Hermann grid

The Hermann grid is a visual illusion where a grid of black squares separated by white lines appears to have gray spots at the intersections of the white lines, which seem to disappear when you focus directly on each intersection. This occurs due to the way our eyes and brain process contrast and brightness. The cells around the intersections cause our eyes to be less sensitive to the white areas, creating the illusion of dimmed spots. The Hermann grid helps illustrate how our visual system processes light and dark contrasts, highlighting the way our perception can be influenced by surrounding areas.