Critical Thinking Regarding Color

In Launching the Imagination, Stewart says that critical thinking regarding form, including color choice, can enhance a design and strengthen communication. I was reminded of this while reading an article about the work of a cartographer, Cindy Brewer, who created a website to help map makers improve the readability of their maps through color schemes that are a good fit for the data. Some of the guidelines she provides regarding different types of data:

• Sequential data (values go from low to high, like population density or temperature): Color scheme that progresses from light to dark. Never use rainbow colors for this!
• Deviation from an average: A diverging color scheme, with for example reds at one end and blues at the other
• Different categories (like religions or ethnicities): Up to 12 colors that are easily distinguishable, fewer is better. After about 7, it can get really hard to tell them apart