The Birds of a Feather Rule is another good rule for how to organize information when you want to show things in groups. "We think of things in groups when they look similar or in proximity to each other," Kosslyn pointed out. Translation into PowerPoint? If you want to indicate to your audience that five things belong in a group, make them similar by giving them the same color or shape. Or group them very close together. This sounds basic, but it often means taking your data apart and reorganizing it. Kosslyn's co-panelist, Stanford psychologist
Barbara Tversky, explained that one of the fundamental principles of data visualization is, ironically, misrepresentation in order to get at the truth.