When you're anticipating to see something important, your brain doesn't just sit idle—it actively reshapes how it processes visual information across your entire field of view in accordance with your anticipations, and this comes with real costs.

We've known for decades from behavioral studies that attention involves behavioral tradeoffs: focusing on one location improves what you see there but impairs perception elsewhere. But how does the brain implement these benefits and costs before a target even appears?

To answer this, we designed a neuroimaging experiment that combined brain imaging with a visual discrimination task. Critically, we included a condition where participants were instructed to monitor multiple locations simultaneously (distributed attention), which allowed us to measure the visual cortex responses at where participants attended and unattended compared to attending ‘everywhere’. When people focused on a single location, their performance more than doubled compared to distributed attention. But performance at unattended locations didn't just stay neutral—it dropped to barely above chance.

Visual cortex activity strongly reflected these behavioral changes: neural responses increased at the attended location and actively decreased at unattended locations, mirroring the behavioral pattern. This suppression became stronger in higher-level visual areas. Even more striking, these changes were happening during the anticipation period—your brain was already reconfiguring before anything appeared on the screen.

This finding reveals that our attentional capacity cannot "turn up the volume" everywhere. Focusing somewhere means actively withdrawing neural resources from everywhere else, with measurable consequences for what you can perceive. This has important implications for designing systems—from cockpit displays to video games—that need to work with the fundamental limits of human attention.