From cognitive psychologist and physicist Yaïr Pinto at Aeon:
We’ve got to admit that split-brain patients feel and behave normally. If a split-brain patient walks into the room, you would not notice anything unusual. And they themselves claim to be completely unchanged, other than being rid of terrible epileptic seizures. If the person was really split, this wouldn’t be true.
To try to get to the bottom of things, my team at the University of Amsterdam re-visited this fundamental issue by testing two split-brain patients, evaluating whether they could respond accurately to objects in the left visual field (perceived by the right brain) while also responding verbally or with the right hand (controlled by the left brain). Astonishingly, in these two patients, we found something completely different than Sperry and Gazzaniga before us. Both patients showed full awareness of presence and location of stimuli throughout the entire visual field – right and left, both. When stimuli appeared in the left visual field, they virtually never said (or indicated with the right hand) that they saw nothing. Rather, they would accurately indicate that something had appeared, and where.
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And there’s more. While the previous model provided strong evidence for materialism (split the brain, split the person), the current understanding seems to only deepen the mystery of consciousness.More.
Actually, it doesn’t deepen the mystery of consciousness so much as it gives us a sense of its depth, a depth well beyond elegant essays introducing the latest speculation.
See also: Human self-awareness without cerebral cortex
and
Post-modern science: The illusion of consciousness sees through itself