You become better at detecting broad, low-detail (“coarse”) features — like shapes, movements, or sudden changes in the environment. This comes from increased activity in subcortical visual pathways (like the superior colliculus and amygdala) that specialize in quick, rough visual analysis. You become less focused on fine details (like facial features or small text), but more able to spot threat-relevant cues (like movement in your periphery, or something large approaching you).