Textbook of Usability

The Von Restorff effect (also called the isolation effect) is the memory phenomenon in which an item that stands out from its surroundings is more likely to be remembered than items that blend in. The effect was described by German psychiatrist Hedwig von Restorff in 1933.

In Von Restorff's experiments, participants shown a list of similar items (all numbers, say) with one distinctive item embedded (a word) remembered the distinctive item far better than the surrounding numbers. The effect holds across many kinds of distinctiveness — colour, shape, size, semantic category.

Design applications:

• Call-to-action buttons that differ from surrounding elements in colour or style receive more clicks
• Pricing tables highlight the "recommended" plan with a distinct colour or size
• Primary actions should stand out from secondary actions
• Error states should differ clearly from normal states
• Success messages should be visually distinct from default content
• Feature highlights in changelogs or tours use isolation to mark new functionality

The effect is related to pre-attentive processing (Chapter 2) but operates at the memory level, not just the perception level. Distinctive items are not only seen first; they are remembered later.

The Von Restorff effect can be used ethically (to draw attention to safe defaults or important choices) or manipulatively (dark patterns that use distinctiveness to draw users toward profitable options they wouldn't otherwise choose).