Switching Attention Within Working Memory is Reflected in the P3a Component of the Human Event-Related Brain Potential.

Stefan Berti

doi:10.3389/fnhum.2015.00701

Abstract

The flexible access to information in working memory is crucial for adaptive behavior. It is assumed that this is realized by switching the focus of attention within working memory. Switching of attention is mirrored in the P3a component of the human event-related brain potential (ERP) and it has been argued that the processes reflected by the P3a are also relevant for selecting information within working memory. The aim of the present study was to further evaluate whether the P3a mirrors genuine switching of attention within working memory by applying an object switching task: Participants updated a memory list of four digits either by replacing one item with another digit or by processing the stored digit. ERPs were computed separately for two types of trials: (1) trials in which an object was repeated and (2) trials in which a switch to a new object was required in order to perform the task. Object-switch trials showed increased response times compared with repetition trials in both task conditions. In addition, switching costs were increased in the processing compared with the replacement condition. Pronounced P3a’s were obtained in switching trials but there were no difference between the two updating tasks (replacement or processing). These results were qualified by the finding that the magnitude of the visual location shift also affects the ERPs in the P3a time window. Taken together, the present pattern of results suggest that the P3a reflects an initial process of selecting information in working memory but not the memory updating itself.

Highlights

The human working memory system comprises of cognitive processes enabling the maintenance and access of relevant information in the service for mental tasks or action control
This question can be investigated by application of event-related brain potentials (ERPs) by testing whether components typically correlated with processes of attentional orientation in the sensory environment are associated with performance in working memory tasks
Switching trials are accompanied by an increased positive ERP component peaking around 300 ms at fronto-central electrodes

Summary

Introduction

The human working memory system comprises of cognitive processes enabling the maintenance and access of relevant information in the service for mental tasks or action control (for instance, see Cowan, 1998). The question arises whether these two functions—selection of relevant information in the sensory environment and selection of relevant information in working memory–share some neuro-cognitive processes (for instance, see Awh and Jonides, 2001; Bledowski et al, 2010). This question can be investigated by application of event-related brain potentials (ERPs) by testing whether components typically correlated with processes of attentional orientation in the sensory environment are associated with performance in working memory tasks (for instance, see Griffin and Nobre, 2003; Berti, 2008; Kuo et al, 2009). The association between the P3a component (as an index of attentional allocation to sensory information) and switching within working memory is tested

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