Oh dear. I've just returned from a week underwater in the Philippines to find my mail box full of arguments about grocery trucks. I'm the person who made the unfortunate remark back in July that I thought we'd put this argument to rest--the ensuing cat fight kept us amused and occupied (though not necessarily enlightened) over the Summer. [see: An ITForum Discussion of Interactivity and Grocery Trucks]
Obviously my brain is still too waterlogged to comprehend how we got back into the realms of putting rats through mazes, but I'd like to make two very short observations on Steve's experiment (and Jeff's [Oliver, 21 Oct 96] nightmare extrapolation).
(1) Richard Clark did not conduct any experiments to prove that media do not influence learning. He was one of many (Chu, Schramm, Levie & Dickie, Lumsdaine, etc.) who conducted meta-analyses of the previous 40 years of media-learning research and showed that almost all of it was based on the model of scientific objectivism (i.e., the idea that one can hold conditions constant, change one variable to observe the result, and the (totally unsupportable) view that the "results" of such an enterprise can be generalized). Even in "straight science" this view is no longer generally accepted--viz. the theory of quantum mechanics. I believe that the most important contribution made by Clark is to establish that quantitative methods of research will never establish if/how media influence learning. Clark's greatest crime was to coin a very provocative metaphor.
(2) Previous discussions had given me the impression that constructivism was the flavor of the month. Now, unless you are a Zen master (maybe Steve is!) you can't hold two totally opposing views at the same time (i.e., the Constructivist view that learners create their own knowledge AND the old Instructivist model of educational technology). Different learners will enjoy and profit by different means of accessing, constructing and using information. Choice is useful. Media (as any teacher of art, creative writing or Logo will tell you) are great vehicles for student to learn with.
Embrace complexity. (Was it Tom Reeves or Bob Dylan who said that?)