Differential role of beta band activity in a dual-task working memory paradigm under internally vs. externally directed cognition.

Internally directed cognition (IDC), whether spontaneous or intentional, has been associated with impaired performance in cognitive tasks. Yet, the neurophysiological mechanisms underpinning this disruption remain poorly understood. In the present study, we characterized the neural correlates of IDC and identified how they impact on performance in a color-recall working memory task using electroencephalography (EEG). Participants performed a novel dual-task paradigm involving either self-referential (IDC) or perceptual processing of adjectives, involving externally directed cognition (EDC) followed by a color-recall task. IDC enhanced late frontal positivity in EEG over medial-frontal electrodes as a marker of sustained self-referential processing. Time-frequency analyses further revealed increased event-related desynchronization in alpha and beta bands during stimulus encoding in the IDC condition, as well as increased alpha synchronization during the delay period, consistent with internal attention maintenance. To capture trial-level variability in task performance, we applied conditional quantile regression to individual trial-level observations. Results showed that beta desynchronization in interaction with condition type during encoding influenced performance significantly in trials with low errors, whereas trials with high error in color recall were better explained by increased reaction times. These findings provide converging electrophysiological evidence for distinct neural signatures of internally directed cognition and highlight their behavioral consequences in working memory performance.