ABSTRACT
Structural and capacity theories of dual-task performance are contrasted and a hybrid conception of structure-specific capacity is proposed in which processing resources reservoirs are defined by processing structures. A review of the literature identifies candidates for structural resource reservoirs, defined by input and output modalities, stages of processing, and hemispheres of processing. An experiment is reported in which encoding and response modalities of a digit-processing task are varied, as it is time-shared with a tracking task, whose difficulty is manipulated. The results are interpreted in terms of the concepts of capacity, structure, and resource pools.
