Article 2 and other theories of consciousness Flashcards
Phenomenal consciousness
The intuitive feeling, present in all of us that our internal experiences possess exclusive qualities or unique qualia.
Access of consciousness
A conscious experience that we can articulate and report on.
Critique of GNWS theory by Lamme
According to GNWS, there is limited conscious experience available. Conscious access reflects a selection of the sensory input (by attention). This suggests that conscious experience is very limited and not “rich”. If you would see the entire picture clearly in your mind, you would always notice if there was a change but this is not the case. Change blindness.
Conditions of Lamme’s experiment (article 2)
- Working memory condition: The cue to which rectangle changed is either in the first screen or the second one. Subjects perform well if the cue is in the first screen.
- Iconic memory condition: The cue comes inbetween the two stimulus screens. Subjects perform well on this task too.
- Visual short term memory condition: When the inter-stimulus interval is longer than 500ms
Lamme’s conclusion from the 8 rectangle cueing experiment
The visual experience is short-lived and not easily reportable in contrast to a more stable, reportable form of awareness. We are conscious of many inputs but without attention this conscious experience cannot be reported and is quickly erased.
From iconic memory to working memory
Working memory is a stable and robust representation and iconic memory is fragile and easily overwritten by other stimuli. The transfer from iconic to working memory is gated by attention.
Attentional selection is independent of either awareness or memory, but determines whether we go from phenomenal to access awareness or iconic to working memory. Conscious report is a motor output.
Main difference between Dehaene and Lamme on consciousness and attention
Dehaene: Attention gates conscious access (and is thus limited).
Lamme: Attention selects from what is already conscious (and is thus rich). According to Lamme, attention is only needed for reporting and is therefore a consequence of consciousness, not a cause.
How the brain selects one of two outputs based on two stimuli
Stimuli A may be processed more efficiently because it better matches stored synaptic weights (memory processes) or because it is more salient and therefore the associated neural activity is stronger.
Another way the brain selects one stimuli over the other is in a biased state. This is where the processing of a previous stimulus has left a short term trace of activity. The new stimulus associated with the old one now is favoured.
Observations about FFS (Feedforward Sweep), RP (Recurrent Processing) and visual awareness
- Backwards masking of stimuli renders a stimulus invisible if presented shortly after the first. This invisible, masked, stimulus still evokes a FFS. RP is repressed.
- TMS to early visual cortex beyond the latency of FFS renders a stimulus invisible.
- Anesthesia doesn’t affect FFS but inhibits RP.
According to Lamme, visual processing is mediated by FFS, but not accompanied by awareness, that requires RP.
Why there is a crowding phenomenon at higher visual areas.
All stimuli are represented at early levels but at higher levels the RF’s become larger so competition arises between stimuli. Individual awareness of closely spaced items is impaired. Only a few items can reach highest levels.
Meanwhile, early visual areas have started to engage in RP, resulting in phenomenal awareness. Because there is low competition between stimuli here, recurrent processing of mulitple stimuli is possible.
Difference between Lamme and Dehaene regarding brain areas for consciousness
Dehaene: You need frontoparietal activitation for information to reach consciousness.
Lamme: Only recurrent interaction between higher and lower levels of visual processing is sufficient for conscious experience.
Components of consciousness (ITT)
- Existence: Consciousness exists
- Composition: Consciousness is structured
- Information: Consciousness is differentiated (each experience is differentiated from other possible experiences)
- Integration: Consciousness is integrated/unified (irreducible to its components)
- Exclusion: Consciousness is definite (each experience excludes other experiences
Phi value (ITT)
Quantification of richness of experience. High phi means that information integration is functionally specialized and functionally integrated.
Higher order theories of consciousness
- Neural states of first-order networks are viewed as nonconscious
- Representations are conscious when they are “re-represented” by the higher-order network involving areas of the prefrontal cortex - known as metacognition.
- First-order and higher-order processes represent information in a different format.
