Wednesday, February 02, 2005

Corrupting Evidence

Edward Tufte is writing a book called Beautiful Evidence, about the proper and improper use of modern rhetorical media, such as PowerPoint.

A draft chapter on Corrupt Techniques is currently available online, in which he discusses several modes of presenting misleading or corrupt evidence.

Effects without causes
Beware of presenters using the passive voice or bullet lists.
Cherry-picking
Presenters pick and choose, select and reveal only the evidence that advances their favored point of view.
Punning
Puns enable over-reaching, as sharply focused ideas tend to sprawl, grow mushy and collapse into vague metaphors when applied to content outside their original domain.
Chartjunk
Chartjunk develops from the premise that audience can be charmed, manipulated or fooled by means of content-free misdirection: garish colors, generic decoration, phoney dimensionality, corny clip-art.

There is nothing wrong with trying to persuade people - within a framework of trust and mutual respect. Corrupt persuasion is an abuse of trust.

Corrupt persuasion also carries a metacommunication, for those able to pick it up. Tufte writes: "For consumers of presentations, gratuitous and cartoonish decoration of statistical graphics has the redeeming virtue of providing insight into the presenter's integrity and analytical skills: no integrity, no analytical skills." In other words, it ain't what you say, it's the way that you say it.

Update (August 2005): See also review by Graham Shevlin of Tufte's essay The Cognitive Style of PowerPoint.

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