In your experience with teachers who respond to your writings, you may have walked away from the situation feeling more bruised than enlightened. Peter Elbow contends that writers don't need (even though they may contend otherwise) and generally don't make much use of advice about how to write. But writers do want readers to react and respond in some way, even if it is a way that is unexpected, to their writing. Elbow argues that what writers most want to know is "what happened when you read this writing?" and that it is the answer to this question that can be put to best use by writers. What a writer wants and needs, says Elbow, is a reader's "movie of the mind." [See Peter Elbow, Writing Without Teachers 77-78, 85-92 (New York: Oxford University Press, 2nd ed., 1998)] When you provide another writer with a "movie of the mind" you are simply relating to them your experience as a reader. Remember, you are not trying to tell the writer what to do but what happened to you during the course of your reading.
Peter Elbow contends that "[t]o improve your writing you don't need advice about what changes to make; you don't need theories of what is good and bad writing. You need movies of people's minds while they read your words."  A movie of the mind is a subjective but factual statement of what happens when you read. It is an effort to give reactions and not just conclusions.  Don't worry, says Elbow, about whether anyone else will agree with you, or whether the author will be pleased, puzzled, or disturbed by your reaction. As authors we must surely want to write well, but we also want to affect the reader, to evoke a response. It is impossible to know how your writing works unless your reader is willing to respond. Remember that even "the perceptions of a hostile reader are useful." 
Elbow outlines four ways to present a "movie of the mind" when you respond to a writing: (1) pointing, (2) summarizing, (3) telling, (4) showing.
Pointing. "Start by simply pointing to the words and phrases which most successfully penetrated your skull: perhaps they seemed loud or full of voice; or they seemed to have a lot of energy; or they somehow rang true; or they carried special conviction. Any kind of getting through. . . ." [85-86]
"Point also to any words or phrases which strike you as particularly weak or empty. Somehow they ring false, hollow, plastic. They bounced ineffectually off your skull." 
When you read, mark the words and phrases that get through to you, and mark the ones that are weak, empty, hollow, or false.
Summarizing. The next step is to summarize the work. One way to do this is to complete the reading and then ask what remains with you? Summarize it in a single sentence. "The point is to show the writer what things he [or she] made stand out most in your head, what shape the thing takes in your consciousness. This isn't a test to see whether you got the words right. It's a test to see whether the words got you right. Be sure to use different language from the language of the writing. This insures that he [or she] is getting it filtered through your perception and experienceónot just parroted." [86-87]
Telling. In telling you "simply tell the writer everything that happened to you as you tried to read his words carefully. It's usually easiest to tell it in the form of a story: first this happened, then this happened, then this happened, and so on." 
Showing. The final way to present a movie of your mind for reading requires that you talk about elements of your experience in the reading for which you do not have an easily summarized view. When we read we have perceptions and reactions, sometimes faint ones and are not fully conscious. Consequently, we must try to capture these responses by showing rather than telling. Here are some ways that Elbow recommends for showing:
Elbow points out that doing these exercises may seem strange and uncomfortable at first and that you should not expect to be very good at this kind of response until you overcome the reservations you might have about doing them. 
In Writing With Power, Elbow provides still more guidance on how to provide feedback to another writer. [237-239] Elbow distinguishes criterion-based feedback and reader-based feedback. (240-251). Criteria-based feedback proceeds, in Elbow's view, from the following questions:
Criterion-based feedback deals with the "quality" of writing.  This is the kind of feedback that we are most accustomed to getting from teachers.  It attempts to diagnosis the strengths and weaknesses of your writing. 
Reader-based feedback, in contrast to the quality-oriented criterion-based feedback is what Elbow calls "movies of a reader's mind"  This feedback "tells you what it [your writing] does to readers."  Reader-based feedback responds to the following inquiries:
Elbow goes on to offer still more specific reader-based feedback questions:
While both kinds of feedback can be useful, Elbow favors reader-based feedback. "Reader-based feedback gives you the main thing you need to improve your writing: the experience of what it felt like for readers as they were reading your words." 
Note: Professor Gerald Grow's wonderful drawing cartoon, is used with his permission. His other interesting work can be found at: Professor Grow's Home Page.