Hermann Grid Illusion

The Hermann Grid Illusion is a visual effect where gray spots appear at the intersections of black squares on a white grid, but these spots seem to disappear when you look directly at them. This occurs because our visual system processes contrast and brightness differently in peripheral vision versus direct focus. The brain's interpretation of contrast at the intersections causes these illusions of faint spots, which aren't actually present in the image. Essentially, it's a trick of how our eyes and brain work together to interpret contrasting patterns, highlighting the complex ways we perceive visual information.