I have been re-reading Edward Tufte's essay "The Cognitive Style of Powerpoint". As one who has sat through seemingly endless Powerpoint presentations, much of what he says makes instant sense. This reading struck a particular chord with me-perhaps because of the boatbuilding project I'm currently working on.
One of Tufte's particular points concerns the very low information density of those sorts of images presented in that way. Text-based slides have between 10 and 20 seconds worth of reading material on them. Graphs are limited by the coarse resolution of the projection system-besides, I can't imagine staring at a projection screen long enough to make any worthwhile conclusions.
In contrast, I considered the number of pages necessary to describe a boat sufficiently to build it. In the case of Apple Pie, the instructions consist of 16 pages, including the story of her design, though only 5 are actually necessary to build the boat. This is a boat for a beginner. A design intended for a more advanced builder is the Egret. The plans consist of 4 large sheets-maybe equal to 16 pages-but the job could have been done in fewer. The amount of essential information contained in what are nothing more than line drawings is astonishing.
It is true that both in both these cases it is assumed that you know something about building things. But the same is really true in the case of any other presentation-it is assumed you have some level of pertinent background. I can't imagine a presentation which first explains how to interpret a pie chart before showing you a pie chart. That knowledge is assumed by the presentor. A set of plans have several things to their advantage. The first is that they speak a common language. Once you've learned to interpret a table of offsets for a boat hull, you've pretty much got the whole thing licked-for any other boat plan as well. With a little additional reading-maybe one or two books-you've got construction methods under control. Another advantage is that a set of plans isn't trying to convince you of anything. Tufte argues that one of Powerpoint's failings is that its communication model seems to be based on persuasion* rather than information. Everything about the product and the instructions for its use seems geared to a sale pitch rather than education.
Dale Austin 2004
All images and text Copyright Dale Austin, 1962-2008