Chunking (Miller's law)
People hold only a few chunks of information in mind at once.
Where it applies
Three of the eight page areas.
HomepageNot typical CategoryNot typical SearchNot typical ProductAlso applies CartNot typical CheckoutMainly here Post-purchaseNot typical
It also applies sitewide, on every page. See everything at work on Checkout pages
How to use it
Five ways to put it to work.
- Group form fields into short labelled sections.
- Auto-format card numbers in blocks of four (4-6-5 for American Express) and accept typed spaces.
- Show phone numbers in blocks.
- Group navigation items.
- Bullet the key specs.
What the research found
“Seven plus or minus two” is outdated. No controlled ecommerce study was found.
“Seven plus or minus two” is outdated: in young adults the limit is about four chunks.
'Seven plus or minus two' is outdated. Cowan's reviews put the limit at about four chunks (three to five) in young adults. It is not a rule for menu length. No controlled ecommerce study was found. Baymard's usability testing shows shoppers type and check card numbers in blocks of four.
Key research
Four sources, each checked.
Last reviewed
Miller (1956) The magical number seven, plus or minus two: Some limits on our capacity for processing information Psychological Review Read the source Cowan (2001) The magical number 4 in short-term memory: A reconsideration of mental storage capacity Behavioral & Brain Sciences Read the source Cowan (2010) The Magical Mystery Four: How is Working Memory Capacity Limited, and Why? Current Directions in Psychological Science Read the source Söderlund (2017)Industry The 'Credit Card Number' Field Must Allow and Auto-Format Spaces (80% Don't) Baymard Institute Read the source