Visuale

I found really fascinating this eyetracking heatmap form one of the latest Jakob Nielsen's Alertbox articles.

The areas where users looked the most are colored red; the yellow areas indicate fewer views, followed by the least-viewed blue areas. Gray areas didn't attract any fixations.

As argued by Nielsen, the dominant reading behavior follows an F shape: a first horizontal movement, a second horizontal movement a bit below, and a vertical scan on the left, and it is quite consistent over several different types of web pages and tasks.

It's incredibly fascinating to see how visualization can help in tracking and then displaying human behaviors in a way that makes emergent patterns readily visible. There is a growing interest and focus on collecting bits of human information and given them a visual counterpart ready for analysis. Other examples have been posted in this blog before.

The key factor of this kind of visualizations is the fact that visualization permits to see the evolution of things summed up in aggregate visual information. Frequency is often the key parameter that is used to visualize behavior: frequency of road paths, visual glimpses, airplane trajectories, etc. Alternatively, the visualization can be used to replay things at a different rate and thus to expose dynamic behaviors that couldn't be detected at a human pace.

It's a notable fact that replaying things at a different rate permits to see some patterns that would not be apparent otherwise. The image that comes into my mind is the typical video of a flower's entire life replayed in a few minutes (see this wonderful Amaryllis). Or a sequence of pictures taken always from the same position over an extended period of time. A more elaborated idea is Alan's Slow Time: if we could replay our life and use band-pass filters to select things that routinely happen at very low frequencies (e.g., every day, month, year) we could notice interesting recurring patterns of ourselves. Notably, finding your keys!:

Take the home. Band pass in the millihertz range. Start off by removing the things faster than millihertz - to and from movements of people disappear and we are left with the things that change only slowly - rather like a series of long exposure night-time frames, the hurrying people become ghostly mist against the background. Now remove the things that do not change in the millihertz range, things that are the same for hours and days. Watch the resulting images, just the moments of millihertz change - the things put down and picked up, or perhaps put down and never picked up - "that's where I left my keys!"

It would be great to see one day this idea realized in a real prototype.

I find it quite bizarre that the name information visualization does not contain any explicit reference to interaction. And that is true even if its traditional definition (and others) mention it clearly:

"the use of computer-supported, interactive, visual representations of abstract data to amplify cognition" (Card, Mackinlay, & Shneiderman, 1999)

After all, there should be a difference between paper-based static visualization (i.e., Tufte's like) and interactive visualization, isn't it? There should be some added value when interaction is taken into account.

Maybe the name would be too long or complex with additional words? Or maybe who invented the name (my guess is Stuart Card) implicitly intended to include interaction in the name as it is? I don't know. However, I think it is a matter of fact that information visualization is often perceived only as the science of finding the best visual representation for depicting data, completely neglecting the primary role interaction should have.

I don't want to seem a purist, but personally I think we should be aware of this fact when speaking of visualization and, more importantly, when we teach about it. In my experience, students and newcomers, get stick with the idea of representation and completely forget the other half of the story.

These can be some of the causes:

• The name. As I said before, the name information visualization suggests the idea that it is only about visualization that we talk about and not interaction. Notably, the information visualization research page at PARC (where infovis was, partially, invented) is now called "Information Visualization & Interaction".

• Visualization is "visible", interaction is not. When showing visualizations to people, what really stands out at first is the visual part not the interactive. Colors, shapes, regular patterns, remain impressed into one's mind and create a pleasurable experience that strongly influences the perception of it.

• Heritage from visualization gurus. Who wants to learn how to visualize data is often (and for a good reason!) pointed to classics like Tufte's "The Visual Display of Quantitative Data" or Cleveland's "The Elements of Graphing Data". Unfortunately, however, these old gurus teach you very well how to transform data in visual structures but not how to interact with them. Moreover, the good books that teach you also the interactive side (e.g., Readings in Information Visualization) seems to be a lot less structured and organized in its description than for the visual part.

• Interactivity is hard to program and thus to practice. As demonstrated by the plethora of web visualizations with few interactive capabilities, it is relatively easy to program few lines of java code to transform data into a visualization. Much more harder (and time consuming) is to program interaction; dealing with selections, filtering, coordinated views, etc. The result is that there are much more static digital visualizations than interactive ones.

• Interaction is hard to teach. Visual mappings can easily be shown through images in books and slides in class, and be profoundly criticized through inspection. Interaction requires dynamics and real demonstrations. Ideally, students should directly "do" the things to learn and criticize and this is not always feasible/possible. Second, the body of literature around interaction for visualization is much more dispersed and not very well developed. While it is quite easy, for instance, to find taxonomies, empirical studies and classifications, of visual techniques, the same does not hold for interactive techniques.
  

It is true that visualization on paper can also help in reasoning and exploration, to some extent, but its main purpose is to communicate and elucidate something that has already been elaborated and digested by a designer. It is only with interaction that one can really reason about a data domain, explore it under different points of view, and manipulate the medium to accommodate new questions coming to mind.

There are various reasons why interaction is really fundamental and a big leap forward with respect to static representations. As I was saying, data exploration is useful to find new questions more than clear answers (notice that this last feature seems to be at the same time the strength and weakness of information visualization), therefore interaction is really fundamental because as soon as new questions pop up, new views an mappings are necessary. Also, when the information to put on the screen is too much, as often happens, it is necessary to select what must always be visible on the screen and what extra-information can only be accessed by means of mouse clicks. Without interaction the designer is forced to put all or nothing.

It's strange the fate of interaction. The measure of its success is the extent to which it gets unnoticed, that is, how naturally users can manipulate things without too much cognitive effort. However if it is successful, it get unnoticed, and thus nobody remembers it.

I'm eager to come back to these points. I feel there is much more to say about it. What do you think? Is it important or not to deal with this type of questions (after all it is just a name!). Am I missing some important aspects of it?