Magical Number Seven: Information Processing Then and Now.

摘要

The article was published the following year in the Psychological Review. Both the spoken version and the written version (here referred to as 7 + or - 2) were immediate successes. A survey conducted twenty years later found that 7 + or - 2 was the single most often cited paper in cognitive psychology (Garfield, 1975). Every student of cognitive psychology has been exposed to it, and many cognitive psychologists, including myself, have been profoundly influenced by it. The central thesis of 7 + or - 2 is that the number 7 occurs in two contexts. The first context is absolute judgements of brightness, loudness, pitch, extent, and so on. In absolute judgements - that is, classification of sensory stimuli into categories - 7 + or - 2 is the effective number of categories that the subject can maintain. This number is derived from what was then a novel statistical computation: the 2 to 3 bits of information transmitted by an observer in these tasks. To transmit more than 3 bits of information in an absolute judgement, a subject requires sensory stimuli that vary in more than one dimension. The transmitted information in each component dimension suffers somewhat as new dimensions are added; nevertheless, subjects can transmit enormously greater amounts of information about multidimensional stimuli than about one-dimensional stimuli. (sdw)