Further evidence relating mental capacity, short-term storage space, and operational efficiency

According to R. Case, a subject's Total Processing Space is the sum of his Short-term Storage Space (STSS) and Operating Space (OS). Case has hypothesized a trade-off between the two, that is, an increase in operational efficiency leads to a decrease in Operating Space and consequently more Short-term Storage Space is available for information processing. To test this hypothesis 137 high school students were tested to estimate operational efficiency (assigned a time limit to finish the Figural Intersection Test), Pascual-Leone's Structural M-capacity, Ms (i.e., STSS in Case's model), and Functional M-capacity, Mf. Besides other results a significant positive correlation of .37 was obtained between operational efficiency and Ms/STSS, which suggests that subjects find it difficult to distribute attentional load from one reserve (OS) to another (STSS).