Tufte's Seminar of Data Display, PowerPoint and Cognition

I saw Edwards Tufte’s seminar yesterday. I am not going to summarize his more well known ideas since his seminars have been well documented elsewhere. You can find one here and another here. Tufte’s work and thoughts on information display and Powerpoint are excellent, and I’m glad that I went. I’m going to add a few general comments that are perhaps different from the hundreds of seminar summaries published elsewhere, and I'll also talk about some areas where I disagree with Tufte.

Tufte’s Style

Firstly, Tufte practices what he preaches...partly. For most of the presentation, the projector was off and he only used it to show full-sized images or videos. Other than that, it was just him talking and no PowerPoint Phluff.  Not even the usual title slide when you walk in. I suppose we already know the speaker and topic, so a title slide would have been superfluous—makes me think about which presentations of mine don’t need a title slide.

Strangely, Tufte offered little evidence to support many of the design claims that he was making. His theories and ideas seemed sound, but there was no data presented that gave scientific weight to his advice on proper data design. In his seminar, he advocates that you view a presenter skeptically, making sure that they are a "detective" without bias rather than an "advocate" of their ideas. Tufte certainly sounds like an advocate in much of what he preaches.

Ancient Texts

Tufte brought several first edition books that were hundreds of years old to demonstrate data layout by the world’s geniuses. He talks about these examples in his books, but it’s amazing to see original books by Newton and Galileo in person. I felt sorry for the person wearing archival gloves who had to slowly and delicately carry the books around, pausing at each row so the audience could see the book up close.

 PowerPoint

Accommodation of presentation design to cognitive styles is a theme of Tufte’s, which I found interesting given the current discussion of this in the blogsphere and in my own blog. Tufte argues that eliminating bullet points from presentations accommodates a diversity of cognitive styles. While it’s true that many people expect to see bulletpoint summaries of what the speaker is saying, and a few probably assimilate information best in that style, the bullet point mode is not optimal for the cognitive styles of most people. By avoiding bullet points, more people in the audience are better served. 

The PowerPoint structure entices people to reduce their syntactic discipline and causal structure in our thoughts and arguments, so in a way it affects the cognitive process of the presenter as well as the audience. Tufte’s The Cognitive Style of PowerPoint should be read for detailed thought on this topic. My final thought on this is that there must be a way to effectively use PowerPoint that eliminates Tufte’s complaints, but Tufte doesn’t offer such a solution--he recommends that a Word report be distributed at a meeting instead. To that end, Cliff Atkinson is being more realistic in his work and advice on trying to work within the PowerPoint paradigm, and Garr Reynolds at PresentationZen gives practical advice on improving PowerPoint presentations consistent with Tufte's theories.

Sparklines

Tufte spent considerable time talking about sparklines, his concept for tiny graphics inline with text that will be a significant part of his next book to be published, Beautiful Evidence. You can find some discussion of sparrklines at Agile Testing and Anil Dash.

While the concept is innovative, Tufte over-values the amount of information that these can provide. As an example, he considers the plotting of a mutual funds price embedded inline with text (the chart is the height of an uppercase letter and the length around five letters). He argues that this tiny chart consists of over 250 data points with a resolution of at least two significant digits (or, say, over 7 bits of resolution). Therefore, there are 1750 bits of information in the space taken up by four letters. This seems like a reach, since certainly the reader isn’t assimilating that many bits of information. People do a considerable amount of data reduction in their perceptual space, and the amount of bits of information obtained from such a small graph is considerably smaller than the actual resolution of the graph (think of principal components).

The fact that people can discriminate two charts/sparklines that differ in one data point doesn’t mean that they will interpret the two charts any differently—the information to the reader is the same in both. This is the classic difference between discrimination and identification: two images might be discriminable but not differently identified. In my field of hearing, a one-second vowel sampled at 44.1 khHz with 16 bit resolution doesn’t mean that there is over 705,000 bits of information in that one-second sound sample. A vowel with a formants at 710 Hz and 1100 Hz will be identified as an /a/, as will a vowel with formants at 850 Hz and 1300 Hz even though the two data points are considerable different. The two vowels can be discriminated but are not differentially identified. I believe that the analytical value of sparklines is not nearly as large as Tufte calculates.

 Tufte the Artist

Tufte spent a small amount of time showing us pictures of giant sculptures in his garden. While interesting, I’m not sure what the point of this was.

Comments

[S. Stock]

Quote: "His theories and ideas seemed sound, but there was no data presented that gave scientific weight to his advice on proper data design."

Did you not notice the 3 books and two booklets--laced with references--that were given to you as part of the class? When I attended Tufte's class, he had us open the books to the pages relevant to the point he was making. The evidence was righti n front of you.

[bwedwards]

I did, of course, receive the books and followed along with the examples. And that is what they were, examples of the theory that he was promoting. Nowhere did I see data from a hypothesis-driven study. As I mentioned, Cliff Atkinson at least cites published cognitive research data supporting his theories.

I haven't read all three books yet so perhaps such data is in there. Also, I believe that data would probably support Tufte's claims and ideas. But flipping through his book looking at beautiful reproductions of a first-edition book by Newton isn't supportive data.

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