Visual Awareness. Awareness Philosophy

Transcription

1 Visual Awareness Jeff Holliday Awareness Philosophy Mind-Body problem what is the relationship and where is the boundary between the physical events in our brain and the corresponding mental phenomenon. Dualism the idea that consciousness and our bodies are two separate, but related entities. 1

2 Cartesian Dualism The idea that our consciousness is a real substance, but not defined by physical properties. Our bodies are part of the world that we only perceive through this extra-physical substance. Events in the physical world affect our mental state and vice versa. Idealism There is only one entity Monism Idealist there is no physical world, only a shared hallucination between everyone. (only a mental world). Materialist every aspect of our awareness is explainable by a physical process, we just are unable to explain it yet. 2

3 Behaviorism Studying psychology and mental-states is irrelevant. Every psychological or conscious state is somehow manifested through our (physical) behavior. John is hungry (wrong) John has a propensity to engage in eating behavior in the presence of food (right). Functionalism Mental state is defined by starting state, environmental conditions (input), organismic behaviors (outputs), and mental state transitions. Very mathematical formulation of consciousness. Multiple realizability A human brain could be constructed out of any device that can do the same things as neurons. The brain roughly equates to a computer 3

4 The Problem of Other Minds How do we identify other conscious beings. (especially w/o a good definition of consciousness) How can we be sure those around us are conscious Each of us is secluded to our own awareness, unable to even describe most of it. Inverted Spectrum Argument If two people experienced colors differently, how would they ever know? This is possible if a person has their L and M cone pigments reversed. Because our experience of color is subjective and cannot be articulated, we would never know 4

5 Split-Brain Patients Patients that have their corpus callosum severed experience very little change in consciousness. Blindsight phenomenon found in patients with limited visual fields. While they report that they have no vision on a particular side, they show an ability to guess extremely accurately what they are being shown on their blind side Due to visual information being transmitted through multiple pathways in the brain. Subliminal Perception The brain will process information below the threshold of awareness. Advertisers often attempt subliminal advertising. A color name was flashed (fast enough to be under threshold of awareness), and then a color was presented. Subject correctly named color faster if the name was consistent with the color presented. 5

6 Inattentional Blindsight Similar to subliminal perception. Events that are not paid attention to (but still seen) fall below threshold of perception but are still present in the mind. Subjects were given an unrelated task, and during task shown briefly the word FLAKE. After completing tasks, subjects were asked to complete FL _ with the first word that came to mind. Subjects shown the word earlier completed with FLAKE 40% of the time, while the others only at 4%. Theories of Consciousness Activation assumption awareness is the result of the firing (activation) of neurons in our brains Functional approach consciousness is an algorithm executed by firing neurons Physiological approach different locations and neuron types firing create consciousness 6

7 Physical approach to consciousness Consciousness arises from a property of matter that is not understood by physical science. Taken to the extreme level (panpsychism), all matter is conscious. Proponents of this theory say the answer may lie in quantum mechanics. Functional Architecture Theories - STM STM (short term memory) our consciousness is composed of the current contents of our STM. LTM elements can be retrieved (much like CPU cache/ram). Activation based refinement Each mental element has a current status, which is elevated every time it is accessed. The MRU set compose our STM and consciousness. 7

8 Functional Architecture - Attention Our consciousness is the contents of our immediate attention plus tangentially related items. Good metaphor spotlight. Bright center with fading fringe. Theory has trouble reconciling selective awareness (which side of the cube we see ) Working Memory Theories Consciousness works similarly to how a computer OS works many distinct processes each with a specialized purpose. Processes communicate through global workspace (shared memory). Works well to explain tasks that become second-nature (like driving). 8

9 Activation Threshold Theory Consciousness arises from neural activity passing a certain level whether it be amount, duration or both Simple model explains subliminal perception well. Conflicts with blindsight removing visual cortex should remove all visual awareness Cortical Hypothesis Theory Consciousness resides completely in the Cortex Strong biological (evolutionary) argument - species with more developed cortices show more perception/consciousness. Non-cortical brain parts are very similar to other, less developed mammals (even those who show much less perception). 9

10 Crick/Koch Conjectures Refinement of the Cortical Hypothesis Theory Concerns neural correlate of consciousness 1 lower layers layers 5 and 6 of the visual cortex give rise to visual awareness 2 40hz the signature of neural consciousness is firing near 40hz 3 frontal lobes the most likely area in which neural correlates of consciousness might exist are the frontal lobes. Also speculated that consciousness must include a reverberatory circuit that echoes previous neuron firings ERTAS Extended Reticular-Thalamic Activating System Utilizes the Working Memory Theories (brain like OS). Hypothesizes that different areas of the cortex are the specialized processes, shared memory is the reticular activating system, and IPC is performed by the thalamus. Great theory, largely untested 10

11 Scientific Progress Parallels The problem of consciousness is very much a mystery. A parallel can be seen in the progress of the discovery of DNA and cell replication. Gregor Mendel Watson/Crick We are in the pre-mendelian phase 11