In the Skinnerian tradition, reinforcement, or feedback, must follow the instructional response as immediately as possible. Other research found that delaying feedback produces better performance. It seems that when feedback is delayed initial errors are not remembered as well, thus the likelihood of using the correct response increases because the errors do not then interfere. There is no question that feedback increases lesson performance, provided that students process the instruction before seeing the feedback. Feedback acts as a unit of information, having its greatest effect when it follows incorrect responses.
Research indicates that both the content and the timing of the feedback are important.
The literature suggests that feedback is more effective when it restates the correct answer, rather than just verifying that the learner's initial response is right vs. wrong.