Not passive sponges: When attention wanes, our brains are less synchronized with the environment

Without even being aware, humans are amazingly sensitive to the structures around them. Is this sensitivity constant or does it fluctuate along with our attentional states? To answer this foundational question, we deployed temporally sensitive measures that allow us to track neural entrainment—the synchronization of brain activity to environmental regularities—alongside fluctuations in attentional states. Participants (n = 78) viewed both random and structured visual streams while performing a task to index fluctuating attentional states. Structured streams evoked robust neural entrainment and reduced attentional lapses. Moreover, attentional states varied with neural entrainment. Across participants, those who displayed greater neural entrainment had reduced attentional lapses. And critically, even within individuals, greater entrainment was observed during periods of greater attentional focus. Our sensitivity to structure and attentional states are therefore inextricably linked: structures stabilize our attentional states and our sensitivity to structure dynamically mirrors the ebb and flow of human attention.