Lecture 1 - Intro + Consciousness
In the exploration of consciousness and free will, research began with: The study of people with brain damage and how they perceive the world.
Consciousness: The state or quality of awareness (thoughts, perceptions, memories, feelings)
State of awareness creates a subjective experience
Medical solution for psychosis, depression, anxiety in the past: Cut it out. Lobotomy.
The split-brain operation: Outdated surgical approach for seizures, cutting corpus callosum: bundle of nerve fibres that connect left and right sides of cerebral cortex.
Cerebral hemispheres (purpose): Critical for the conscious processing of sensory info (sight, sound, touch), as well as motor ability (moving hands in space).
Cerebral hemisphere wiring: Criss-cross; left brain responsible for right side and vice versa.
Corpus callosum role in vision: Joins the two fields of vision, both eyes can see middle but left sees right field and right sees left field. Overlap.
Corpus callosum (purpose): Shares info between hemispheres so that each side knows what the other is perceiving and doing. When cut, the hemispheres cannot communicate with one another but they still send info downwards (to brainstem and spinal cord) for muscular control. Lower brain areas (brainstem, spinal cord) proces sinfo beneath conscious awareness (reflexes?).
History of the split-brain surgery: 26 patients with intractable epilepsy underwent surgery. Doctor claimed it was a success but researchers later revisited and found that improvements were short-lived and cutting the corpus callosum did not do very much (+ or -). Continued with experiments cutting the CC for animals and they found it caused cognitive peculiarities. Surgeries a decade later were successful, seizures reduced and patients felt no different from before. BUT patients reported left hand having a mind of its own, working against their conscious goals. Right hand would fight left. Left hand outside of conscious awareness? What was going on with the right hemisphere? Right hand, controlled by left cerebral hemisphere consistent with person’s conscious intentions.
Vicki: Another split brain patient where left hand fought against right. Issues abated after about a year.
Consequences on vision and touch for split brain patients:
When a split-brain patient closes their eyes and touches a familiar but unidentified object with the left hand, they cannot identify the object out loud
When a split-brain patient sees an image only in their left peripheral vision, processed on the right side of the brain, they cannot verbalize what they see. Split brain patients cannot say out loud something that only the right brain sees.
TAKEAWAY: Split brain patients appear to be unconscious of — cannot verbalize — any stimuli directed exclusively to their right brain.
One hemisphere would take the lead in controlling behaviour.
Localization of language in brain: Language ability located in left cerebral hemisphere. Right has limited language abilities, but keeps “dictionary” of simple phrases/numbers/letters. Left hand (right brain) could also be used to indicate answers to simple questions.
Post-behavioral explanations (split-brain patients): Researchers observed that split-brain patients would come up with explanations for their behavior after the fact. Right brain (motor) often initiated behavior, left brain (language) would generate explanations.
Gazzaniga’s Interpreter Theory: Behavior is fully controlled by unconscious processes, and that the function of our left-brain consciousness is simply to create narratives with the information it has in an attempt to make sense of the world. Therefore, conciousness doesn’t directly influence behavior, not in real time. Consciousness is then storytelling, storytelling requires language, therefore consciousness is located in left brain. Theory went out of favor.
History of thought: Before scientific revolution, people relief on intuition rather than math (earth doesn’t feel like it’s moving). Math and science grew during scientific revolution, and people began to suspect that the world was deterministic. Humans only witness the world unfolding.
Rene Descartes: Rene Descartes questioned lots, like what could we trust. “I think, therefore I am.” What are thoughts and ideas? For him, the act of thinking proved that an immaterial world exists.
Mind-Body Dualism & Cartesian Impasse: Mind is something immaterial that exists outside of body and determinism, but how can the immaterial control the material?
Evolution of thought: Brian evolved, allowing sensing of internal and external world to coordinate movements of organism. Gave rise to thoughts, on top of automatic responses (reflexes). Thoughts do not produce automatic responses. Outside of sensory input or motor output. Thoughts/ideas give meaning, laws of physics do not.
Is the world deterministic?: No inherent meaning in a deterministic world, but our brains construct a world of ideas/meaning on top of the laws of nature. Layer of thoughts and ideas controls the physical laws of nature. Contested theory. Thoughts have influence and power. It is a creative act, allowing abstract ideas which direct and constrain how the organism will act in the future. Allows to theorize about how things might otherwise be. Can construct the future. Breaking determinism.