While I'm mostly interested in more complex interactive visualization tools, you can't really talk about a literacy for them without considering our literacy for simple, static charts and graphs. I recently came across a (kind of old) post about these graphics on Mike Dickison's Pictures of Numbers blog ("Deceptive Areas," "False Advertising"). They appeared in the New York Times Magazine a few months ago. As Dickison points out in his analysis, the number of inconsistencies and flat-out errors in these charts is almost comical (my personal favorite is in "The Ad Buyers" graph, where the line for item 2 starts above the line for item 3, despite that its value, 3.1, is less than the value of item 3, 3.8). These are the sorts of mistakes Edward Tufte was talking about 30 years ago, and yet we're still seeing them in the 2K7!
Obviously I don't want to make generalizations from a couple of bad examples (although I'm sure these aren't isolated incidents), but what does this mean? Clearly the designers themselves aren't paying attention to issues involved in the graphical presentation of information. The editors (of an ostensibly respectable publication) aren't catching these issues. Finally, the repeat offenses suggest that readers aren't complaining either. This seems like a pretty dismal situation.
I've read that those types of graphics started being added to stories to draw in readers who otherwise wouldn't be bothered to read the article. Does this mean that we generally don't pay attention to info-graphics anymore either? That we see a chart or graph and just skip it? Or that we are satisfied with a pretty design? What are the implications of these sorts of situations to our visual literacy?
This is something I would like to come back to again sometime.