Phasic modulation of attentional rhythmic sampling according to task demands

Abstract

Attention is considered to periodically allocate cognitive resources to task-relevant stimuli, thereby sequentially sampling multiple stimuli in the temporal domain. However, whether the temporal dynamics of attentional sampling are modulated by the task at hand has yet to be fully elucidated. This study explores the dynamics of attentional sampling and the task modulation of these dynamics using high-frequency steady-state visual evoked potential (SSVEP). Participants were asked to select one of two visual stimuli or integrate both as a single target, with stimuli tagged at 42 Hz and 44 Hz. Analysis of SSVEP envelopes revealed the attention periodically samples at theta band (4-6 Hz) in both tasks. Notably, the phase relationship between the SSVEP envelopes differed between tasks, with distinct phases in the selection task and similar phases in the integration task. This phase modulation of the task was mediated by neural oscillations in the right frontoparietal areas. The phase difference between SSVEP envelopes correlated with behavioral performance in the integration task but not in the selection task. These results demonstrate a flexible and task-dependent mechanism for attentional rhythmic sampling, in which neural oscillations align stimuli processing according to task demands.