An examination of the relationship between selective attention and memory processes using event-related potentials (ERPs) and dual-task paradigms

The relationship between selective attention and memory operations were investigated with event-related potential (ERP) methodology and the dual task paradigm. Two experiments are presented that examine the early and late attention waveforms as well as the P300 component. In Experiment 1 sixteen participants performed dichotic listening alone and in conjunction with the varied-set (short-term memory) (STM) and fixed-set (long-term memory) (LTM) versions of Sternberg's memory scanning paradigm. ERP data were collected concurrently from both the auditory and visual tasks. The results showed that the STM task, but not the LTM task, reduced the amplitude of the auditory late Negative Difference (Nd). The auditory early Nd component was unaffected by either task. Furthermore, both the auditory and visual P300s were decreased in amplitude by all the dual-task conditions. These data suggest that the auditory late Nd is linked to more specific working memory processes than is P300.;In Experiment 2, twenty participants performed dichotic listening alone and in conjunction with memory scanning set sizes of 2, 4, and 6 digits. The results showed that the late Nd amplitude was reduced by the introduction of the scanning task, but there was no further workload effect. In contrast to the first study, there was a reduction in early Nd, but only at a memory-set size of 6 digits. Furthermore, both the auditory and visual P300s showed reductions in their amplitudes when a second task was introduced, but only the visual P300 showed sensitivity to the increase in memory-set size. The results suggest that: (1) although the auditory late Nd reflects working memory operations, it is not linked to the memory scanning process, (2) late Nd and P300 reflect different working memory processes operating in parallel, and (3) stimulus modality appears to be an important determinant of P300 amplitude. The results of both experiments as well as additional mismatch negativity (MMN) and the N100-P200 ERP complex data are discussed within the framework of two models of information processing. An explanation of the relationship between selective attention and working memory is offered.