A preattentive attribute is a visual property the brain notices first when it encounters a chart. Color, form, spatial position, and movement help turn a uniform wall of numbers into information a viewer can begin to decode without hunting through every value. section 2.0 section 2.1
The practical idea is simple: make the important pattern visually unlike its surroundings. A distinct color can pull attention to important values or separate qualitative categories. Form—especially length or size—can represent quantity. Position can show geography or encode a metric, as in a scatter plot. section 2.3
Choose an attribute according to the job the chart needs to do:
- Use color to highlight important values among otherwise similar marks, or to distinguish categories. section 2.3
- Use form, including length and size, when quantitative differences should be easy to see. section 2.3
- Use spatial position for geographic location or a numerical metric in a scatter plot. section 2.3
- Use movement sparingly: it can seize attention, but that same force can work against careful analysis. section 2.1.4 section 2.3
Motion that grabs the eye
A racing bar chart is a deliberately attention-grabbing use of movement, though it is not especially well suited to analysis. Gapminder’s animated World Health Chart offers a more narrative use: bubbles shift over time as income, life expectancy, population, and region are shown together, making broad rises, falls, and disruptions visually compelling. section 2.1.4
Preattentive attributes are helpers, not decoration dispensers. Use them alongside gestalt principles to present a chart’s main point clearly, then reinforce that point with a direct title, labels, annotations, or callouts. Keep visual pizzazz only when it supports the message rather than distracting from it. section 6.1.5 section 6.4
