On the "What" Pathway of Vision and Its Relation to Consciousness
And now, finally, the first of the promised entries inspired by Ramachandran's book, Phantoms in the Brain....
Dr. R. studies all those weird cases of people who have seemingly unique brain problems giving rise to everything from tasting colors to imaginary limbs to not recognizing faces or inability to do math.
For this first entry, I want to cover vision and its relation to the soul or at least consciousness.
Backing way up in my entries, I have talked about Descartes and "Cogito, ergo sum."[1], how the fact that we think consciously implies that we are conscious beings, conscious souls. Now, in some senses, a lobster thinks, but he or she or it is not aware that he/she/it is thinking. If one is not aware of thinking, it is problematic to think that he or she has a self or soul at all.
In an entry after that one, I covered how people perceive, think, and remember, and how it seems to be different for different people, how the "reality" (or better "perception") that each person experiences is different.[2] Yet even so, something is perceived, something is consciously felt, interpreted, and thought about.[3]
This is not the case for all vision.
There is a phenomenon known as "blind sight", which is when someone is complete unaware of seeing something, yet his brain and body respond to it. For example, the person may be blind, never consciously aware of seeing him. His or her reality is completely black. However, nothing at all is wrong with the eyes. Light, color still pass through them, still travel down the optic nerve as electrical impulses. Only a certain part of the brain is damaged, such that the person is never aware any of this is going on. But calculations and such are still made by the functioning parts of a brain. A patient with this defect can still dodge balls that are thrown at them, and avoid walking into objects. It is not because he or she hears the sound of the ball; the ball is seen by the eyes and interpreted by a portion of the brain, only there is no consciousness of it.
But a fully normal human brain has blind sight as well. While we are only aware of what the brain feeds our conscious areas, visual information is going to unconscious areas as well.
There is a pathway through the brain called the "what" pathway or the "ventral stream". It is involved in recognition of visual stimuli. There is also a "where" or "how" pathway, which deals with spatial and manipulative calculations involving vision. If you take monkeys and wipe out there "what" pathway, they seem just like normal monkeys. They do not bump into objects, they know how to grab things, etc. But they do not recognize anything. They have no discernment as to what is food and what isn't, they cannot recognize a ball from another monkey. A pole looks just as sexually-exciting as a female monkey.
This problem has occurred in humans -- though not an entire destruction of the "what" pathway -- with similar problems. These people are not at all blind.
Now the question must be raised about the "self" of a hypothetical human without a "what" pathway. Ramachandran writes:I'd venture to predict that when you woke up the entire world would look like a gallery of abstract sculpture,... No object you looked at would be recognizable or evoke emotions or associations with anything else. You'd "see" these objects, their boundaries and shapes, and you could reach out and grab them, trace them with your finger and catch one if I threw it at you.... But you'd have no inkling as to what these objects were. It's a moot point as to whether you'd be "conscious" of any of them, for one could argue that the term consciousness doesn't mean anything unless you recognize the emotional significance and semantic associations of what you are looking at. [emphasis mine]
Like my lobster above, these poor humans would not know that they were seeing. Would they be conscious at all?
Someone might say, "Now this cannot be right, because blind people are still conscious." Yes, but interestingly enough, it has been shown that blind people dream in images of sorts -- even if born blind.[2] The "what" pathways in blind people are still intact -- even if it is never fed with true visual information from the eyes. Only their eyes are damaged. (Or they operate on blind sight only, which still means they have a "what" pathway.)
I previously modified or extended Cogito, ergo sum to Memini, ergo sum qui sum, "I remember, therefore I am who I am." I think I might now be able to add, Gnosco, ergo possum cogitare, "I recognize, therefore I am able to think."Edit 23.01.07: corrected "self-aware" to read "aware" -- not all conscious creatures are self-aware, but they all have awareness of sensual information
Dr. R. studies all those weird cases of people who have seemingly unique brain problems giving rise to everything from tasting colors to imaginary limbs to not recognizing faces or inability to do math.
For this first entry, I want to cover vision and its relation to the soul or at least consciousness.
Backing way up in my entries, I have talked about Descartes and "Cogito, ergo sum."[1], how the fact that we think consciously implies that we are conscious beings, conscious souls. Now, in some senses, a lobster thinks, but he or she or it is not aware that he/she/it is thinking. If one is not aware of thinking, it is problematic to think that he or she has a self or soul at all.
In an entry after that one, I covered how people perceive, think, and remember, and how it seems to be different for different people, how the "reality" (or better "perception") that each person experiences is different.[2] Yet even so, something is perceived, something is consciously felt, interpreted, and thought about.[3]
This is not the case for all vision.
There is a phenomenon known as "blind sight", which is when someone is complete unaware of seeing something, yet his brain and body respond to it. For example, the person may be blind, never consciously aware of seeing him. His or her reality is completely black. However, nothing at all is wrong with the eyes. Light, color still pass through them, still travel down the optic nerve as electrical impulses. Only a certain part of the brain is damaged, such that the person is never aware any of this is going on. But calculations and such are still made by the functioning parts of a brain. A patient with this defect can still dodge balls that are thrown at them, and avoid walking into objects. It is not because he or she hears the sound of the ball; the ball is seen by the eyes and interpreted by a portion of the brain, only there is no consciousness of it.
But a fully normal human brain has blind sight as well. While we are only aware of what the brain feeds our conscious areas, visual information is going to unconscious areas as well.
There is a pathway through the brain called the "what" pathway or the "ventral stream". It is involved in recognition of visual stimuli. There is also a "where" or "how" pathway, which deals with spatial and manipulative calculations involving vision. If you take monkeys and wipe out there "what" pathway, they seem just like normal monkeys. They do not bump into objects, they know how to grab things, etc. But they do not recognize anything. They have no discernment as to what is food and what isn't, they cannot recognize a ball from another monkey. A pole looks just as sexually-exciting as a female monkey.
This problem has occurred in humans -- though not an entire destruction of the "what" pathway -- with similar problems. These people are not at all blind.
Now the question must be raised about the "self" of a hypothetical human without a "what" pathway. Ramachandran writes:I'd venture to predict that when you woke up the entire world would look like a gallery of abstract sculpture,... No object you looked at would be recognizable or evoke emotions or associations with anything else. You'd "see" these objects, their boundaries and shapes, and you could reach out and grab them, trace them with your finger and catch one if I threw it at you.... But you'd have no inkling as to what these objects were. It's a moot point as to whether you'd be "conscious" of any of them, for one could argue that the term consciousness doesn't mean anything unless you recognize the emotional significance and semantic associations of what you are looking at. [emphasis mine]
Like my lobster above, these poor humans would not know that they were seeing. Would they be conscious at all?
Someone might say, "Now this cannot be right, because blind people are still conscious." Yes, but interestingly enough, it has been shown that blind people dream in images of sorts -- even if born blind.[2] The "what" pathways in blind people are still intact -- even if it is never fed with true visual information from the eyes. Only their eyes are damaged. (Or they operate on blind sight only, which still means they have a "what" pathway.)
I previously modified or extended Cogito, ergo sum to Memini, ergo sum qui sum, "I remember, therefore I am who I am." I think I might now be able to add, Gnosco, ergo possum cogitare, "I recognize, therefore I am able to think."Edit 23.01.07: corrected "self-aware" to read "aware" -- not all conscious creatures are self-aware, but they all have awareness of sensual information