Visual and auditory working memory capacity.

activated portion of the information in permanent memory, which extends beyond the focus of attention to include some automatically activated information (see Fig. 1). When researchers use the term 'working memory', some of them seem to be referring only to the focus of attention, whereas others seem to be referring to all of the temporarily activated information. It is also likely that certain inactive portions of memory can be stored in a way that allows them to be recalled (or reactivated) quickly 2,6,7. For example, in a reasoning problem involving rainbow colors, encoding the seven colors of the rainbow as the name 'Roy G. Biv' and keeping that name in mind makes the color names easily accessible while using up perhaps only one to three items of working memory capacity. There have been some attempts to go beyond the observed working memory limits to glean the limits of the underlying processing components. Broadbent 8 suggested, on the basis of past evidence, that the true capacity limit is about three items (presumably when the contributions of mnemonically useful processes such as rehearsal and long-term memorization have been eliminated). For example, this is about the number of items that can be recalled without error across many trials, and about the maximum number of items that can be grouped together into a single 'chunk', although the actual limit may be closer to four. Other researchers have proposed similar capacity limits of three or four items in the number of processing channels for visual search 9 , the number of items that can be enumerated quickly, without a slow, serial counting process 10 , and the number of moving visual items that can be tracked at the same time 10,11. A similar limit of about four items has been found when subjects encounter a spatial array of printed characters 12 or a spatiotemporal array of spoken characters 13 and must report them all. It is not clear if all of these similar limits are related; if so, perhaps they reflect the capacity limit of the focus of attention 6. Recently, Luck and Vogel 14 have contributed to this area in an important way. They first presented a spatial array of colored squares or rectangles on every trial. The second presentation was another array that could differ from the first array in the color of one item. Subjects were able to carry out the task …