Vol.. 63, No. 2 MARCH, 1956 THE PSYCHOLOGICAL REVIEW THE MAGICAL NUMBER SEVEN, PLUS OR MINUS TWO: SOME LIMITS ON OUR CAPACITY FOR PROCESSING INFORMATION' GEORGE A. MILLER Harvard University My problem is that I have been perse- cuted by an integer. For seven years this number has followed me around, has Intruded in my most private data, and has assaulted me from the pages of our most public journals. This number as- sumes a variety of disguises, being some- times a little larger and sometimes a little smaller than usual, but never changing so much as to be unrecogniz- able. The persistence with which this number plagues me is far more than a random accident. There is, to quote a famous senator, a design behind it, some pattern governing its appearances. Either there really is something unusual about the number or else I am suffering from delusions of persecution. I shall begin my case history by tell- ing you about some experiments that tested how accurately people can assign numbers to the magnitudes of various aspects of a stimulus. In the tradi- tional language of psychology these would be called experiments in absolute Th1s paper was first read as an Invited Address before the Eastern Psychological As- sociation In Philadelphia on April IS, 193.5. Preparation of the paper was supported by the Harvard Psycho-Acoustic Laboratory un- der Contract NSort-76 between Harvard Uni- versity and the Office of Naval Research, U. S. Navy (Project NR142-201, Report PNR-174). Reproduction for any purpose of the U. S. Government is permitted. judgment. Historical accident, how- ever, has decreed that they should have another name. We now call them ex- periments on the capacity of people to transmit information. Since these ex- periments would not have been done without the appearance of information theory on the psychological scene, and since the results are analyzed in terms of the concepts of information theory, I shall have to preface