Data visualization means different things to many people. To some it's an analytical tool while to others it's a way to make a statement. In my experience, those interested in data visualization fall into these five categories.
Technicians are all about implementation. They have a strong programming background with experience in Processing, Actionscript, or some other similar language and probably have worked with large databases at one point or another. To technicians, aesthetics is not as important as getting things to work. After everything - database, hardware, code - is hooked together, it is then the technician tries to spruce things up. Show them a visualization and they'll want to know to know how it was made.
Data is priority to analyzers. Like technicians, aesthetics are not the greatest concern; rather, analyzers want to know the relationships between variables, find positive and negative trends, and are most likely to tell you that you should have used a different type of graph or chart for that dataset. Tools like R, Microsoft Excel, and SAS are analyzers' weapon of choice. Many will have programming experience but don't code as well as technicians. Show an analyzer a visualization and they'll most likely comment on the (complex) patterns they see.
Artists are obsessed with the final product - what the visualization will finally look like. They are the designers who are most likely to think long and hard about colors, visual indicators, and whether or not that square box should be moved up 2 pixels to the left. Programming is not a strong point, but if it is, it's most likely in Processing. The weapon of choice though is the Adobe Creative Suite, namely Illustrator and Photoshop. Artists are most likely to tell you that something is ugly.
The outsider is the one with a complex data set but not quite sure what to do with it. Outsiders are the field experts who want to visualize their data but might not have the know-how to follow through. They can, however, provide plenty of context and usually have a sense for what their data is about. You'll most often see the outsider with a pen and paper explaining things to the technician, analyzer, and artist.
The Light Bulb
Light bulbs are the idea people. They've got some programming, design, and analytical experience, but they're not necessarily experts in all three areas. Because of all the experience, the brighter bulbs can usually handle a large data visualization project on their own (if they had the time). Knowing what's possible and not possible, light bulbs lead projects and can delegate work across a team. It's all about the big picture for the bulbs while the brightest are like the zen masters of data visualization.
I consider myself some combination of the analyzer and technician. I'm still searching for the artist in me. I've got some design experience, but there's still a lot to learn - always more to learn.
What data visualizer type are you?