I always knew my credit card number is grouping as 4 digits per group but never thought about why. Today I had an interesting reading about short-term memory. Research has been done showing that short-term memory capacity is a function of chunks rather than the objective number of items. That being said, if you try to remember a string of numbers or digits, divide them into small groups could improve the recall performance. Specifically, Wickelgren (1964) showed that a string of digits are easiest to remember if they are divided into groups of a maximum of four. That’s one of the underlying reasons why we have credit card numbers being organized in groups. Though each part does present different information, but its presentation in groups is also an important strategy to make it easier for customers to check and remember. Similarly, when we design the presentation of information, make sure not offering too much at a time. Instead, group them to make it simple for users to recall.
Wickelgren, W.A. 1964. Size of rehearsal group in short-term memory. Journal of Experimental Psychology, 68, 413-419.