Working Memory

Working memory (or short-term memory) is information temporarily held accessible in the mind. It is used in the completion of mental tasks such as comprehending language, following instructions, and solving mathematical problems. Many working memory measures correlate with intelligence rather strongly, and the average capacity of working memory increases with age in childhood. An adult can concurrently hold in mind about 4 separate, simple items, or often about 7 items by using mnemonic strategies (such as remembering a telephone number by silently rehearsing it and breaking it in to groups of 3 or 4 digits). Working memory is important for educational psychology in at least two ways. First, knowledge of the demands of a task on working memory helps in predicting the task difficulty. Second, knowledge of individual differences in working memory capability helps in understanding why scholastic performance varies.

Working memory differs from the vast information that one has learned over a lifetime, or long-term memory. To illustrate, suppose one knows the sentence The quick brown fox jumped over the lazy dog. If, on Tuesday, one recalls only that the sentence began, “The quick brown fox” whereas on Wednesday, one recalls only that the sentence ended, “jumped over the lazy dog,” it is impossible to recover the message.

However, if one is able to restore the central concepts from both parts of the sentence into working memory at once, one can imagine the fox jumping over the dog. If a story problem includes too many ideas at once, the listener or reader may find it impossible to integrate them in working memory. Similarly, it would be unwise to ask a preschool child to “put the small paint brush on the middle shelf, put the large brush along with the paint on the top shelf, and move everything that was already on the middle shelf down to the bottom.” One must break up this request into smaller parts to be carried out separately.

There appear to be multiple working memory mechanisms. A very small but important set of ideas can be in the focus of one's attention and awareness at once. However, working memory goes beyond what is in focus. There also are mechanisms to hold more information just beyond awareness. This may include mental representations of the progression of speech sounds in a sentence that one heard seconds ago, or the spatial arrangement of players in a basketball game one is watching. Psychologists posit temporary holding areas for such information, termed buffers, with different buffers for different types of information. Some researchers, such as Nelson Cowan, think of the buffers collectively as temporarily activated portions of long-term memory. Each type of mental representation may slip out of the focus of attention momentarily, but it might be recovered from the buffer. Thus, individuals may not be able to concentrate simultaneously on all [Page 1016]parts of a sentence they have just heard, but they might be able to repeat it by shifting their focus from one part of the sentence to the next while making use of information persisting for several seconds in a phonological buffer.

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