Four is the score

Scientia Professor Gordon Parker

“The question here is not why Miller’s widely acclaimed paper was so explicitly imprecise (as captured so beautifully in its title), but why was four (as against seven ) not immediately in the (um) ‘fore’ front? Perhaps, his readers’ seventh sense persuaded them from closer examination?”

By Keryn Curtis with contributions

UNSW professor of psychiatry and founder of the Black Dog Institute, Gordon Parker, has poured cold water on the long held view that seven is the ‘magic number’ of items of information that the human brain can cope with before confusion sets in.

Writing in the journal Acta Psychiatrica Scandinavica, Scientia Professor Parker says a closer look at the evidence shows the human mind copes with a maximum of four ‘chunks’ of information, not seven.

His paper is a direct challenge to the highly influential paper published in 1956 by US psychologist, George Miller, which argued that the mind could cope with a maximum of seven chunks of information.

That paper, “The Magical Number Seven, Plus or Minus Two. Some Limits on Our Capacity for Processing Information”, published in the influential journal Psychological Review, has since become one of the most highly cited psychology articles and has been judged by the Psychological Review as its most influential paper of all time.

But Professor Parker says a re-analysis of the experiments used by Miller shows he missed the correct number by a wide mark.

“So to remember a seven numeral phone number, say 6458937, we need to break it into four chunks: 64. 58. 93. 7.  Basically four is the limit to our perception.

“That’s a big difference for a paper that is one of the most highly referenced psychology articles ever – nearly a 100 per cent discrepancy,” he suggests.

Professor Parker says the success of the original paper lies “more in its multilayered title and Miller’s evocative use of the word ‘magic’,” than in the science.

In the cleverly argued and frequently amusing discussion paper, Prof Parker enjoys his thorough debunking of Miller’s ‘quasi-mystical’ invocations concerning the number seven, saying  “Miller’s injunction worked like a charm and pushed seven into the foreground of our unconsciousness – compromising our usual scientific filters.”

Professor Parker says, 50 years after Miller, there is still uncertainty about the nature of the brain’s storage capacity limits.  Referencing a 2001 paper by Professor Nelson Cowan, Parker says, “Cowan speculated there may be no limit in storage capacity per se but only a limit to the duration in which items can remain active in short-term memory without rehearsal and the extent to which rehearsal itself contributes.”

“Importantly, Cowan overviewed  subsequent information indicating that there is a relatively constant limit in the number of items that can be stored in a wide variety of tasks; but with the revisited finite estimate being a ‘‘new magic number’’ of four, plus or minus one.

“The question here is not why Miller’s widely acclaimed paper was so explicitly imprecise (as captured so beautifully in its title), but why was four (as against seven ) not immediately in the (um) ‘fore’ front? Perhaps, his readers’ seventh sense persuaded them from closer examination?”

“Regardless,” says Prof Parker, “the consensus now is that humans can best store only four chunks in short-term memory tasks.”