Miller’s Law states that the average person can only keep 5–11 items in their working memory at a time. The working memory required to complete a task within your product is proportional to the mental interaction cost, the burden you impose on your users.
At no point should your task require the user to hold more than seven items in their working memory at any moment.
Use “chunking” to reduce their mental burden
In scenarios where we require the user to hold more than 11 items in their memory, we should use “chunking” to reduce their mental burden.
Chunking is when individual pieces of an information set are broken down and then grouped in a meaningful whole. For example, we remember phone numbers as XXX-XXX-XXX rather than XXXXXXXXX. It’s easier to remember the number in 3 chunks rather than 9 individual units.