Memory & Attention
Miller's Law
The average person can hold only about 7 (±2) items in working memory at once.
Mechanism
Why it happens
Working memory has a small, fixed capacity; chunking related items into groups lets people reason about far more of them at once.
Impact
Why it matters
- Long, ungrouped lists and forms exceed working memory before they're finished
- Chunking is free. The information doesn't change, only how it's grouped
- Overloaded working memory shows up as errors, not just slower completion
Example
Without vs. with
Without
A single 24-field signup form runs top to bottom with no section breaks.
With
Contact
Address
The same 24 fields split into four 6-field steps with a visible progress indicator.
Checklist
How to apply it
Group form fields into chunks of five to seven with clear section headings
Limit top-level navigation to around seven items; nest the rest
Chunk long numbers and codes visually (555-0102, not 5550102)
Carry state forward between screens instead of relying on people to remember it
Where it shows up
Element areas
FormsNavigationTables