Task 6 Flashcards
Commissurotomy
- dissecting corpus callossum
- epliceptic seizures can be controlled through that, but there are some psychological effects
split-brain research: unilateral testing
1) ask to identify objects by touch alone (inside box)
- right hand: naming possible, left hand = no naming but still knew what left hand felt bc. could shot how to use it (e.g. spoon)
2) Projection tachistoscope (T-scope) to lateralise visual stimuli
- focus on central cross, picture shown on either left or right side + cross-model selection procedure
- RVF = naming
- LVF = no naming but could select matching object with left hand
- > right hemisphere knows and understands concept
- when nude shown to LVF, couldn’t name it but showed embarrassment
- > right hemisphere initiated automatic emotional reaction
- left hemisphere didn’t know what had ben seen but it tried to interpret the emotional reaction
Visuospatial superiority of the RH
- subject is required to use a set of colored blocks to construct a pattern that matches a sample pattern shown in a picture
- > can construct the correct block pattern quickly and easily using their left hand (right hemisphere) but find it difficult/impossible with right hand (left hemisphere)
- one could argue for a manipulospatial superiority of RH: limited to tasks that require some sort of manipulation of objects in space, construction, tactile recognition
Face recognition - right hemisphere superiority
- chimeric figures test: flash composite pictures of faces (each half from different faces) on T-scope
- > PP had to choose the face they had seen from set of 4 faces
- pointing response controlled by RH: patients choose face that matched left half
- when responding verbally -> faces that matched right half of the chimeric face
-face-matching performance was better for right-hemisphere control
visual completion and split brain
-patients subjectively perceive unified whole faces when in fact they have only seen half of the face
the question of dual consciousness
- does commissurotomy produce 2 centers of consciousness?
- > focuses especially on the right hemisphere, since the left one is perfectly capable of introspective verbal report
Other-minds problem
-for the left hemisphere in a spilt brain, the right hemisphere is an other mind
Interactionism theory consciousness
-2 separate centers of consciousness are created since holistic neural activities are now separate
Eccle’s view
- language centers do not produce consciousness, they receive knowledge from immaterial consciousness and make IVRs about it
- > IVR is used as most useful indicator, but not the only one
Sperry’s view on dual consciousness
- intelligent behavior (behavior adaptive to current situation and controlled by flexible thought processes rather than reflexes)
- > as evidence to infer consciousness
- research of sperry supports dual consciousness
- RH shows intelligent behavior and self-awareness
Evidence for intelligent behavior in the RH - cognitive tasks
- intelligent action is usually related to conscious verbal thinking (left hemisphere)
- but it can also follow from thinking in visual-spatial images, (right hemisphere)
- e.g. picture of horse was flashed to patients right hemisphere
- asked what he saw -> he said nothing
- asked to draw what he saw -> left hand drew a horse
- > right hemisphere followed instructions and carried out the task, independent of the left hemisphere
evidence for conscious thinking in the right hemisphere - volition and the alien hand
can the right hemisphere initiate voluntary actions on its own initiative, independently of instructions from an experimenter or the left hemisphere?
Alien hand - independent actions of left hand, some of which seem to show conflict between the left and right hemisphere
