Textbook of Usability

Chunking is the cognitive process of organising individual elements into larger, meaningful units. By forming chunks, users can hold more information in working memory, because each chunk counts as a single item regardless of how many elements it contains.

A classic illustration: the string "FBICIAUSANASA" is 12 unrelated letters — well beyond working memory capacity. But recognised as "FBI CIA USA NASA", it becomes 4 chunks, comfortably within capacity. The information content is identical; the cognitive load is transformed.

Chunking depends on knowledge stored in long-term memory. An expert can chunk complex patterns (a chess grandmaster sees meaningful positions where a novice sees individual pieces), while a novice must process each element individually.

Design applications:

• Phone numbers formatted as 3-3-4 digits ("021-555-1234") rather than unbroken strings
• Credit card fields split into groups of four
• Visual grouping through whitespace, borders, and headings
• Hierarchical menus that group related items under categories
• Progress wizards that break long tasks into meaningful stages

Chunking is the primary mechanism for working around Miller's and Cowan's capacity limits. The total amount of information doesn't change — the number of independent units the user must juggle does.