Laws of Perception · gestalt
Law of Similarity
Playable Play this law (~3 min)or keep reading below ↓
Elements that look alike — same color, shape, or size — are perceived as related and interchangeable, no matter where they sit. Make all links look like links and all buttons look like buttons, and users learn your interface once instead of screen by screen.
Where it comes from
Max Wertheimer published the Gestalt grouping principles in 1923 in Berlin, after noticing that flashing lights at a railway crossing were seen as one moving light rather than separate bulbs. His demonstrations showed the eye sorts a field of marks into groups by resemblance before conscious thought gets a say — rows of similar dots snap into columns or rows on their own. Uniforms, team jerseys and coin denominations run on the same instinct.
Origin: Wertheimer's 1923 Gestalt grouping papers
In the wild
- Text links
Every underlined blue phrase on a page reads as "clickable" because the first one did — one style teaches the whole site.
- E-commerce grids
Same-size product tiles signal "these are all options of the same kind"; the one styled differently reads as an ad.
- Data dashboards
Repeating one chip style for all filters lets users spot every filter instantly across unfamiliar screens.
Further reading
Don't just read it — feel it.
Play the 3-minute game and let your own reactions prove the law.
Play the lesson