Phasic modulation of attentional rhythmic sampling according to task demands

Attention is thought to periodically allocate cognitive resources to task-relevant stimuli, enabling the sequential sampling of multiple stimuli over time. However, whether the specific task influences the temporal dynamics of attentional sampling remains not fully understood.

This study investigates the dynamics of attentional sampling and how these dynamics are influenced by task demands, using high-frequency steady-state visual evoked potentials (SSVEPs). Participants were instructed to either select one of two visual stimuli or integrate both stimuli into a single target, with the stimuli tagged at 42 Hz and 44 Hz, respectively. Analysis of the SSVEP envelopes revealed that attention periodically samples stimuli within the theta band (4-6 Hz) in both tasks. Notably, the phase relationship between the SSVEP envelopes differed across tasks: distinct phases were observed in the selection task, whereas similar phases were found in the integration task. This task-dependent phase modulation was mediated by theta-band neural oscillations in the brain. Furthermore, the phase difference between SSVEP envelopes correlated with behavioral performance in the integration task but not in the selection task.

These findings demonstrate a flexible, task-dependent mechanism for rhythmic attentional sampling, wherein neural oscillations align stimulus processing according to the specific demands of the task.