Stimulus-driven selection precedes and dominates top-down attentional control: Behavioral and electrophysiological evidence.

Selection of behaviorally relevant visual information relies on interactions between stimulus-driven and top-down controlled attention, yet their concurrent cortical dynamics remain poorly understood. Using EEG and a feature-based attentional shifting paradigm, we tracked early sensory processing of frequency-tagged flickering stimuli and behavior while participants simultaneously selected a cue-matching color (stimulus-driven selection) and a learned associate color (top-down selection). Steady-State Visual Evoked Potentials (SSVEPs) showed an initial amplitude enhancement of the stimulus-cued color at the expense of the top-down matched and unattended colors, which was mirrored in behavioral costs. From ∼500 ms after cue onset onwards, SSVEP amplitudes for the top-down selected color increased while stimulus-driven amplitudes decreased towards comparable levels and suppression of the uncued color persisted. Cross-correlation analyses of SSVEP amplitude and behavioral response time courses revealed closely matching attentional selection profiles. Together, these findings are consistent with a sequential attentional cascade in which early stimulus-driven selection predominates and is only later resolved by top-down guided stimulus selection that redistributes attentional resources between both to-be-attended colors.