People perceive structures in the simplest way possible.
Wertheimer's 1923 principle, and the umbrella under which the other Gestalt laws sit. Simplest means requiring the fewest perceptual assumptions, not fewest elements.
In practice
- A dashed rectangle, a partial circle and an implied triangle are all read as complete because that is the simplest available reading.
- An ambiguous org chart is interpreted as the simplest hierarchy consistent with it, which is usually wrong.