garage sale signs and data viz: the power of preattentive attributes

I was jogging the other morning and ran by a woman hanging a sign for a garage sale. Her advertisement was penned on a piece of yellow 8x11 paper, uniformly golfball-sized letters describing the detail. In short: someone would pretty much have to stop their car, get out and walk up to the sign to know what it said. And after doing so, would need to read the entire sign to find out the most relevant parts of the detail: if it was in an area of interest, or at a time that would suit.

This was obviously a poor sign. The only thing it had going for it was that the yellow paper was eye catching. But I imagine that only those in search of garage sales would think of stopping to pay it more attention; the sign was clearly not going to be read by the majority of passersby.

This led me down a thought path: what makes a good garage sale sign? I had a hypothesis. After arriving home, I looked up images of garage sale signs with my favorite search engine. Here's a sample:

It seems to me that one of the things that makes for a good garage sale sign is one of the same things that makes for a good data visualization: strategic use of preattentive attributes.

"Preattentive attributes" in the world of information visualization is a fancy descriptor for aspects of a visual that hit our iconic memory. Iconic memory is what happens in our brain before short term memory kicks in, before we even really know that we're thinking. Iconic memory is tuned to pick up preattentive attributes: things like color, size, added marks, and spacial position [learn more].

In the lessons I teach on data visualization, I discuss using preattentive attributes mainly with two goals in mind: 1) directing the audience's eye and 2) establishing a visual hierarchy of information. In both cases, the point is that if you use preattentive attributes well (especially color), your audience can't help but focus on the important part(s) of the message. By playing on their iconic memory, you're making it so they are seeing what you want them to see before they even know they are seeing it. Which is a crazy powerful thing.

I have a good Google before-and-after example that's been genericized that I'll post later this week. If you're too excited to wait, I'll be discussing it (and more on preattentive attributes) at the meet up on Thursday in Mountain View [see details].