A methodological assessment and evaluation of dual-task paradigms

This article outlines three major assumptions often implicitly made in dual-task experiments conducted to assess attentional capacity requirements of memorial processes. These assumptions are shown to be incorrect. Three criteria which should be met in dual-task experiments that draw inferences from secondary task decrements are proposed: (1) there should be resource trade-off with the secondary task sensitive to the resource demands of the primary task; (2) there should be equivalence of single and dual primary task performance; and (3) the secondary task must remain resource sensitive throughout the experiment. An experiment was carried out in which the primary and secondary tasks were designed according to these criteria. The results demonstrate that when the criteria are met then secondary task performance can be predictive of primary task difficulty: however, the experiment also highlights the fact that a simple assessment of capacity will not predict total task performance.