Working memory is measured by separate storage-based and manipulation-based cognitive tasks.

Evidence

2.2.3 Cognitive Tasks Letter-Number Sequencing (LNS) The LNS (Wechsler 1997 ) measures mainly the storage component of WM although some manipulation is required. Participants heard a combination of numbers and letters and were asked to recall the numbers in ascending order, then the letters in alphabetical order. The number of items per trial increased by one every three trials; the task stopped when all three trials of a given length were repeated incorrectly. The outcome measure was the number of correct trials. Reading Span Task (RST) The RST places greater emphasis on manipulation (Daneman and Carpenter 1980 ). In each trial participants read aloud unconnected complex sentences of variable length and recalled the final word of each sentence at the end of a trial. The number of sentences per trial increased by one every five trials, from two to five sentences. All participants started with trials of two sentences and completed all 25 trials. The outcome measure was the overall number of correctly recalled words. — Dijk, Pim van, Physiology, Psychoacoustics and…, 1251

Categorization

• DEFINE: Distinguishes LNS (storage-dominant WM) from RST (manipulation-dominant WM), giving the reader a clear operational contrast between two standard test instruments.