Short-term memory
Capacity
In an early and highly influential article, The Magical Number Seven, Plus or Minus Two, psychologist George Miller suggested that human short-term memory has a forward memory span of approximately seven items plus or minus two and that that was well known at the time (it seems to go back to the 19th-century researcher Wundt). More recent research has shown that this "magical number seven" is roughly accurate for college students recalling lists of digits, but memory span varies widely with populations tested and with material used. For example, the ability to recall words in order depends on a number of characteristics of these words: fewer words can be recalled when the words have longer spoken duration; this is known as the word-length effect, or when their speech sounds are similar to each other; this is called the phonological similarity effect. More words can be recalled when the words are highly familiar or occur frequently in the language. Recall performance is also better when all of the words in a list are taken from a single semantic category (such as games) than when the words are taken from different categories. A more up-to-date estimate of short-term memory capacity is about four pieces or "chunks" of information. However other prominent theories of short-term memory capacity argue against measuring capacity in terms of a fixed number of elements.
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