Task 6- Consciousness Flashcards
What is a split brain?
Commissurotomy: surgical transection (cutting) of the corpus callosum (=important for communication between right and left hemispheres)
What is the ‘other minds’ problem?
to left hemisphere, the right one is an “other mind”; can only make inferences based on emotional reactions and behavior
–> Is the right hemisphere conscious?
What is the criterion/bridging principle for C according to Eccles?
- IVR (Introspective verbal report)
- -> Right hemisphere is not conscious
What is the criterion/bridging principle for C according to Sperry?
-Dual C?
- Dual C -> two separate C’s if split brain
- bridging principle: intelligent behaviour
- unified C if intact (-> Emergent interaction theory)
What is the original criterion/bridging principle for C according to Gazzaniga?
- Dual C?
- What is his argument about C based on?
- IVR-> one consciousness
- bridging principle: language ability
- argues that right-hemisphere consciousness is rare in split-brain patients, and that when it occurs it is highly correlated with the presence of language abilities in the right hemisphere!
- -> based on patient P.S. -> could not speak but arrange Scrabble letters
How did the observation of an ‘alien hand’ support evidence for C in the right hemisphere?
- alien hand -> intelligent action
- spontaneuous, voluntary action from left hand would support RH C
- sometimes left hand does smth (slammed a drawer while right hand wants to get a pair of socks from that drawer)
What is cross-cueing and how does that support evidence for C in the RH?
-inadvertent cross-cueing: left hemisphere interpreting responses that were made spontaneously but unintentionally by the right hemisphere
-e.g. LH can report what RH has seen or felt
-e.g. ability to name color patches: when making mistake, head chuckled, right hemisphere could hear answer, changed his answer -> emotional reaction or deliberate cue of right hemisphere?
==> RH: conscious, independently of LH
How does visual processing works?
- General principle: left occipital cortex sees the right visual field (RVF) (=are to the right of the fixation point)
- RVF -> seen by left parts of eyeballs -> left parts of eyeballs get processed by left hemisphere
Which functions are primarily in the left hemisphere (=LH)?
o Language understanding and production -> cortex slightly thicker
o Superior at verbal and conceptual tasks
o Self-recognition
–> better at recognizing different faces
-> has been called “dominant hemisphere”
Which functions are primarily in the right hemisphere (=RH)?
o Spatial construction
o Superior at recognizing similar faces
o Manipulo-spatial superiority
o Drawing
o Making causal inferences and temporal discrimination
o Superior at recognizing musical melodies
o Creativity
Are the differences between right and left hemispheres absolute?
No, they are relative
What does the ‘Left brain, right brain mania’ say?
more accurate view is that in the normal brain different styles of thinking (rational, intuitive, imaginative) are complex processes that involve the interaction of different subsystems (or modules) within each hemisphere as well as interactions between the right and left hemispheres
How does the experiment with z-lenses support evidence for C in RH?
- Z-lens limits vision to left visual field (-> RH)
- Self-recognition in right hemisphere -> cannot verbalize it (cause that’s only possible in LH)
- emotional reaction (laughing) and RH trying to speak/articulate -> enable LH to speak/ say correct answer
Which two psychological constructs can be seen when blocking the right visual field with z-lenses?
Self recognition and social values
Why is split-brain research so hard?
- Most people with one had a severe epilepsy
- Only few split-brain patient
- Split brain subjects show considerable variability among themselves
What is the object identification task?
Naming object by feeling it
What are the results of the unilateral testing/object identification task?
- LH knew what object the right hand had felt and named it accurately
- RH could not name what the left hand had felt
- -> right hemisphere knew what the left hand had felt because it could show how to use it e.g. while blindfolded, subjects could use the left hand to show how to use a spoon or a paintbrush, using appropriate motions
What is the T-scope test?
objects only presented a short time so that both visual fields do not process it
What are the results of the T-scope test regarding the two hemispheres?
