A familiar technique in rhetoric is to group in threes because people can hold only a few items in short-term “working” memory.
- The Olympic motto: Faster, Higher, Stronger
- Rights proclaimed by the Declaration of Independence: Life, Liberty and the Pursuit of Happiness
- Fire safety technique taught to children: Stop, Drop and Roll (should their clothes catch fire)
Three-part lists are particularly appealing because they suggest unity and wholeness. Lists comprising only two items seem inadequate. Lists of four or more are unlikely to be recalled entirely.
Idea for Impact: Follow the rule of three to create simple, concrete, and memorable messaging in persuasion—be it in arguing, storytelling, or advertising.