When the corpus callosum is severed (cut), this can result in patients experiencing 'two consciousnesses,' but only when the information perceived by the left and right eye is different - i.e., the left eye can't see what the right eye is seeing and vice versa. Why does this phenomenon of 'two consciousnesses' arise in these patients in this particular circumstance? Because the corpus callosum's key role is:
a) to transmit information between the left and right hemispheres. When severed, the left and right eye transmit information to only one hemisphere each. So each hemisphere receives different information, resulting in being of two minds or two consciousnesses.
b) to transmit information to the left and right hemisphere. When severed, the left and right hemispheres become cross-wired, so now the left eye projects to the right hemisphere and the right eye projects to the left hemisphere, rather than the right eye to the right hemisphere and the left eye to the left hemisphere.
c) to produce the egocentric frame of reference, and without this brain area, people lose their sense of one continuous self, and a single consciousness splits into two.
d) to produce the object-centered frame of reference, and without this brain area, people lose their sense of object permanence, resulting in a conflict in consciousness and a split into two consciousnesses.