Short-term memory

Retention over a brief interval. Immediate span is one assay, not a complete measure of all representations that can influence immediate behavior.

Chunking groups separate items into meaningful units for recognizing patterns or using short-term memory. Several digits can be treated as one familiar date, for example, so the same number of visible symbols can require different numbers of remembered units. The grouping draws on knowledge in long-term memory; inserting spaces alone does not make an unfamiliar pattern meaningful.

William G. Chase and Herbert A. Simon investigated these units by asking three chess players of differing skill to reconstruct positions and examining pauses and successive glances during reconstruction. The pattern of pieces placed together provided evidence about the structures a player perceived, rather than simply measuring the total number of pieces remembered.^[ref] Expertise can therefore improve performance by changing the representation of the material, without demonstrating an equal improvement in every unrelated short-term memory task.

Temporary retention of verbal material. Auditory presentation, phonological coding, rehearsal and output requirements can contribute differently to a measured span.

A task measuring the sequence length of digits that can be reproduced under specified conditions. Forward repetition and backward manipulation are different demands; modality and presentation rate also matter.