Competitive tradeoffs between working memory and attention: An fMRI approach

Abstract

Previous research has highlighted a close relationship between working memory (WM; i.e., the short-term maintenance and manipulation of internal information) and attention (i.e., the selective processing of a limited amount of external information). This reciprocity between WM and attention can be thought of as two sides of the same coin, such that WM (internal) and visual attention (external) could draw from, and thus compete for, a common cognitive resource. To examine the behavioral and neural characteristics of this interaction, we acquired fMRI data during a dual-task paradigm that simultaneously and systematically taxed both internal (WM) and external (visual) attentional load. Participants remembered one or two images (i.e., low vs. high internal load) for a delayed match-to-sample task. During the delay, participants performed a series of visual searches for target items that were either highly distinct from or similar to visual distractors (i.e., low vs. high external load). Behavioral data revealed that the impact of internal load on memory performance was inversely related to the impact of external load on search performance, suggesting that the effective processing of cognitive load in one domain increased susceptibility to load in the other domain. For example, for participants whose search performance was less affected by high external load, memory performance was more impaired by high internal load. Neural activity also revealed robust interactions between the two domains, such that parietal and temporal regions were differentially recruited to manage internal load in the face of low and high external load, respectively. Moreover, individual differences in independent measures of visual WM capacity and visual search efficiency modulated these behavioral and neural tradeoffs between internal and external attention. Collectively, these findings support the idea of WM and visual attention as competitive and interdependent constructs, whose interactions are processed by a network of fronto-temporo-parietal substrates. Meeting abstract presented at VSS 2015