"The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information" is a 1956 paper by the cognitive psychologist George A. Miller. In it Miller showe a number of remarkable coincidences between the channel capacity of a number of human cognitive and perceptual tasks. In each case, the effective channel capacity is equivalent to between 5 and 9 equally-weighted error-less choices: on average, about 2.5 bits of information. Miller did not draw any firm conclusions, simply hypothesizing that the recurring sevens might represent something deep and profound or be just a pernicious, Pythagorean coincidence.