could reason about it, but the right brain cannot speak; the speaking left brain knew nothing about what the right brain was fully aware of but could not articulate or share.

It seems correct, therefore, that we can be "conscious" of things we cannot speak of. It seems we can be conscious of things that to all the world, and to our left brain "explainer" we appear to be unconscious of? What is the sum total of things we are aware of but cannot identify or say at any given time?  Now there is a big question. Therein may lay the explanation for a phenomenon like Donald Trump. The Atlantic  recently compiled a list of rationales why people say they support Donald Trump. These are examples of the left brains exercising its "explaining" function. But how many reasons motivate support for Donald Trump among these people that are invisible to their left brain "explainer?"

3. When the researchers asked the patient "Why did you point to the snow-shovel" the patient's speaking left brain made up a story on the spot. Notably, this story is at odds with what the researchers knew to be the true facts--the right brain was aware of the winter scene and had undergone its  "Winter scene--snow shovel" reasoning--but the left brain knew nothing of this. So the speaking left brain made up a story: "I picked the shovel because I saw a chicken foot, and a chicken foot goes with a chicken shed, and lots of chicken shit, .... AND YOU NEED A SHOVEL TO REMOVE ALL THAT CHICKEN SHIT!"

Chicken shit indeed!

Gazzaniga calls this the "explainer" function of our left brain. It tries to make sense of our immediate perceptions or actions. The "interpreter," says Gazzaniga, "is the system that builds our narrative and gives our many actions that pour out of us, frequently outside of the interpreter's awareness, a centrality, a story — our personal story." We all have this function, and we make up chicken shit like this ALL THE TIME. And therein lies the progress of man.


  1. Is the left brain the sole interpreter? Or is it that we have yet to device a method to probe the interpretive capabilities of the right brain? What story would the right brain tell if we asked it to tell us why the two cards chosen were the shovel and the chicken, and let it respond in the form that it is capable of doing?

  2. That's the question I was struggling with, I think. In the example Gazzaniga gives, the right brain is clearly using interpretative skills to make the connection between "snow scene" and "snow-shovel." The right brain was able to remember the snow scene, and make the connection with the shovel later in time.

    In the example it seems what the right brain is doing is less abstract than what the left brain interpreter is doing. The right brain perceived both the snow scene and the shovel and made a (correct) connection. The left brain a) observed the chicken foot, and b) saw the left hand reach for the shovel, but the left brain did not itself see the shovel. So it was a mystery to the left brain why the left hand reached for the shovel--so it made up a story (which we know is not correct).

    Seems to me the chain of inference that the right brain went through (snow scene; lots of snow; needs shoveling; therefore shovel is the object that matches) is pretty complex. If it can do logical reasoning without language, I see no reason why it couldn't do interpretive story-like connections "without language." Or to put it another way, if it can engage in a correct logical inference, I see no reason why the Right brain couldn't engage in an incorrect logical inference every bit as "competently" as the left brain "explainer." It's a fascinating area of study. I wish I knew more.