Separating limits on preparation versus online processing in multitasking paradigms: Evidence for resource models.

We conducted 2 multitasking experiments to examine the finding that first-task reaction times (RTs) are slower in the psychological refractory period (PRP) paradigm than in the prioritized processing (PP) paradigm. To see whether this difference between the 2 paradigms could be explained entirely by differences in first-task preparation, which would be consistent with the standard response selection bottleneck (RSB) model for multitasking interference, we compared the size of this difference for trials in which a second-task stimulus actually occurred against the size of the difference for trials without any second-task stimulus. The slowing of first-task RTs in the PRP paradigm relative to the PP paradigm was larger when the second-task stimulus appeared than when it did not, indicating that the difference cannot be explained entirely by between-paradigm differences in first-task preparation. Instead, the results suggest that the slowing of first-task RTs in the PRP paradigm relative to the PP paradigm is partly because of differences between paradigms in the online reallocation of processing capacity to tasks. Thus, the present results provide new evidence supporting resource models over the RSB model. (PsycINFO Database Record