Attentional Requirements of Automatic and Controlled Processing

The attentional demands of automatic and controlled processing were investigated in a dual task paradigm. Subjects performed consistent and varied mapping versions of a Sternberg memory search task, both separately and together with a recognition running-memory task. In different conditions, subjects were instructed to maximize their performance on either the Sternberg or running memory tasks or to emphasize the tasks equally. Processing priority and memory load had large effects on performance when the variably mapped version of the Sternberg task was paired with the running memory task. Performance decrements in these conditions were accompanied by trade-offs in the amplitude of the P300 component of the event-related brain potential, presumably reflecting the distribution of attention between the tasks. Performance in the consistently mapped version of the Sternberg task was relatively unaffected by memory load or dual task demands. Large P300s, which were insensitive to manipulations of memory load and priority, were elicited in the consistently mapped conditions. These P300s appear to reflect the obligatory allocation of attention to task-relevant events during automatic processing.