To the things I "see with my eyes shut" there are few limitations, the pictures are colored, real, the details are distinct.
My response is not limited to the degree with which the author describes and makes vivid. A mere hint suffices to draw a really definite picture in my mind. If the author doesn't spoil my own picture with too damned many cloying details I'm better satisfied. I dislike wading through paragraph after paragraph of detailed description, unless an accurate picture is necessary in order to give a complete understanding of certain action or certain moves made by a character.
I carry that dislike for detailed description into my own work. If I use more than one sentence of description I wince. I like to convey a picture, a real picture in as few words as possible. I like to put action into my description, into my picture of a setting.
I never have stock pictures. A village church? Immediately before my mind passes a parade of all the village churches I have ever seen, in villages or movie lots.
My dislike for description applies to characters as well as scenery. A hint here and there, characterization—things that will make each reader furnish the details he likes best. I might have described them in detail—mere words to tell how they appear in my picture. Really now, when you read about characters, doesn't your mind supply a picture of the physical man? A man to your liking, unhampered by clogging, useless words? Didn't characterization do that? If you have a leaning toward dark heroes, you conceive him to be dark. If to your mind a guy with red hair is the real Peruvian gooseberry as the main character, red headed he'll be in your mental picture. Etc., etc.
Is there any difference in behavior of your imagination when you are reading stories and when writing them? I live with my characters both in reading and writing, but oh! what a difference. In writing, I have to work out the problems; in reading, the problems have been worked out by the author. It's traveling with a sled, but one is going up-hill and the other down-grade.
Mary Johnston: Impossible to answer this fully. Sometimes there is a high degree of reality, at other times less. Depends upon the amount of energy that is functioning, energy and attention.
Yes, it is possible to see things with your eyes shut. I see them colored, in the round, and at times in motion. Not always in minute detail. Often only a general impression.
No more trouble from solid geometry.
As to response, if you have the concept, you can produce the appropriate phenomena. Individual pictures usually. Sometimes a composite or an idealization.