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