Theories of Consciousness

Question 1

Global Neuronal Workspace Theory

Answer 1

For Global Neuronal Workspace Theory, attention and information reaching the frontal cortex is crucial to have consciousness. From global workspace it has recurrent connections which results in global ignition. (300-400 ms).
Stimulus might be
processed ;
1. Subliminal : it evokes weak and not very deep activation of the cortex. (so for instance little activation in the visual cortex).
2. Preconscious : Stimulus evokes stronger and deeper activation, but because of the absence of attention, the stimulus doesn’t reach the fronto-parietal cortex ‘Global Workspace’.
3. Conscious : Because stimulus is attended, it reaches the Global Workspace ‘frontal-parietal network’
- Global Neuronal Workspace Model has all or none component for consciousness.
- You either see it or not see it. When you report seeing something you have activation in the frontal cortex when you report not seeing it you don’t have activation in the prefrontal cortex.
However with recurrent processing theory it is shown that frontal activity is not necessary for determining whether someone is conscious or not. It is only about reporting. When you eliminate reporting but measure consciousness with other things, you won’t see a frontal activation but neverthless the participant will have consciousness. What differentiates seen from unseen :
- Seen info reaches the global workspace ‘fronto-parietal network’ and have global ignition. (recurrent processes). In recurrent processing theory you don’t need frontal region, also information in the frontal region might be unconscious.
- ‘Frontal Activity is the neural correlate of what subjects report seeing’.
- It has all or nothing component because you either see it(fronto-parietal activation) or not see it(no fronto-parietal activation) and depending on that you are either conscious or not conscious

Question 2

Higher Order Thought Theory

Answer 2

For higher-order thought theory, frontal cortex is also very important.
The theory states that we have first-order representations which are visible in the sensory cortex, memory regions etc..
and these first-order representations need to be re-represented by the frontal cortex. But not not the stimulus itself, the thought of the stimulus gets represented.
So not ‘seeing blue’ but ‘I saw blue’.
The ‘thoughts’ idea was studied with metacognition where people were asked to indicate how confident they are in their answers. Metacognition is about ‘knowing’ what you saw. So having the thought
Meta d’ was calculated.
And indeed regardless of the actual performance, participants’ metacognition dropped when TMS was applied to the frontal cortex.

Question 3

Integrated Information Theory

Answer 3

Starts with axioms(self-evident truths).
1. Intrinsic Existence : I know therefore I am.
2. Composition : consciousness is structured and composed of phenomenological distinctions.
3. Information : Conscious experience contains info, I experience one thing and not the other.
4. Exclusion : It is definite. You experience something at a particular rate etc..
5. Integration : Conscious Experience is an integration.
Amount of integrated information is called ‘phi’.
You need balance to have high phi.
So you need differentiated but integrated information.
They also measured phi by PCI (Perturbational Complexity Index).
Integrated information theory is a structuralist theory not functionalist.
Because you can perform the same functions without having consciousness.
What matters is the structure.
Feedforward processing don’t have consciousness but can perform the functions with more neurons.
So just like recurrent processing theory , integrated information theory claims that we cannot have consciousness with feedforward processing only.

Question 4

Perceptual Interference

Answer 4

Information / Features of a stimuli are no longer independent of each other.
Features interfere with each other therefore, regardless of the the colors having the same wavelength you perceive them differently depending on their surroundings.
Mediated by recurrent processing, so when unconscious no perceptual interference.

Question 5

Perceptual Inference

Answer 5

The information you infer from the visual input goes beyond what is physically there.
Mediated by recurrent processing, so when unconscious no perceptual interference.

Question 6

Cognitive Impenetrability

Answer 6

Conscious visual perception is cognitively impenetrable.
So knowing about visual illusions cannot make you ‘unseen’ them.
You can not perceive the two colors as the same even though they have the same wavelength if their surrounding differs.
So knowing about them being different, doesn’t change your conscious percept of them.
This also illustrates the difference between cognitive functions and consciousness.