The Magical Number Seven, Plus ot Minus Two

2006-03-29T06:58:59Z

The Magical Number Seven, Plus ot Minus Two: Some Limits on Our Capacity for Processing Information
by George A. Miller

There is a clear and definite limit to the accuracy with which we can identify absolutely the magnitude of a unidimensional stimulus variable. I would propose to call this limit the span of absolute judgment, and I maintain that for unidimensional judgments this span is usually somewhere in the neighborhood of seven. We are not completely at the mercy of this limited span, however, because we have a variety of techniques for getting around it and increasing the accuracy of our judgments. The three most important of these devices are (a) to make relative rather than absolute judgments; or, if that is not possible, (b) to increase the number of dimensions along which the stimuli can differ; or © to arrange the task in such a way that we make a sequence of several absolute judgments in a row.

I suspect that there is also a span of perceptual dimensionality and that this span is somewhere in the neighborhood of ten, but I must add at once that there is no objective evidence to support this suspicion.

...there is a finite span of immediate memory and that for a lot of different kinds of test materials this span is about seven items in length. Absolute judgment is limited by the amount of information. Immediate memory is limited by the number of items. In order to capture this distinction in somewhat picturesque terms, I have fallen into the custom of distinguishing between bits of information and chunks of information. The span of immediate memory seems to be almost independent of the number of bits per chunk, at least over the range that has been examined to date. The contrast of the terms bit and chunk also serves to highlight the fact that we are not very definite about what constitutes a chunk of information.

Zero Brane

The Magical Number Seven, Plus ot Minus Two