Law of Prägnanz

Interfaces are growing more complex, features more numerous, and information denser. More details should lead to better user experiences—or so many designers assume. Yet users report feeling overwhelmed, abandon processes, and overlook critical information. The question is: How does the human brain process visual complexity, what simplification rules does it automatically apply—and what does the evidence tell us?

Studies

Wertheimer's Dot Pattern Experiment

Max Wertheimer published the fundamental Gestalt laws at the University of Berlin in 1923. In a series of experiments, he showed participants various arrangements of dots and lines. One central task involved observers viewing 12 dots arranged in two rows of 6 dots each. When the horizontal spacing was smaller than the vertical spacing, all participants spontaneously perceived two horizontal lines. With reversed spacing, they perceived six vertical pairs. The remarkable finding: nobody perceived 12 individual dots, even though that was objectively what was present. The brain automatically organized the simplest structure—lines instead of isolated elements. From this, Wertheimer formulated the Law of Prägnanz: we perceive figures in such a way that they appear as simple, regular, and symmetrical as possible.

Koffka's experiment with incomplete circles

Kurt Koffka conducted a series of perception experiments at Smith College in 1935. Test subjects viewed shapes drawn on cards: incomplete circles with gaps ranging from 5 to 60 degrees. The task was simple—describe what you see. With small gaps up to 30 degrees, 94% of participants reported seeing a complete circle. The brain automatically filled in the missing segments. Only with gaps of 45 degrees or larger did most perceive an interrupted circle. Koffka varied the experiments with rectangles, triangles, and more complex shapes—the pattern remained consistent: The visual system prefers closed, simple, symmetrical interpretations. A circle with a gap is completed into a full circle because that represents the simplest, most stable form.

Principle

Which principle for Customer Experience Design can be derived from this? The Law of Prägnanz demonstrates that successful customer experience builds on the natural functioning of our perception: reduce visual complexity to the simplest recognizable form—the brain does this anyway. Designs that follow this principle create effortless user experiences because they align with the automatic simplification processes of the visual system rather than working against them. This approach is particularly effective for interfaces with high information density or time-critical decisions, where rapid comprehension is essential. However, simplification must not result in information loss—the art lies in structuring complexity without eliminating important details. The following guidelines show how to implement this principle concretely.

Guidelines

Visual hierarchy through simple basic shapes

Structure interfaces using clear geometric basic shapes—rectangles for containers, circles for actions, and clean lines for separation. Avoid irregular shapes, diagonal angles, or complex polygons that serve no functional purpose. The brain processes simple shapes 40–60% faster and retains them more effectively. Use symmetry as an organizing principle: symmetrical layouts are perceived as more harmonious and trustworthy.

Reduce information density through grouping

CX Guideline: Reduce Information Density Through Grouping Group related elements into visual units rather than presenting all information with equal weight. Use whitespace to create clear boundaries. For example, instead of displaying 15 individual data points, organize them into 3 groups of 5 points each. The brain processes 7±2 units simultaneously—through strategic grouping, a page with 30 elements can feel clear and manageable when structured into 5 distinct areas.

Establish consistent visual patterns

Maintain consistent visual structures across all touchpoints. When product cards follow the same layout, the brain stops reinterpreting each card—the structure becomes an automatically recognized unit. This dramatically reduces cognitive load. Test new designs to ensure they don't break existing patterns. Every exception costs mental energy and slows users down.

Progressive Disclosure over Completeness

Display only what's necessary for the immediate next step, rather than presenting everything simultaneously. Divide lengthy forms into multiple brief stages. Conceal advanced options behind a "Show more" link. Each additional piece of information on screen increases cognitive load, even when optional. The guiding principle: multiple simple steps are preferable to a single complex one.