Friday, August 17, 2007

Eyes Closed Visual Experience -- Subject 1

Over the last year, I've been thinking a bit about visual experience with our eyes closed (e.g., here, here, here, here). A few months ago, I started giving volunteer subjects random beepers and having them keep their eyes closed for two hours a day over the course of three days. After each random beep, they were to note whether they had any sort of visual experience in the last undisturbed moment immediately before the beep, and if so what it was. After each day (about 3-6 beeps), each participant came to my office for an hour-long interview.

Subject 1 was a male graduate student in philosophy who expected not to find any visual experience, not even of blackness, with his eyes closed. (On people's differing opinions about the omnipresence or not of visual experience see here.) He distinguished sharply between sensory visual experiences and visual imagery experiences. (To understand that distinction, keep your eyes open and form a mental image of the front of your house. There's a difference of some sort -- even if only in vividness [per Hume and Perky] -- between that imagery experience and your ordinary sensory visual experience, no?)

Of the 14 sampled experiences we discussed, Subject 1 reported 8 with visual imagery experience only and no visual sensory experience, 1 with visual sensory experience only and no visual imagery experience (the very first sample), 2 with neither sort of experience, and 3 with both visual imagery and visual sensory experience. He did not think his visual sensory experience and his visual imagery experiences interacted at all -- for example, in one sample he reported a visual sensory experience of a uniform, darkish orange field of light with a slight texture (as I understood it, he meant not a textured depth, but a bit of repetitive random variation in the color). He also had complex visual imagery of a former apartment of his. The visual imagery was not tinted orange, nor was it located in space (next to, behind, etc.) relative to the sensory visual experience.

Subject 1 generally reported his visual sensory experience with his eyes closed to be flat, two dimensional, and located in a forward direction, but without any sense of depth or distance. One experience he described as being "black with staticky [colored] swirls"; the rest he described as a lightly textured uniform darkish orange.

In coming posts, I'll describe four more subjects' reports. The big question for me: What patterns will emerge in their reports? What will they tend to agree on and disagree on? Will they all describe their sensory experience as flat? Will they all have the same view of the difference between, and non-interaction between, visual imagery and visual sensation? Will they report relatively simple, undifferentiated visual sensations, like Subject 1's? Like Subject 1, will they report visual sensory experience in only a minority of samples?

Not since the early 20th century has this sort of thing been studied systematically -- not that I have found yet, anyway! -- and early authors diverged considerably in their opinions.

2 comments:

Keith said...

Eric -- This is a fascinating, and I'll look forward to reading the rest of the reports. Your first subject is clearly a sophisticated one, and it will be interesting to see if non-philosophers make a similar distinction sensory visual experiences and visual imagery. Did you ask your subject how he came to make the distinction? Was it the result of studying philosophy, or had he always made such a distinction, on purely introspective grounds?

By the way you missed a great title for these posts: 'Eyes Wide Shut'.

Eric Schwitzgebel said...

Thanks for the encouraging remarks! I asked all my subjects to consider whether there was a distinction of this sort -- since I think there is a distinction (even if only in vivacity?) and I wanted to bear as clear as possible on what they were reporting, whether it was imagery or sensation. I tried not to twist people's arms about it. All subjects, except maybe Subject 5, explicitly accepted the distinction. It's hard to know, though, to what extent subjects entered the experiment with an antecedent commitment to the distinction.

"Eyes Wide Shut" -- of course! ;)