There are a range of factors that may impact whether students read all of the comments made about their work, but I believe three factors play a big role.
1. Student view the mark as more important.
2. The feedback isn't timely.
3. Students see no opportunity to demonstrate improvement.
I'll go back in time to when I was in high school and learning how to drive. As a student driver I was offered lots of feedback on how I was progressing and what I could do to improve. Much like any teenager, I was highly motivated to learn and knew that it was important to do so in order to pass my road test. The feedback was descriptive, specific, immediate and all along remained very supportive. Not once was I graded while I was learning and in no way was the feedback provided in a way that seemed judgmental. I always knew the feedback was designed to help me improve and I also knew I had opportunities to demonstrate my improvements. Because the feedback was so immediate, I did everything I could to apply the feedback and make the necessary improvements.
Eventually, the day of my road test came up on the calendar. To the best of my ability, I followed all of the evaluator's instructions and executed what was asked of me. When I finished my road test, I anxiously awaited the decision of the evaluator. When he told me the result (and yes, I did pass!) I remember feeling ecstatic yet relieved. I know the evaluator offered a number of comments about my driving, however, as much as I am ashamed to admit it, at that moment I didn't really listen too closely to his comments. Why not? For starters, my focus on the result overshadowed all of his comments. Second, because the evaluator's comments came at the conclusion of my road test, they weren't as helpful as they could have been if he provided them throughout the test. Third, I knew that my road test was complete and I wouldn't have to, nor would I be afforded the opportunity to demonstrate improvements based on his suggestions.
Feedback should tell students what and how they can improve in their learning. It must be formative. The types of feedback offered by a teacher will differ based on the subject and learning task it pertains to. It might consist of suggestions on how to improve a draft of a written submission, point out how to correct a mathematical process, how to place one's fingers in order to play a note more clearly, etc.
And what can we do to increase the effectiveness of our feedback?
In order for students to act on our feedback, it must be timely. Feedback, being formative in nature, must be consistently provided during the process of learning so that students can incorporate the suggestions into their work and into their ongoing practice. Regardless of the type of feedback, what's crucial is that students be provided the opportunity to apply the feedback to their work. This means that a mark should not accompany feedback. Feedback must precede the mark. This tells students that the feedback is designed to help them improve their work before a judgment is made. Students should not be penalized in the gradebook for errors they make while learning. We must provide opportunities for practice without penalty!