Visual attention allows us to focus on important visual stimuli. The brain cannot process all visual information at once, so it relies on mechanisms like pre-attentive perception, focus, saccades, and fixations to select what to attend to. Pre-attentive perception processes unconscious visual information. Focus provides high visual resolution only in the small fovea region where our eyes are directed. Saccades are rapid eye movements that allow us to see our surroundings sharply by focusing our fovea on different locations. Fixations maintain the eyes' gaze on a single location for a brief period. Tunnel vision can occur when cognitive load increases, narrowing the useful field of vision and causing peripheral details to be missed.