Saturday, June 18, 2005
Did Terry Schiavo Have Blindsight?
During Terry Schiavo’s dehydration, her friends and family members who did not want her killed frequently used video of her watching and apparently recognizing things in her field of view to prove that she was not in a persistent vegetative state. The autopsy of Ms. Schiavo indicated on page 8 of the attached neuropathology report, however, that she had damage to her occipital lobe that would have rendered her blind. This seeming contradiction bothered me. It is possible that people who watched the video were seeing a pattern in her behavior that wasn’t really there, perhaps because they wanted to see it. Still I wonder if there isn’t another explanation of her behavior: blindsight. Blindsight occurs sometimes when people have functioning eyes, but brain damage that prevents them from converting the nerve impulses from their eyes into images, just as the autopsy indicates Ms. Schiavo did. A person with blindsight cannot consciously see objects the way a normal person can, but the nerve impulses from their eyes are still processed by other portions of the brain. Wil McCarthy devoted an article in his Lab Notes column to the subject. Apparently blindsight sufferers can not look at a crowded room and describe it, but they could navigate from one end to the other without bumping into anything. Could Ms. Schiavo’s apparent tracking of objects in her visual field have been due to blindsight? I don’t know. If anyone is familiar with blindsight, I’d be interested in their opinion.