Probability Theory Predicts That Chunking into Groups of Three or Four Items Increases the Short-Term Memory Capacity

DOI: 10.4236/am.2014.510140   PDF   HTML   XML   3,053 Downloads   4,242 Views   Citations


Short-term memory allows individuals to recall stimuli, such as numbers or words, for several seconds to several minutes without rehearsal. Although the capacity of short-term memory is considered to be 7 ± 2 items, this can be increased through a process called chunking. For example, in Japan, 11-digit cellular phone numbers and 10-digit toll free numbers are chunked into three groups of three or four digits: 090-XXXX-XXXX and 0120-XXX-XXX, respectively. We use probability theory to predict that the most effective chunking involves groups of three or four items, such as in phone numbers. However, a 16-digit credit card number exceeds the capacity of short-term memory, even when chunked into groups of four digits, such as XXXX-XXXX-XXXX-XXXX. Based on these data, 16-digit credit card numbers should be sufficient for security purposes.

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Osaka, M. (2014) Probability Theory Predicts That Chunking into Groups of Three or Four Items Increases the Short-Term Memory Capacity. Applied Mathematics, 5, 1474-1484. doi: 10.4236/am.2014.510140.

Conflicts of Interest

The authors declare no conflicts of interest.


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