Wednesday, September 27, 2006

Purkinje on Visual Experience with One's Eyes Closed

Johann Purkinje [Jan Purkyne] was a leading figure in early 19th century physiology, and his descriptions of visual experience were discussed extensively by late 19th century introspective psychologists. However, I haven't been able to find English translations of his work. In connnection with my recent thoughts on our visual experience with our eyes closed, I was particularly intrigued by the respectful citations of his work on this topic by introspective psychologists such as Hermann Helmholtz and E.B. Titchener. So I decided to struggle through some Purkinje in German. In the Underblog, I've posted amateurish translations of a few passages.

A few points of interest about the translated passages:

(1.) Purkinje claims to see a chessboard pattern of squares when his eyes are closed and he's facing toward the sun (as well as in many other conditions). He claims that this experience "was noticed by most individuals with whom I made the experiments" -- so much so that he thinks it must derive from general conditions in the human organism. Yet I don't seem to have such an experience in those conditions; nor has anyone in any condition, whom I've asked about visual experience with their eyes closed, reported such a chessboard pattern to me.

(2.) He makes an interesting point about the difficulty in finding the borderpoint of the visual field with the eyes closed (cf. my post on the limits of the visual field with respect to nasal-side phosphenes).

(3.) The portrayals of afterimages (with the exception of what is now called the "Purkinje afterimage") are two-dimensional -- a point about which he is fairly explicit in Section XXVIII (cf. my post on whether images are flat).

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