Split-brain vs. Normal People

Split-brain studies imply but do not prove that ordinary people have two
minds. However, there is abundant scientific evidence that demonstrates

jay alfred | brains and realities
the relevance of split-brain findings for ordinary people with intact brains.
In split-brain patients the left brain uses different strategies from the right
brain.
Scientists have found that ordinary people have the same differences in
cognitive abilities between sides as split-brain patients. If an ordinary per-
son is seated in front of a screen and asked to look forward and an object is
flashed very briefly to his right side (i.e. his left brain), he will respond faster
and more accurately if the task involves language. If you flash a spatial task,
for example, asking the subject to identify if a dot is within a circle, he will
perform better when flashed on his left side (or to the right brain).
Ordinary people are also shown to be better at seeing the overall picture
if an image is flashed to the right brain. These studies and others involving
hearing through the left and right ears have been repeated many hundreds
of times in ordinary people, and the findings are consistently similar to
those in split-brain patients. The findings mean that the cognitive abilities
of the left and right brains of split-brain patients are similar to those of or-
dinary people.
PET scans show that even when normal people (with intact brains) talk,
the blood-flow pattern changes in their brains, and there’s more activity
in the left brain than in the right. When they imagine space, the pattern
reverses. One study on occupational preferences in cognitive styles showed
that those who declared English as a major had a greater blood flow in the
left brain (the verbal brain); whereas those who majored in architecture had
a correspondingly higher level in the right brain.1

When all the evidence is sifted and weighed, we are reminded
that our ‘ordinary’ minds are more similar to split-brain minds
than some neuroscientists would like us to believe.
Dr Frederic Schiffer 2
Despite myriad exceptions, the bulk of split-brain research has
revealed an enormous degree of lateralisation, or specialization
in each hemisphere.
Michael Gazzaniga 3