Gestalt principles

The Gestalt principles describe how perception organises separate elements into groups automatically, before conscious thought. They come from German psychology in the 1920s, principally Max Wertheimer, Wolfgang Köhler and Kurt Koffka. Gestalt means shape or form.

The principles most used in interface design:

• Proximity: things close together are read as related. This is the strongest of them.
• Similarity: things sharing colour, size or shape are read as a set.
• Common region: things inside a shared boundary are read as a group, which is what a card does.
• Continuity: the eye follows lines and alignment.
• Closure: incomplete shapes are perceived as complete.
• Common fate: things moving together are perceived as one group.

Why proximity matters most

Spacing groups content more strongly than borders do, which is why the most common form layout error is putting a label equidistant between two fields. The user’s eye assigns it to whichever is closer, and if that is the wrong one, the form produces errors no amount of copy will fix.

Reducing the space between a label and its own field, and increasing it between field groups, fixes more than a redesign usually does.

In practice

These are the reason a well-spaced interface with no borders can be perfectly clear, and a heavily bordered one can still be confusing. Space is a grouping instrument, not leftover room.