[quoting Perry, 22 Oct 96] I currently work in an organization that comes from the world of video. For years now, I have been concerned that our use of narration is not as affective as the use of text. My conviction is that students reading text to receive a message is a more active process than narration, which is a more passive mode. For now, I go on what I deem is common sense.
Since students learn in a mixed-media environment, the "either/or" discussion seems somewhat limiting. I have been more fascinated by research that focuses on how to effectively combine media so that we draw on the strengths that each medium has to offer. I'm thinking, for example, of Bruce Mann's work on the positive effect of combining sound with text (1995). I don't particularly care which one is better. What interests me is that together they are stronger than either one alone. From a practitioner's standpoint, that's news I can use!
Mann, B. (1995). Focusing Attention with Temporal Sound. Journal of Research on Computing in Education, 27(4), 402--424.