Friday, March 27, 2009

Some months ago in December, Chiao recommended to me a book on consciousness, by a person doing philosophy of mind for a career. This particular book is not at all like the other philosophy books I normally read - it was a collection of short reviews on many other books about consciousness. Nonetheless, I decided to try it and see.

I have only finished it very recently as other developments have taken up my time =) .

Because of the anthology structure of the book, the reviewer spent the most part of each piece describing each book under his review, and only a little part assessing his responses to it and marshalling his own philosophical arguments against the book author's arguments. Perhaps this is why I found the collection unsatisfying.

The excerpt I wish to archive on this blog is cited from another book by the reviewer:

A promising line of attack is to approach consciousness by way of the unconscious. There are plenty of clinical cases of processes in the brain that are psychologically real but which have no conscious manifestation. Perhaps the best known of these is "blindsight" [Ref]. In these cases, the brain-injured patient is able to report events occurring in his visual field but he has no conscious awareness of the events. The patient has both eyes intact but has damage to the visual cortex at the back of the brain that makes him blind in one portion of his visual field. In a classic study the patient, DB, is blind in the lower left quadrant. If you think of the visual field as roughly resembling a circle in front of your eyes, then DB can see the right half of the circle and the top part of the left half, but he sees nothing in the lower part of the left half. In one experiment DB's eyes were focused on the center of a screen and Xs and Os were flashed on a screen exposed to the blind portion too quickly for him to move his eyes. He is asked to "guess" what was flashed on the screen. He insists that he can't see anything there, but he guesses right nearly all the time. Such patients typically are surprised at their successes. "Did you know how well you had done?" asked the experimenter in an interview after one experiment. DB answered, "No, I didn't because I couldn't see anything. I couldn't see a darn thing" (p. 24 of Ref).

The Ref is Weiskrantz, Lawrence (1996). Blindsight: A Case Study and Implications. Oxford University Press.

The critical collection of book reviews itself is Searle, John R. (1997). The Mystery of Consciousness. The New York Review of Books.

This page is powered by Blogger. Isn't yours?