TITLE:
Probability Theory Predicts That Chunking into Groups of Three or Four Items Increases the Short-Term Memory Capacity
AUTHORS:
Motohisa Osaka
KEYWORDS:
Short-Term Memory, Chunking, Probabilistic Model, Credit Card Number
JOURNAL NAME:
Applied Mathematics,
Vol.5 No.10,
June
3,
2014
ABSTRACT: 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 ۬ 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.