A technique of combining many units of information into a limited number of units or chunks, so that the information is easier to process and remember.

The term chunk refers to a unit of information in short-term memory—a string of letters, a word, or a series of numbers. The technique of chunking seeks to accommodate short-term memory limits by formatting information into a small number of units. The maximum number of chunks that can be efficiently processed by short-term memory is four, plus or minus one. For example, most people can remember a list of five words for 30 seconds, but few can remember a list of ten words for 30 seconds. By breaking the list of ten words into multiple, smaller chunks (e.g., two groups of three words, and one group of four words), recall performance is essentially equivalent to the single list of five words.1

Chunking is often applied as a general technique to simplify designs. This is a potential misapplication of the principle. The limits specified by this principle deal specifically with tasks involving memory. For example, it is unnecessary and counterproductive to restrict the number of dictionary entries on a page to four or five. Reference-related tasks consist primarily of scanning for a particular item; chunking in this case would dramatically increase the scan time and effort, and yield no benefits.

Chunk information when people are required to recall and retain information, or when information is used for problem solving. Do not chunk information that is to be searched or scanned. In environments where noise or stress can interfere with concentration, consider chunking critical display information in anticipation of diminished short-term memory capacity. Use the contemporary estimate of 4 ± 1 chunks when applying this technique.2