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Part II: Page 3 of 10 |
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This strange observation led Roger Sperry among others to start a series of tests with these patients. E.g. he asked them to keep their sight focused on a dot in the middle of a screen, whereupon he for a short time would show a picture in one half of the screen. In this way only one half of each eye would see the image, and because of the way the eyes are connected to the brain an image in the left side of the screen would only be seen by the right brain hemisphere. And an image shown in the right side of the screen would only be seen by the left hemisphere. In a split brain patient that is. For the rest of us the crossing nerve-connections compensates such that both hemispheres can see the whole field of vision.
The principle is illustrated here: |
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The patient were instructed to tell what he saw on the screen and select an image from several possibilities that would match the one on the screen. If, for instance, the screen showed a leg of a hen, the patient would say he saw the leg of a hen and point to the hen. Quite normal. |
