The relationship between working memory and distractor processing in visual selective attention

Abstract

Selective attention is the ability to attend to relevant information, while disregarding irrelevant information. Neural signatures of selective attention include event-related lateralisations of both the negative (N2pc) and the positive (Ptc) voltage, which are suggested to reflect visual target enhancement and distractor suppression, respectively. Our prior research found that more salient visual items elicited an earlier and stronger Ptc with improved performance, while the opposite was true for less salient items. Additionally, high working memory capacity (HWMC) participants performed better with a tentatively stronger Ptc than low working memory capacity (LWMC) participants. We followed up our preliminary results with two experiments that further investigated these lateralised components and cognitive capacity. Experiment 1 investigated whether a modified localised attentional interference (LAI) task would show WMC differences. A ‘memory probe’ required observers to recall a certain element in the task after a set number of trials. Individuals who performed better on the memory probe performed better on the LAI task. We also found that the LWMC group exhibited a compensatory process, which showed that while they distinguished between the distractors more, they performed worse on the memory probe than the higher WMC groups. Experiment 2 investigated whether a more salient distractor would elicit a stronger Ptc signal and draw stronger neural differences in WMC. We found that the Ptc amplitude was the same and overall small for both distractor conditions, suggesting that suppression may not have been needed due to the greater physical differences between the distractors. We also found that HWMC participants elicited a late N2pc, postulated as higher cognitive functioning. All things considered, our studies suggest that the Ptc does not necessarily reflect stronger suppression, and that other qualities may reveal finer details of one’s cognitive capacity.