- left hemisphere can name what it sees
- the right hemisphere knows what it sees, but cannot name it -> could read common nouns, and select the corresponding object by touch and can initiate an emotional reaction
What is the block-design test?
subject is required to use a set of colored blocks to construct a pattern that matches a sample pattern shown in a picture
What are the results of the block design test?
- construct the correct block pattern quickly and easily using their left hand (RH)
- find the task difficult or impossible with their right hand (LH)
Which hemisphere is superior in what according to the block design test?
manipulo-spatial superiority of RH
Which hemisphere is better at recognizing faces and under which circumstances?
- RH’s superiority at face recognition was limited to tests involving similar faces, in which it was hard to discriminate between the different faces
- LH did a good job when faces were very dissimilar
What does Gazzaniga mean with modules?
independent functional units that can receive information, compute, store and retrieve memories, trigger emotional reactions and produce behaviour
What is an ‘interpreter system’ according to Gazzaniga?
- special module
- tries to interpret the diverse actions of the various modules, to explain why they occurred, and to fit them into the narrative sequence of events of our lives and conscious experience
Where is Gazzaniga’s ‘interpreter system’ located according to him?
only in left hemisphere
What is eventually Gazzaniga’s bridging principle after conducting his experiments?
- presence of interpreter system
- C: associated with activity of interpreter system
- ->Normally occurs only in LH, but it is not the language system itself
Which kind of C is Gazzaniga’s interpreter system similar to?
similar to the idea of reflective consciousness
What does the evidence eventually suggests with respect to which kind of C do the hemispheres have?
- both LH and RH have primary consciousness
- reflective consciousness may be limited to the LH
What does the partial- consciousness model say?
- only LH gives rise to C
- RH only processes information in an unconscious manner
- RH might prime LH towards certain behaviour, but this will only affect C after it has been molded and interpreted by LH
What is the split-consciousness model?
- by Sperry
- in a split-brain patient each hemisphere has its own C; each has its own sensations, perceptions and cognitive processes
What are the 5 hallmarks observed in split-brain patients?
- Response * visual field interaction (when stimulus is presented to LVF , patient can only respond adequately with left hand)
- Hemispheric specialization
- Post hoc-confabulations (after actions with the left Hand -> Alien hand)
- Split attention
- Incapacity of comparing stimuli across the midline
Which 3 of the 5 hallmarks exist also in patients with unified C?
hemispheric specialization, post hoc confabulations (e.g. gaps in memory) and split attention
Is there object-based attention in split brain patients in LVF/ right hemisphere?
No
What does the “Conscious unity, split perception model” say about C?
- C is unified in split-brain patients -> are still one conscious agent in control of their entire body and thus feel mostly unchanged
- This one agent experiences entire visual field and controls his/her entire body
- Easy to respond to stimuli anywhere in the visual field, with any response type
How does the “Conscious unity, split perception model” explain differences from healthy patients?
due to unintegrated perception
How does the analogy to an out-of-sync movie relate to a split perception?
perception split because you experience a visual and an auditory stream -> unable to integrate these two streams
How does the “Conscious unity, split perception model” explain hemispheric specialization?
contralateral hemisphere does all the visual processing -> leads to maximal hemispheric specialization
What is the basis for a unified C according to the “Conscious unity, split perception model”?
- Subcortical areas are still unified in split-brain patients
- Functional unity -> when connected to common source (e.g. thalamus); indirect connections
How does the “Conscious unity, split perception model” challenge the Integrated Information Theory?
Integrated information theory -> says that C is split
How does the “Conscious unity, split perception model” challenge the Global Workspace Model?
Global workspace -> headquarter
-implies that partial or split C arises
Does the “Conscious unity, split perception model” challenge the Recurrent Processing Theory?
- local processing -> phenomenal C only
- unified, reportable C: you need both hemispheres
- -> kind of compatible w/ model
