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Gestalt: proximity 0:33
A 33-second explainer of Gestalt: proximity, narrated over the same demo you can try yourself.
Try the interactive Gestalt: proximity demo
What this video covers
Things close together are seen as a group; things spaced apart are seen as separate. Proximity is one of the strongest cues for grouping - it usually overrides shape or colour, though a shared boundary or visible connection can override it.
You didn't decide the dots formed rows - the spacing decided it for you. Move a label nearer its field and the pairing just happens; strand it between two and the form turns into a guessing game.