(a.) Inner speech. You "hear" (or more accurately auditorially imagine) a voice -- maybe your own voice, or the voice of the author, or the voice of a character, or some other voice, saying the words you are reading.I'm inclined to say, in my own case, that (a) and (c) are pretty much constant and (b) comes and goes. I also would have been inclined to think that (a) and (c) would be pretty universal for everybody and (b) highly variable between people. But it turns out that reports of (a) and (c) are also highly variable.
(b.) Visual imagery. You experience visual images of the events described or hinted at in the text, or maybe images in other modalities (auditory images besides those of the words you are reading, maybe tactile images, olfactory images, motoric images).
(c.) Sensory experience of the text. You visually experience the text on the page, that is, the black and white of ink on paper or pixels on the computer screen.
For example, the research participant "Melanie", interviewed in my 2007 book with Russ Hurlburt, says that normally when she reads she starts out in inner speech and then "takes off" into images, leaving the inner speech behind (comparable to the difference between an airplane taxiing and flying; p. 101). When she is asked to report on two particular moments of experience while reading (having been interrupted by a beeper), she comes pretty close to explicitly denying that she has any sensory experience of the text on the page (e.g., p. 100).
Julian Jaynes says to his readers "And as you read you are not conscious of the letters or even of the words or even of the syntax or the sentences and punctuation, but only of their meaning" (1976, p. 26-27) -- thus seeming to deny at least visual experience the text on the page, and probably auditory imagery or inner speech of the words as well.
In contrast, Bernard Baars seems to assume the near-universality of inner speech, writing: "Human beings talk to themselves every moment of the waking day. Most readers of this sentence are doing it now" (2003, p. 106).
Wittgenstein writes: "Certainly I read a story and don't give a hang about any system of language. I simply read, have impressions, see pictures in my mind's eye, etc. I make the story pass before me like pictures, like a cartoon story" (1967, p. 44e).
Charles Siewert writes, after quoting the Jaynes passage above: "[If] Jaynes is denying that we consciously see the book, the page, or anything printed on it, then it seems what we are asked to believe is this: typically when we read, we function with a kind of premium-grade blindsight.... I find this extreme denial of visual consciousness, once made plain, very strange, and just about as obviously false a remark as one could make about visual experience" (1998, p. 248-249).
Max Velmans, like Siewert, seems to find the visual experience of the text mandatory, inner speech more optional: "When consciously reading this sentence, for example, you become aware of the printed text on the page, accompanied, perhaps, by inner speech (phonemic imagery), and a feeling of understanding (or not)" (2002, p. 16).
Gavin and Susan Fairbairn, in a text intended to instruct college students in better reading, write: "In contrast to the experience of those who find that they are conscious of every word when they read fiction, many people find, especially but not exclusively when they are reading fiction, that when they 'get into' the text they seem to be aware of meanings, sounds and pictures, even smells and feelings, without any conscious awareness of the words used to convey them.... Hearing the sounds of words when you read can be a handicap" (2001, p. 25). This view seems rather close to Melanie's analogy to taxiing and flying.
Almost all these authors -- Melanie is of course an exception, and Wittgenstein may or may not be -- take these statements to describe the experience of reading in general, not just for themselves individually. Obviously, though, they reach very different conclusions. (Such is consciousness studies!) As far as I'm aware, however, no one has ever published a systematic study of the matter.
Quotes, descriptions of your own experience, etc., warmly welcomed in the comments section.
(Thanks to my student Alan Moore for some of the quotes above. His own interesting work on the experience of reading will hopefully be the topic of a future post.)